Acute Retensi Pd Lelaki Dan Kematian
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Mortality in men admitted to hospital with acute
urinary retention: database analysis
James N Armitage, Nokuthaba Sibanda, Paul J Cathcart, Mark Emberton and
Jan H P van der Meulen
BMJ published online 8 Nov 2007;
doi:10.1136/bmj.39377.617269.55
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RESEARCH
Mortality in men admitted to hospital with acute urinary
retention: database analysis
James N Armitage, urology research fellow,1 Nokuthaba Sibanda, research fellow,2 Paul J Cathcart, urology
registrar,1 Mark Emberton, reader in interventional oncology,3 Jan H P van der Meulen, reader in public health
medicine and clinical epidemiology2
1
Clinical Effectiveness Unit, Royal
College of Surgeons of England,
London WC2A 3PE
2
Health Services Research Unit,
London School of Hygiene and
Tropical Medicine, London
3
Division of Surgery and
Interventional Science,
University College Hospital,
London
Correspondence to:
J H P van der Meulen
[email protected]
doi:10.1136/bmj.39377.617269.55
ABSTRACT
Objectives To investigate mortality in men admitted to
hospital with acute urinary retention and to report on the
effects of comorbidity on mortality.
Design Analysis of the hospital episode statistics
database linked to the mortality database of the Office for
National Statistics.
Setting NHS hospital trusts in England, 1998-2005.
Participants All men aged over 45 who were admitted to
NHS hospitals in England with a first episode of acute
urinary retention.
Main outcome measures Mortality in the first year after
acute urinary retention and standardised mortality ratio
against the general population.
Results During the study period, 176 046 men aged over
45 were admitted to hospital with a first episode of acute
urinary retention. In 100 067 men with spontaneous
acute urinary retention, the one year mortality was 4.1%
in men aged 45-54 and 32.8% in those aged 85 and over.
In 75 979 men with precipitated acute urinary retention,
mortality was 9.5% and 45.4%, respectively. In men with
spontaneous acute urinary retention aged 75-84, the
most prevalent age group, the one year mortality was
12.5% in men without comorbidity and 28.8% in men with
comorbidity. The corresponding figures for men with
precipitated acute urinary retention were 18.1% and
40.5%. Compared with the general population, the
highest relative increase in mortality was in men aged
45-54 (standardised mortality ratio 10.0 for spontaneous
and 23.6 for precipitated acute urinary retention) and the
lowest for men 85 and over (1.7 and 2.4, respectively).
Conclusions Mortality in men admitted to hospital with
acute urinary retention is high and increases strongly with
age and comorbidity. Patients might benefit from
multi-disciplinary care to identify and treat comorbid
conditions.
INTRODUCTION
Acute urinary retention is a severe complication of
benign prostatic hyperplasia. With an ageing population, it represents a major public health issue in the
western world. The reported incidence of acute urinary
retention in large population based studies varies from
2.2 to 6.8 per 1000 men per year.1-4 As many as one in
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10 men in their 70s may experience acute urinary
retention within five years.1 It is a urological emergency that requires immediate treatment with a urinary
catheter. After the acute period, most men will be
offered a trial without catheter and about 60% will
resume spontaneous voiding.5 In the United Kingdom,
about one in five will undergo further surgical
treatment in the next six months, but about 15% will
experience a recurrence within the same time period.3
Although acute urinary retention is a direct
manifestation of progression of benign prostatic
hyperplasia, several studies have also found
associations with major morbidities.3 6-8 Occurring
either spontaneously or after a precipitating event, it
may therefore be a “harbinger” of severe systemic
disease. We studied to what extent the occurrence of
acute urinary retention among men admitted to
hospital confers an increased risk of death compared
with men in the general population of similar age.
METHODS
Data
We extracted data from the hospital episode statistics
(HES) database, an administrative database of all
admissions to NHS hospitals in England. A unique
patient identifier allowed us to link records of different
hospital admissions in the same patient. Each record
contains diagnostic fields coded according to ICD-10
(international classification of diseases, 10th revision)
and operative procedure fields coded according to the
UK Tabular List of the Classification of Surgical Operations
and Procedures.9 For all admissions after 1 April 1998,
the HES database was linked to the mortality database
of the Office for National Statistics.10 11 In 2.4% of men
who were reported as having died after acute urinary
retention, we found a record of a subsequent hospital
admission. For these contradictory results, we
considered the information on death to be incorrect
and therefore analysed these men as being alive until
the end of the study period.
Definitions
A patient was considered to have had primary acute
urinary retention (acute urinary retention for the first
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time) if there was no record in the HES database of a
previous admission for this condition in at least the
preceding six months. We chose a period of six months
because about 80% of men who experience recurrence
do so within this time period.4
We defined acute urinary retention (R33) as
spontaneous if it was recorded in the first diagnostic
field or if benign prostatic hyperplasia (N40) was the
primary diagnosis and acute urinary retention was
recorded in another diagnostic field. In all other cases
we considered it to be precipitated.4 5 12
Inclusion criteria
To identify admissions of men aged over 45 who had
primary acute urinary retention, we followed a stepwise process. Firstly, we selected the records of all
229 089 men who were admitted at least once with an
ICD-10 code indicating acute urinary retention (R33)
in any of the first seven diagnostic fields from 1 April
1998 to 31 March 2005. Secondly, we sequentially
deleted the records of 29 924 patients with codes for
prostate cancer (ICD-10 code C61), 1150 patients
with codes for multiple sclerosis (G35), and 6380
patients with codes for Parkinson’s disease (G20) in
any diagnostic field of any record. Thirdly, we
excluded the records of 15 592 men who were
admitted for acute urinary retention in the period
from 1 April 1998 to 30 September 1998 to include
only men with primary acute urinary retention.
Identification of comorbidity
We used an adaptation of the Charlson score designed
for use with administrative data.13 14 This score was
validated in HES data for patients undergoing
urological cancer surgery in England.15 Comorbid
disease was defined as present if it appeared in the
records of the index admission (the admission for
primary acute urinary retention) or of admissions that
occurred in the six months before the index admission.
Statistical analysis
We used the Kaplan-Meier method to estimate age
specific mortality within 90 days and one year after
primary acute urinary retention. To compare mortality
within the first year with that of men in the general
population, we calculated standardised mortality ratios
according to age and comorbidity. Standard rates were
mortalities specific for age group and calendar year for
men in the general population of England for
1999-2005. The standardised rates were calculated by
dividing the mid-year estimate of the number of men
within an age group alive in England and Wales by the
number that died during that year. The confidence
intervals for the standardised mortality ratios were
obtained using Byar’s approximation.16
RESULTS
From 1 October 1998 to 31 March 2005, 176 046 men
were admitted to NHS hospitals with a diagnosis of
primary acute urinary retention (table 1). Of these
men, 100 067 (56.8%) had spontaneous acute urinary
retention (mean age 73.5 (SD 10.5) years) and 75 979
(43.2%) had precipitated retention (mean age 74.5 (SD
10.9) years). In all age groups, mortality was higher in
men with precipitated acute urinary retention.
Overall, 14.7% of men with spontaneous acute
urinary retention and 25.3% men with precipitated
acute urinary retention died within the first year
(table 1). About half of these deaths (54.9%) occurred
within the first 90 days.
In men with spontaneous acute urinary retention,
mortality at one year increased strongly with age,
from 4.1% in patients aged 45-54 to 32.8% in those
aged 85 and over (table 1). In men with precipitated
acute urinary retention, mortality at one year increased
Table 1 | Age specific mortality within 90 days and one year after spontaneous and precipitated primary acute urinary retention
and standardised mortality ratios (SMR) against the general population of England
Mortality
Age group
Total
admissions
90 days
1 year
Deaths
Rate (95% CI)
Deaths
Rate (95% CI)
SMR
(95% CI)
10.0 (8.8 to 11.5)
Spontaneous acute urinary retention
45-54
5 580
119
2.2 (1.8 to 2.6)
216
4.1 (3.6 to 4.6)
55-64
13 918
329
2.4 (2.2 to 2.7)
692
5.3 (4.9 to 5.7)
5.0 (4.6 to 5.4)
65-74
30 661
1 301
4.3 (4.1 to 4.5)
2 822
9.7 (9.4 to 10.1)
3.3 (3.2 to 3.4)
75-84
36 086
2 752
7.8 (7.5 to 8.0)
6 070
17.9 (17.4 to 18.3)
2.3 (2.2 to 2.3)
≥85
13 822
2 153
15.8 (15.2 to 16.4)
4 315
32.8 (32.0 to 33.7)
1.7 (1.6 to 1.7)
Total
100 067
6 654
6.7 (6.5 to 6.8)
14 115
14.7 (14.5 to 14.9)
2.2 (2.2 to 2.3)
Precipitated acute urinary retention
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45-54
4 979
276
5.6 (5.0 to 6.3)
453
9.5 (8.7 to 10.4)
23.6 (21.5 to 25.9)
55-64
8 736
625
7.2 (6.7 to 7.8)
1 043
12.5 (11.8 to 13.2)
12.0 (11.3 to 12.8)
65-74
20 461
2 095
10.3 (9.9 to 10.8)
3 492
17.8 (17.3 to 18.3)
6.1 (5.9 to 6.3)
75-84
28 148
4 551
16.4 (15.9 to 16.8)
7 711
28.7 (28.1 to 29.2)
3.7 (3.6 to 3.8)
≥85
13 655
3 792
28.0 (27.3 to 28.8)
5 983
45.4 (44.6 to 46.3)
2.4 (2.3 to 2.4)
Total
75 979
11 339
14.8 (14.6 to 15.1)
18 682
25.3 (24.9 to 26.3)
3.5 (3.5 to 3.6)
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to a similar extent in the corresponding age groups
from 9.5% to 45.4%.
Although the highest one year mortality was
observed in the oldest age groups, the age specific relative increase in mortality was highest in the youngest
age groups (table 1). In men aged 45-54 years, compared with the general population there was a 10-fold
increase in mortality in those with spontaneous acute
urinary retention and an almost 24-fold increase in
mortality in men with precipitated acute urinary retention. The corresponding increases in men aged 85 and
over were 1.7-fold and 2.4-fold, respectively.
More than a third of men with acute urinary retention had at least one major comorbid condition as
defined by the Charlson score (table 2). As expected,
comorbidity was more prevalent in men with precipitated rather than acute urinary retention (43.5% v
29.1%). The presence of comorbidity greatly increased
mortality. For example, in men with spontaneous acute
urinary retention aged 75-84 years, the most prevalent
age group, the presence of comorbidity more than
doubled the one year mortality, from 12.5% to
28.8%. In men with precipitated acute urinary retention in the corresponding age group, the presence of
comorbidity had a similar effect, and one year mortality increased from 18.1% to 40.5%.
One year mortality was high in men with comorbidity in the oldest age group (44.3% in spontaneous and
54.7% in precipitated acute urinary retention). The age
specific relative increase compared with the general
population, however, was again highest in the youngest age group (standardised mortality ratio 36.5 v 60.4,
respectively).
Even in men without comorbidity as defined by the
Charlson score, mortality within the first year after
acute urinary retention was considerably higher than
in the general population (table 2). For example, in
men with spontaneous acute urinary retention without
comorbidity, mortality was 4.4 times higher than in the
general population in the youngest age group and 1.4
times higher in the oldest age group. Similarly, in men
with precipitated acute urinary retention without
comorbidity, mortality was 8.4 times higher in the
youngest age group and 2.0 times higher in the oldest
age-group.
DISCUSSION
Mortality after primary acute urinary retention in men
admitted to hospital is high. Overall, we found that one
in seven men with spontaneous acute urinary retention
and one in four with precipitated acute urinary retention died in the first year. Mortality increased strongly
with age and the presence of comorbidity. Consequently, about half of the men aged 85 and over with
at least one comorbid condition died within the first
year after acute urinary retention. Although mortality
in men under 55 without comorbidity is not as high, it
was still at least four times higher than that observed in
men of similar age in the general population.
Methodological limitations
We included only men who were admitted to hospital
and did not consider those who were treated within
primary care or solely in a hospital emergency department. Those patients might have been in a better overall condition than the patients who were admitted.
According to a 2004 survey, however, only 10% of
UK urologists would not admit men presenting with
acute urinary retention.17 Also, a Dutch epidemiological study, the only population based study to date in
which the incidence of acute urinary retention was estimated through direct access to a prospectively collected primary care database, reported an incidence
of 2.2 per 1000 men per year.3 This is lower than the
incidence of 3.1 per 1000 men per year that we
reported previously based on hospital admissions in
England.4 We therefore consider it unlikely that we
missed a substantial number of men.
Table 2 | Age specific mortality within one year after spontaneous and precipitated primary acute urinary retention and
standardised mortality ratios (SMR) with and without comorbidity
Men with comorbidity (Charlson score ≥1)
Men without comorbidity (Charlson score 0)
Age
group
Total
admissions
1 year
Deaths
Rate (95% CI)
SMR (95% CI)
Total
admissions
1 year
Deaths
Rate % (95% CI)
SMR (95% CI)
Spontaneous acute urinary retention
45-54
4 590
77
1.8 (1.4 to 2.2)
4.4 (3.4 to 5.4)
990
139
14.7 (12.6 to 17.2)
36.5 (30.7 to 43.1)
55-64
10 987
232
2.3 (2.0 to 2.6)
2.1 (1.9 to 2.4)
2 931
460
16.7 (15.4 to 18.2)
15.8 (14.4 to 17.4)
65-74
21 981
1 099
5.3 (5.0 to 5.6)
1.8 (1.7 to 1.9)
8 680
1 723
21.0 (20.1 to 21.9)
7.1 (6.8 to 7.4)
75-84
24 155
2 843
12.5 (12.1 to 13.0)
1.6 (1.5 to 1.6)
11 931
3 227
28.8 (27.9 to 29.6)
3.7 (3.5 to 3.8)
≥85
9 268
2 400
27.3 (26.4 to 28.2)
1.4 (1.3 to 1.4)
4 554
1 915
44.3 (42.8 to 45.8)
2.3 (2.2 to 2.4)
Total
70 981
6 651
9.9 (9.7 to 10.2)
1.6 (1.5 to 1.6)
29 086
7 464
27.2 (26.7 to 27.7)
3.7 (3.6 to 3.8)
Precipitated acute urinary retention
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45-54
3 522
114
3.4 (2.9 to 4.1)
8.4 (6.9 to 10.1)
1 457
339
24.3 (22.1 to 26.6)
60.4 (54.2 to 67.2)
55-64
5 496
235
4.5 (4.0 to 5.1)
4.3 (3.8 to 4.9)
3 240
808
26.0 (24.5 to 27.6)
25.1 (23.4 to 26.9)
65-74
11 426
880
8.1 (7.6 to 8.6)
2.7 (2.6 to 2.9)
9 035
2 612
30.0 (29.1 to 31.0)
10.3 (9.9 to 10.7)
75-84
14 869
2 571
18.1 (17.5 to 18.8)
2.3 (2.2 to 2.4)
13 279
5 140
40.5 (39.6 to 41.3)
5.2 (5.1 to 5.4)
≥85
7 578
2 778
38.0 (36.9 to 39.2)
2.0 (1.9 to 2.0)
6 077
3 205
54.7 (53.4 to 55.9)
2.8 (2.7 to 2.9)
Total
42 891
6 578
16.1 (15.7 to 16.4)
2.3 (2.2 to 2.3)
33 088
12 104
38.1 (37.6 to 38.6)
5.0 (4.9 to 5.1)
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The Charlson score based on administrative data
underestimates the prevalence of comorbid
disease.18 19 Undetected comorbidity may account for
our observation that men without comorbidity
according to the Charlson score still had a higher
mortality than the general population. None the less,
we found that the Charlson score identified at least one
comorbid condition in more than a third of men with
acute urinary retention and that mortality was most
increased in this group. A more accurate instrument
could have shown an even more marked impact of
comorbidity.
The reported mortality after acute urinary retention
was based on the linkage between the HES database of
all admissions to NHS hospitals in England and the
mortality database of the Office for National Statistics.
Most (96%) patients had a date of death that was based
on robust linkage methods that relied on an exact
match of at least two of the NHS number (a unique
10 digit code allocated to an individual to enable
identification for NHS health care), date of birth, and
postcode. For these patients, we found contradictory
linkage results (that is, an admission date after a date
of death) in only 0.3% of patients. In the 4% of patients
remaining, we used a less robust linkage method
(partial match of date of birth and exact agreement of
sex and postcode) and found contradictory results in
54% of the patients. As explained before, we assumed
that men with contradictory mortality results were
alive until the end of the study period. Sensitivity
analyses of alternative assumptions showed that the
mortality for all men within one year after acute
urinary retention always changed by less than
0.5 percentage point, and in turn the relative increases
in mortality compared with the general population did
not change appreciably.
Comparison with other studies
We specifically looked at longer term mortality after
acute urinary retention. The only other study to date
that provides some evidence on mortality after acute
urinary retention was carried out in five healthcare
regions in the UK in the mid-1990s in 3966 men who
underwent prostatic surgery.20 That found that the
1242 men who underwent a prostatectomy after acute
urinary retention had a higher mortality in the first
90 days (3.0%) compared with the 2724 men who had
surgery for symptoms alone (0.7%). Other studies that
have reported on outcomes after acute urinary
retention tend to focus only on recurrence and the
need for prostatic surgery.4 12
Acute urinary retention shares several characteristics with fractured neck of femur. Both are acute and
serious age related events that almost always result in
hospital admission but do not directly cause death.
Two English studies have recently reported the one
year mortality in men after fractured neck of femur to
be just over 40%.21 22 Mortality clearly increased with
age from 20% in men aged 65-69 to 50% in men aged
85-89.21 Comorbidity was found to be an important
page 4 of 5
predictor of outcome, with mortality in the first year
about 1.5 times higher in patients with at least one
comorbid condition than in patients without
comorbidity.22
The comparison with fractured neck of femur shows
that acute urinary retention constitutes a health
problem of a similar magnitude. The overall one year
mortality was 20%, which is lower than that observed
after fractured neck of femur. The incidence of primary
acute urinary retention, however, is 3.1 per 1000 men
per year, which is higher than the incidence of
fractured neck of femur, estimated to be about 2.4 per
1000 men per year based on the HES database.
Explanations for the increased mortality
Though acute urinary retention is generally considered a urological emergency, serious consequences
are rare with appropriate treatment. Our finding of a
high mortality in the first year seems to contradict this.
An obvious explanation for the increased mortality is
that occurrence exposes men to risks associated with
admission to hospital, catheter related and other
nosocomial infections, and invasive procedures that
often need a general anaesthetic.
While these factors do play a role, the high mortality
seems to be linked mainly to comorbidity for several
reasons. Firstly, the presence of comorbidity according
to the Charlson score substantially increased mortality
within patients of similar age and with the same type of
acute urinary retention. Secondly, mortality was also
higher in patients with precipitated rather than
spontaneous retention. Precipitated retention occurs
after a triggering event that is unrelated to the prostate
and therefore a further indication of comorbidity.
Thirdly, there seems to be a “dose-response” relation
as the lowest mortality was found in patients with
spontaneous retention and no comorbidity according
to the Charlson score and the highest mortality in
patients with precipitated retention and comorbidity.
Lastly, a detailed inspection of the diagnostic fields in
patients with spontaneous acute urinary retention and
no comorbidity apparent showed that 58% of these
patients had at least one diagnosis not related to the
prostate and not captured by the Charlson score.
Of the patients who had comorbidity according to
the Charlson score, irrespective of the type of acute
urinary retention, about 30% had cardiovascular
disease, 25% diabetes, 25% chronic pulmonary
disease, and 15% a malignancy. The relatively high
prevalence of cardiovascular disease and diabetes is
consistent with the findings of recent aetiological
studies linking hypertension and metabolic syndrome
with the progression of benign prostatic hyperplasia.7 8
Clinical implications
The high mortality that we observed in men admitted to
hospital with acute urinary retention shows that they are
a vulnerable group of patients. These observations reinforce the importance to the clinician of adopting a multidisciplinary approach in the assessment and
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WHAT IS ALREADY KNOWN ON THIS TOPIC
The incidence of acute urinary retention strongly increases with age
Acute urinary retention seems to be associated with severe systemic disease
WHAT THIS STUDY ADDS
One in seven men admitted to hospital with spontaneous acute urinary retention and one in
four with precipitated acute urinary retention die within a year
Mortality is considerably higher in older men and in those with comorbidity
Patients with acute urinary retention are a vulnerable group and may benefit from urgent
multi-disciplinary care to identify and treat comorbid conditions
Funding: JNA was supported by the Bob Young Research Fellowship, the
Dunhill Medical Trust, and the Royal College of Surgeons of England research
fellowship scheme. JvdM received a national public health career scientist
award from the Department of Health and NHS research and development
programme.
Competing interests: None declared.
Ethical approval: Not required.
Provenance and peer review: Not commissioned; externally peer reviewed.
1
2
3
management of such patients.23 Men with acute urinary
retention should undergo a comprehensive investigation for comorbid disease. The extent to which mortality
after acute urinary retention can be reduced, however,
will depend on the nature and severity of the comorbidities involved and the effectiveness of the available treatments. For example, some patients will have
comorbidity that is already optimally treated and for
whom little further can be done.
Our observation that about half of the deaths after
acute urinary retention occur within the first 90 days
suggests that assessment of comorbidity must occur
promptly. Indeed, perhaps screening for other
morbidities should start in men presenting with lower
urinary tract symptoms attributable to benign prostatic
hyperplasia before they experience acute urinary
retention.
4
5
6
7
8
9
10
11
12
Research implications
The two most important unanswered questions relate
to the way in which comorbidities can be identified and
the extent to which their treatment will reduce mortality after acute urinary retention. In our view, research
building on administrative databases, such as the
hospital episode statistics, enriched through linkage
with additional clinical data seems to be the obvious
next step to answer both questions. Firstly, administrative databases can provide near complete follow-up in
terms of further treatment as well as death. Clinical
data, perhaps collected prospectively in a subgroup
of patients and linked to the administrative data at the
individual patient level, will allow a further exploration
of the impact of comorbidity according to its nature
and severity. The results of this will inform the
development of treatment strategies. Secondly, these
strategies can then be evaluated with research designs
that build on combining administrative data with data
derived from clinical trials.
We thank the Department of Health for providing the hospital episode statistics
data used in this study and Jim Lewsey, statistician at London School of Hygiene
and Tropical Medicine and the Royal College of Surgeons of England, for his
help with the extraction of the dataset.
13
14
15
16
17
18
19
20
21
22
23
Contributors: JNA, PJC, ME, and JHvdM designed the study; JNA and NS
conducted the statistical analyses; JNA and JHvdM drafted the paper; NS, PJC,
and ME commented on and contributed to the final version. JHvdM is guarantor.
BMJ | ONLINE FIRST | bmj.com
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Anderson R, et al. Urinary retention in patients with BPH treated with
finasteride or placebo over 4 years. Characterization of patients and
ultimate outcomes. The PLESS Study Group. Eur Urol
2000;37:528-36.
Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of
classifying prognostic comorbidity in longitudinal studies:
development and validation. J Chronic Dis 1987;40:373-83.
Romano PS, Roos LL, Jollis JG. Adapting a clinical comorbidity index
for use with ICD-9-CM administrative data: differing perspectives. J
Clin Epidemiol 1993;46:1075-9.
Nuttall M, van der Meulen J, Emberton M. Charlson scores based on
ICD-10 administrative data were valid in assessing comorbidity in
patients undergoing urological cancer surgery. J Clin Epidemiol
2006;59:265-73.
Breslow NE, Day NE. Statistical methods in cancer research.
Volume II. The design and analysis of cohort studies. IARC Sci Publ
1987;82:1-406.
Manikandan R, Srirangam SJ, O’Reilly PH, Collins GN. Management of
acute urinary retention secondary to benign prostatic hyperplasia in
the UK: a national survey. BJU Int 2004;93:84-8.
Romano PS, Roos LL, Jollis JG. Furthering evidence concerning the
use of a clinical comorbidity index with ICD-9-CM administrative
data. J Clin Epidemiol 1993;46:1085-90.
Schneeweiss S, Maclure M. Use of comorbidity scores for control of
confounding in studies using administrative databases. Int J
Epidemiol 2000;29:891-8.
Pickard R, Emberton M, Neal DE. The management of men with acute
urinary retention. BJU Int 1998;81:712-20.
Roberts SE, Goldacre MJ. Time trends and demography of mortality
after fractured neck of femur in an English population, 1968-98:
database study. BMJ 2003;327:771-5.
Roche JJW, Wenn RT, Sahota O, Moran CG. Effects of comorbidities
and postoperative complications on mortality after hip fracture in
elderly people: prospective observational cohort study. BMJ
2005;331:1374.
Kirby RS, Kirby M. The urologist as an advocate of men’s health: 10
suggested steps toward helping patients achieve better overall
health. Urology 2005;66:52-6.
Accepted: 7 October 2007
page 5 of 5
Mortality in men admitted to hospital with acute
urinary retention: database analysis
James N Armitage, Nokuthaba Sibanda, Paul J Cathcart, Mark Emberton and
Jan H P van der Meulen
BMJ published online 8 Nov 2007;
doi:10.1136/bmj.39377.617269.55
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RESEARCH
Mortality in men admitted to hospital with acute urinary
retention: database analysis
James N Armitage, urology research fellow,1 Nokuthaba Sibanda, research fellow,2 Paul J Cathcart, urology
registrar,1 Mark Emberton, reader in interventional oncology,3 Jan H P van der Meulen, reader in public health
medicine and clinical epidemiology2
1
Clinical Effectiveness Unit, Royal
College of Surgeons of England,
London WC2A 3PE
2
Health Services Research Unit,
London School of Hygiene and
Tropical Medicine, London
3
Division of Surgery and
Interventional Science,
University College Hospital,
London
Correspondence to:
J H P van der Meulen
[email protected]
doi:10.1136/bmj.39377.617269.55
ABSTRACT
Objectives To investigate mortality in men admitted to
hospital with acute urinary retention and to report on the
effects of comorbidity on mortality.
Design Analysis of the hospital episode statistics
database linked to the mortality database of the Office for
National Statistics.
Setting NHS hospital trusts in England, 1998-2005.
Participants All men aged over 45 who were admitted to
NHS hospitals in England with a first episode of acute
urinary retention.
Main outcome measures Mortality in the first year after
acute urinary retention and standardised mortality ratio
against the general population.
Results During the study period, 176 046 men aged over
45 were admitted to hospital with a first episode of acute
urinary retention. In 100 067 men with spontaneous
acute urinary retention, the one year mortality was 4.1%
in men aged 45-54 and 32.8% in those aged 85 and over.
In 75 979 men with precipitated acute urinary retention,
mortality was 9.5% and 45.4%, respectively. In men with
spontaneous acute urinary retention aged 75-84, the
most prevalent age group, the one year mortality was
12.5% in men without comorbidity and 28.8% in men with
comorbidity. The corresponding figures for men with
precipitated acute urinary retention were 18.1% and
40.5%. Compared with the general population, the
highest relative increase in mortality was in men aged
45-54 (standardised mortality ratio 10.0 for spontaneous
and 23.6 for precipitated acute urinary retention) and the
lowest for men 85 and over (1.7 and 2.4, respectively).
Conclusions Mortality in men admitted to hospital with
acute urinary retention is high and increases strongly with
age and comorbidity. Patients might benefit from
multi-disciplinary care to identify and treat comorbid
conditions.
INTRODUCTION
Acute urinary retention is a severe complication of
benign prostatic hyperplasia. With an ageing population, it represents a major public health issue in the
western world. The reported incidence of acute urinary
retention in large population based studies varies from
2.2 to 6.8 per 1000 men per year.1-4 As many as one in
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10 men in their 70s may experience acute urinary
retention within five years.1 It is a urological emergency that requires immediate treatment with a urinary
catheter. After the acute period, most men will be
offered a trial without catheter and about 60% will
resume spontaneous voiding.5 In the United Kingdom,
about one in five will undergo further surgical
treatment in the next six months, but about 15% will
experience a recurrence within the same time period.3
Although acute urinary retention is a direct
manifestation of progression of benign prostatic
hyperplasia, several studies have also found
associations with major morbidities.3 6-8 Occurring
either spontaneously or after a precipitating event, it
may therefore be a “harbinger” of severe systemic
disease. We studied to what extent the occurrence of
acute urinary retention among men admitted to
hospital confers an increased risk of death compared
with men in the general population of similar age.
METHODS
Data
We extracted data from the hospital episode statistics
(HES) database, an administrative database of all
admissions to NHS hospitals in England. A unique
patient identifier allowed us to link records of different
hospital admissions in the same patient. Each record
contains diagnostic fields coded according to ICD-10
(international classification of diseases, 10th revision)
and operative procedure fields coded according to the
UK Tabular List of the Classification of Surgical Operations
and Procedures.9 For all admissions after 1 April 1998,
the HES database was linked to the mortality database
of the Office for National Statistics.10 11 In 2.4% of men
who were reported as having died after acute urinary
retention, we found a record of a subsequent hospital
admission. For these contradictory results, we
considered the information on death to be incorrect
and therefore analysed these men as being alive until
the end of the study period.
Definitions
A patient was considered to have had primary acute
urinary retention (acute urinary retention for the first
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time) if there was no record in the HES database of a
previous admission for this condition in at least the
preceding six months. We chose a period of six months
because about 80% of men who experience recurrence
do so within this time period.4
We defined acute urinary retention (R33) as
spontaneous if it was recorded in the first diagnostic
field or if benign prostatic hyperplasia (N40) was the
primary diagnosis and acute urinary retention was
recorded in another diagnostic field. In all other cases
we considered it to be precipitated.4 5 12
Inclusion criteria
To identify admissions of men aged over 45 who had
primary acute urinary retention, we followed a stepwise process. Firstly, we selected the records of all
229 089 men who were admitted at least once with an
ICD-10 code indicating acute urinary retention (R33)
in any of the first seven diagnostic fields from 1 April
1998 to 31 March 2005. Secondly, we sequentially
deleted the records of 29 924 patients with codes for
prostate cancer (ICD-10 code C61), 1150 patients
with codes for multiple sclerosis (G35), and 6380
patients with codes for Parkinson’s disease (G20) in
any diagnostic field of any record. Thirdly, we
excluded the records of 15 592 men who were
admitted for acute urinary retention in the period
from 1 April 1998 to 30 September 1998 to include
only men with primary acute urinary retention.
Identification of comorbidity
We used an adaptation of the Charlson score designed
for use with administrative data.13 14 This score was
validated in HES data for patients undergoing
urological cancer surgery in England.15 Comorbid
disease was defined as present if it appeared in the
records of the index admission (the admission for
primary acute urinary retention) or of admissions that
occurred in the six months before the index admission.
Statistical analysis
We used the Kaplan-Meier method to estimate age
specific mortality within 90 days and one year after
primary acute urinary retention. To compare mortality
within the first year with that of men in the general
population, we calculated standardised mortality ratios
according to age and comorbidity. Standard rates were
mortalities specific for age group and calendar year for
men in the general population of England for
1999-2005. The standardised rates were calculated by
dividing the mid-year estimate of the number of men
within an age group alive in England and Wales by the
number that died during that year. The confidence
intervals for the standardised mortality ratios were
obtained using Byar’s approximation.16
RESULTS
From 1 October 1998 to 31 March 2005, 176 046 men
were admitted to NHS hospitals with a diagnosis of
primary acute urinary retention (table 1). Of these
men, 100 067 (56.8%) had spontaneous acute urinary
retention (mean age 73.5 (SD 10.5) years) and 75 979
(43.2%) had precipitated retention (mean age 74.5 (SD
10.9) years). In all age groups, mortality was higher in
men with precipitated acute urinary retention.
Overall, 14.7% of men with spontaneous acute
urinary retention and 25.3% men with precipitated
acute urinary retention died within the first year
(table 1). About half of these deaths (54.9%) occurred
within the first 90 days.
In men with spontaneous acute urinary retention,
mortality at one year increased strongly with age,
from 4.1% in patients aged 45-54 to 32.8% in those
aged 85 and over (table 1). In men with precipitated
acute urinary retention, mortality at one year increased
Table 1 | Age specific mortality within 90 days and one year after spontaneous and precipitated primary acute urinary retention
and standardised mortality ratios (SMR) against the general population of England
Mortality
Age group
Total
admissions
90 days
1 year
Deaths
Rate (95% CI)
Deaths
Rate (95% CI)
SMR
(95% CI)
10.0 (8.8 to 11.5)
Spontaneous acute urinary retention
45-54
5 580
119
2.2 (1.8 to 2.6)
216
4.1 (3.6 to 4.6)
55-64
13 918
329
2.4 (2.2 to 2.7)
692
5.3 (4.9 to 5.7)
5.0 (4.6 to 5.4)
65-74
30 661
1 301
4.3 (4.1 to 4.5)
2 822
9.7 (9.4 to 10.1)
3.3 (3.2 to 3.4)
75-84
36 086
2 752
7.8 (7.5 to 8.0)
6 070
17.9 (17.4 to 18.3)
2.3 (2.2 to 2.3)
≥85
13 822
2 153
15.8 (15.2 to 16.4)
4 315
32.8 (32.0 to 33.7)
1.7 (1.6 to 1.7)
Total
100 067
6 654
6.7 (6.5 to 6.8)
14 115
14.7 (14.5 to 14.9)
2.2 (2.2 to 2.3)
Precipitated acute urinary retention
page 2 of 5
45-54
4 979
276
5.6 (5.0 to 6.3)
453
9.5 (8.7 to 10.4)
23.6 (21.5 to 25.9)
55-64
8 736
625
7.2 (6.7 to 7.8)
1 043
12.5 (11.8 to 13.2)
12.0 (11.3 to 12.8)
65-74
20 461
2 095
10.3 (9.9 to 10.8)
3 492
17.8 (17.3 to 18.3)
6.1 (5.9 to 6.3)
75-84
28 148
4 551
16.4 (15.9 to 16.8)
7 711
28.7 (28.1 to 29.2)
3.7 (3.6 to 3.8)
≥85
13 655
3 792
28.0 (27.3 to 28.8)
5 983
45.4 (44.6 to 46.3)
2.4 (2.3 to 2.4)
Total
75 979
11 339
14.8 (14.6 to 15.1)
18 682
25.3 (24.9 to 26.3)
3.5 (3.5 to 3.6)
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RESEARCH
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to a similar extent in the corresponding age groups
from 9.5% to 45.4%.
Although the highest one year mortality was
observed in the oldest age groups, the age specific relative increase in mortality was highest in the youngest
age groups (table 1). In men aged 45-54 years, compared with the general population there was a 10-fold
increase in mortality in those with spontaneous acute
urinary retention and an almost 24-fold increase in
mortality in men with precipitated acute urinary retention. The corresponding increases in men aged 85 and
over were 1.7-fold and 2.4-fold, respectively.
More than a third of men with acute urinary retention had at least one major comorbid condition as
defined by the Charlson score (table 2). As expected,
comorbidity was more prevalent in men with precipitated rather than acute urinary retention (43.5% v
29.1%). The presence of comorbidity greatly increased
mortality. For example, in men with spontaneous acute
urinary retention aged 75-84 years, the most prevalent
age group, the presence of comorbidity more than
doubled the one year mortality, from 12.5% to
28.8%. In men with precipitated acute urinary retention in the corresponding age group, the presence of
comorbidity had a similar effect, and one year mortality increased from 18.1% to 40.5%.
One year mortality was high in men with comorbidity in the oldest age group (44.3% in spontaneous and
54.7% in precipitated acute urinary retention). The age
specific relative increase compared with the general
population, however, was again highest in the youngest age group (standardised mortality ratio 36.5 v 60.4,
respectively).
Even in men without comorbidity as defined by the
Charlson score, mortality within the first year after
acute urinary retention was considerably higher than
in the general population (table 2). For example, in
men with spontaneous acute urinary retention without
comorbidity, mortality was 4.4 times higher than in the
general population in the youngest age group and 1.4
times higher in the oldest age group. Similarly, in men
with precipitated acute urinary retention without
comorbidity, mortality was 8.4 times higher in the
youngest age group and 2.0 times higher in the oldest
age-group.
DISCUSSION
Mortality after primary acute urinary retention in men
admitted to hospital is high. Overall, we found that one
in seven men with spontaneous acute urinary retention
and one in four with precipitated acute urinary retention died in the first year. Mortality increased strongly
with age and the presence of comorbidity. Consequently, about half of the men aged 85 and over with
at least one comorbid condition died within the first
year after acute urinary retention. Although mortality
in men under 55 without comorbidity is not as high, it
was still at least four times higher than that observed in
men of similar age in the general population.
Methodological limitations
We included only men who were admitted to hospital
and did not consider those who were treated within
primary care or solely in a hospital emergency department. Those patients might have been in a better overall condition than the patients who were admitted.
According to a 2004 survey, however, only 10% of
UK urologists would not admit men presenting with
acute urinary retention.17 Also, a Dutch epidemiological study, the only population based study to date in
which the incidence of acute urinary retention was estimated through direct access to a prospectively collected primary care database, reported an incidence
of 2.2 per 1000 men per year.3 This is lower than the
incidence of 3.1 per 1000 men per year that we
reported previously based on hospital admissions in
England.4 We therefore consider it unlikely that we
missed a substantial number of men.
Table 2 | Age specific mortality within one year after spontaneous and precipitated primary acute urinary retention and
standardised mortality ratios (SMR) with and without comorbidity
Men with comorbidity (Charlson score ≥1)
Men without comorbidity (Charlson score 0)
Age
group
Total
admissions
1 year
Deaths
Rate (95% CI)
SMR (95% CI)
Total
admissions
1 year
Deaths
Rate % (95% CI)
SMR (95% CI)
Spontaneous acute urinary retention
45-54
4 590
77
1.8 (1.4 to 2.2)
4.4 (3.4 to 5.4)
990
139
14.7 (12.6 to 17.2)
36.5 (30.7 to 43.1)
55-64
10 987
232
2.3 (2.0 to 2.6)
2.1 (1.9 to 2.4)
2 931
460
16.7 (15.4 to 18.2)
15.8 (14.4 to 17.4)
65-74
21 981
1 099
5.3 (5.0 to 5.6)
1.8 (1.7 to 1.9)
8 680
1 723
21.0 (20.1 to 21.9)
7.1 (6.8 to 7.4)
75-84
24 155
2 843
12.5 (12.1 to 13.0)
1.6 (1.5 to 1.6)
11 931
3 227
28.8 (27.9 to 29.6)
3.7 (3.5 to 3.8)
≥85
9 268
2 400
27.3 (26.4 to 28.2)
1.4 (1.3 to 1.4)
4 554
1 915
44.3 (42.8 to 45.8)
2.3 (2.2 to 2.4)
Total
70 981
6 651
9.9 (9.7 to 10.2)
1.6 (1.5 to 1.6)
29 086
7 464
27.2 (26.7 to 27.7)
3.7 (3.6 to 3.8)
Precipitated acute urinary retention
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45-54
3 522
114
3.4 (2.9 to 4.1)
8.4 (6.9 to 10.1)
1 457
339
24.3 (22.1 to 26.6)
60.4 (54.2 to 67.2)
55-64
5 496
235
4.5 (4.0 to 5.1)
4.3 (3.8 to 4.9)
3 240
808
26.0 (24.5 to 27.6)
25.1 (23.4 to 26.9)
65-74
11 426
880
8.1 (7.6 to 8.6)
2.7 (2.6 to 2.9)
9 035
2 612
30.0 (29.1 to 31.0)
10.3 (9.9 to 10.7)
75-84
14 869
2 571
18.1 (17.5 to 18.8)
2.3 (2.2 to 2.4)
13 279
5 140
40.5 (39.6 to 41.3)
5.2 (5.1 to 5.4)
≥85
7 578
2 778
38.0 (36.9 to 39.2)
2.0 (1.9 to 2.0)
6 077
3 205
54.7 (53.4 to 55.9)
2.8 (2.7 to 2.9)
Total
42 891
6 578
16.1 (15.7 to 16.4)
2.3 (2.2 to 2.3)
33 088
12 104
38.1 (37.6 to 38.6)
5.0 (4.9 to 5.1)
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RESEARCH
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The Charlson score based on administrative data
underestimates the prevalence of comorbid
disease.18 19 Undetected comorbidity may account for
our observation that men without comorbidity
according to the Charlson score still had a higher
mortality than the general population. None the less,
we found that the Charlson score identified at least one
comorbid condition in more than a third of men with
acute urinary retention and that mortality was most
increased in this group. A more accurate instrument
could have shown an even more marked impact of
comorbidity.
The reported mortality after acute urinary retention
was based on the linkage between the HES database of
all admissions to NHS hospitals in England and the
mortality database of the Office for National Statistics.
Most (96%) patients had a date of death that was based
on robust linkage methods that relied on an exact
match of at least two of the NHS number (a unique
10 digit code allocated to an individual to enable
identification for NHS health care), date of birth, and
postcode. For these patients, we found contradictory
linkage results (that is, an admission date after a date
of death) in only 0.3% of patients. In the 4% of patients
remaining, we used a less robust linkage method
(partial match of date of birth and exact agreement of
sex and postcode) and found contradictory results in
54% of the patients. As explained before, we assumed
that men with contradictory mortality results were
alive until the end of the study period. Sensitivity
analyses of alternative assumptions showed that the
mortality for all men within one year after acute
urinary retention always changed by less than
0.5 percentage point, and in turn the relative increases
in mortality compared with the general population did
not change appreciably.
Comparison with other studies
We specifically looked at longer term mortality after
acute urinary retention. The only other study to date
that provides some evidence on mortality after acute
urinary retention was carried out in five healthcare
regions in the UK in the mid-1990s in 3966 men who
underwent prostatic surgery.20 That found that the
1242 men who underwent a prostatectomy after acute
urinary retention had a higher mortality in the first
90 days (3.0%) compared with the 2724 men who had
surgery for symptoms alone (0.7%). Other studies that
have reported on outcomes after acute urinary
retention tend to focus only on recurrence and the
need for prostatic surgery.4 12
Acute urinary retention shares several characteristics with fractured neck of femur. Both are acute and
serious age related events that almost always result in
hospital admission but do not directly cause death.
Two English studies have recently reported the one
year mortality in men after fractured neck of femur to
be just over 40%.21 22 Mortality clearly increased with
age from 20% in men aged 65-69 to 50% in men aged
85-89.21 Comorbidity was found to be an important
page 4 of 5
predictor of outcome, with mortality in the first year
about 1.5 times higher in patients with at least one
comorbid condition than in patients without
comorbidity.22
The comparison with fractured neck of femur shows
that acute urinary retention constitutes a health
problem of a similar magnitude. The overall one year
mortality was 20%, which is lower than that observed
after fractured neck of femur. The incidence of primary
acute urinary retention, however, is 3.1 per 1000 men
per year, which is higher than the incidence of
fractured neck of femur, estimated to be about 2.4 per
1000 men per year based on the HES database.
Explanations for the increased mortality
Though acute urinary retention is generally considered a urological emergency, serious consequences
are rare with appropriate treatment. Our finding of a
high mortality in the first year seems to contradict this.
An obvious explanation for the increased mortality is
that occurrence exposes men to risks associated with
admission to hospital, catheter related and other
nosocomial infections, and invasive procedures that
often need a general anaesthetic.
While these factors do play a role, the high mortality
seems to be linked mainly to comorbidity for several
reasons. Firstly, the presence of comorbidity according
to the Charlson score substantially increased mortality
within patients of similar age and with the same type of
acute urinary retention. Secondly, mortality was also
higher in patients with precipitated rather than
spontaneous retention. Precipitated retention occurs
after a triggering event that is unrelated to the prostate
and therefore a further indication of comorbidity.
Thirdly, there seems to be a “dose-response” relation
as the lowest mortality was found in patients with
spontaneous retention and no comorbidity according
to the Charlson score and the highest mortality in
patients with precipitated retention and comorbidity.
Lastly, a detailed inspection of the diagnostic fields in
patients with spontaneous acute urinary retention and
no comorbidity apparent showed that 58% of these
patients had at least one diagnosis not related to the
prostate and not captured by the Charlson score.
Of the patients who had comorbidity according to
the Charlson score, irrespective of the type of acute
urinary retention, about 30% had cardiovascular
disease, 25% diabetes, 25% chronic pulmonary
disease, and 15% a malignancy. The relatively high
prevalence of cardiovascular disease and diabetes is
consistent with the findings of recent aetiological
studies linking hypertension and metabolic syndrome
with the progression of benign prostatic hyperplasia.7 8
Clinical implications
The high mortality that we observed in men admitted to
hospital with acute urinary retention shows that they are
a vulnerable group of patients. These observations reinforce the importance to the clinician of adopting a multidisciplinary approach in the assessment and
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WHAT IS ALREADY KNOWN ON THIS TOPIC
The incidence of acute urinary retention strongly increases with age
Acute urinary retention seems to be associated with severe systemic disease
WHAT THIS STUDY ADDS
One in seven men admitted to hospital with spontaneous acute urinary retention and one in
four with precipitated acute urinary retention die within a year
Mortality is considerably higher in older men and in those with comorbidity
Patients with acute urinary retention are a vulnerable group and may benefit from urgent
multi-disciplinary care to identify and treat comorbid conditions
Funding: JNA was supported by the Bob Young Research Fellowship, the
Dunhill Medical Trust, and the Royal College of Surgeons of England research
fellowship scheme. JvdM received a national public health career scientist
award from the Department of Health and NHS research and development
programme.
Competing interests: None declared.
Ethical approval: Not required.
Provenance and peer review: Not commissioned; externally peer reviewed.
1
2
3
management of such patients.23 Men with acute urinary
retention should undergo a comprehensive investigation for comorbid disease. The extent to which mortality
after acute urinary retention can be reduced, however,
will depend on the nature and severity of the comorbidities involved and the effectiveness of the available treatments. For example, some patients will have
comorbidity that is already optimally treated and for
whom little further can be done.
Our observation that about half of the deaths after
acute urinary retention occur within the first 90 days
suggests that assessment of comorbidity must occur
promptly. Indeed, perhaps screening for other
morbidities should start in men presenting with lower
urinary tract symptoms attributable to benign prostatic
hyperplasia before they experience acute urinary
retention.
4
5
6
7
8
9
10
11
12
Research implications
The two most important unanswered questions relate
to the way in which comorbidities can be identified and
the extent to which their treatment will reduce mortality after acute urinary retention. In our view, research
building on administrative databases, such as the
hospital episode statistics, enriched through linkage
with additional clinical data seems to be the obvious
next step to answer both questions. Firstly, administrative databases can provide near complete follow-up in
terms of further treatment as well as death. Clinical
data, perhaps collected prospectively in a subgroup
of patients and linked to the administrative data at the
individual patient level, will allow a further exploration
of the impact of comorbidity according to its nature
and severity. The results of this will inform the
development of treatment strategies. Secondly, these
strategies can then be evaluated with research designs
that build on combining administrative data with data
derived from clinical trials.
We thank the Department of Health for providing the hospital episode statistics
data used in this study and Jim Lewsey, statistician at London School of Hygiene
and Tropical Medicine and the Royal College of Surgeons of England, for his
help with the extraction of the dataset.
13
14
15
16
17
18
19
20
21
22
23
Contributors: JNA, PJC, ME, and JHvdM designed the study; JNA and NS
conducted the statistical analyses; JNA and JHvdM drafted the paper; NS, PJC,
and ME commented on and contributed to the final version. JHvdM is guarantor.
BMJ | ONLINE FIRST | bmj.com
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Accepted: 7 October 2007
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