Leaking urine: Prevalence and associated factors in Australian women

Leaking Urine: Prevalence and Associated
Factors in Australian Women
Pauline Chiarelli, 1 Wendy Brown, 2 * and Patrick McElduff 3
1 Faculty of Medicine and Health Sciences, The University of Newcastle, NSW, Australia
2 Research Institute for Gender and Health, The University of Newcastle, NSW, Australia
3 Department of Statistics, The University of Newcastle, NSW, Australia
The Women’s Health Australia project provided the opportunity to examine the prevalence
of leaking urine and associated variables in three large cohorts of Australian women 18–23
years of age (“young” N � 14,761), 45–50 (“mid-age” N � 14,070), and 70–75 (“older”
N � 12,893). The proportion of women reporting leaking urine was 12.8% (95% CI:
12.2–13.3), 36.1% (35.2– 37.0), and 35% (34.1– 35.9) in each of the three cohorts, respectively.
Logistic regression analysis showed significant associations between leaking urine
and parity in the young and mid-age women, and between leaking urine and constipation,
other bowel symptoms, body mass index, and urine that burns or stings in all three groups.
In the mid-age and older cohorts, women who reported having both hysterectomy and
prolapse repair, or prolapse repair alone, were also more likely to report leaking urine.
Lower scores on the physical and mental component summary scores of the medical outcomes
survey short form (36 items) questionnaire suggest lower quality of life among
women who report leaking urine, compared with those who do not. Neurourol. Urodynam.
18:567–577, 1999. © 1999 Wiley-Liss, Inc.
Key words: female urinary incontinence; parity; gynaecological surgery; constipation
INTRODUCTION
Urinary incontinence (UI) is morbid [Grimby et al., 1993], costly [Fonda, 1992],
and progressive [Ouslander, 1990] and affects women seven to eight times more often
than men [Millard, 1985]. It is often presumed to be a condition experienced only in
old age; one study has estimated that 50% of the 75,000 residents in Australian
nursing homes (70% of whom are women) are “wet” [Millard, 1996]. Indeed, several
epidemiological studies have shown a significant association between UI and older
age [Molander et al., 1990; Burgio et al., 1991; Milsom et al,. 1993]. However, studies
of UI in women across all age groups have estimated the prevalence to be between
25% [Foldspang et al., 1992] and 45% [Yarnell et al., 1981], and one 1985 study of
1,256 community dwelling adults has estimated the prevalence among Australian
women over 10 years of age to be 34% [Millard, 1985].
*Correspondence to: Dr. Wendy J. Brown, Research Institute for Gender and Health, The University of
Newcastle, Callaghan, NSW 2308, Australia. E-mail: whwjb@cc.newcastle.edu.au
Received 25 May 1998; Accepted 20 April 1999
© 1999 Wiley-Liss, Inc.
PROD #1062
Neurourology and Urodynamics 18:567–577 (1999)

568 Chiarelli et al.
Parity is commonly associated with UI [Thomas and Plymat, 1980; Jolleys,
1988; Foldspang et al., 1992; Milsom et al., 1993]. Vaginal delivery has been shown
to induce stretching injury to several structures within the lower part of the bony
pelvis as well as to the pelvic floor muscles, nerves, and connective tissues [Snooks
et al., 1984, 1985b; Swash, 1990]. In many cases, the resultant trauma may lead to
poor support of the pelvic organs. Further insult to the weakened pelvic floor structures
can occur in time by way of increases in abdominal pressure that accompany
such conditions as constipation [Lawrence and Bannister, 1985; Laycock and Jerwood,
1991], chronic coughing or sneezing [Constantinou and Gowan, 1982; Laycock
and Jerwood, 1991], and obesity [Koelbl and Riss, 1987; Wilkie, 1987]. In time these
conditions are thought to lead to pelvic organ prolapse and/or urinary incontinence
[Snooks et al., 1985a; Koelbl and Riss, 1987; Spence-Jones et al., 1994]. Other studies
have suggested an association between urinary incontinence and other dysfunctional
bowel symptoms [Coates et al., 1997; Cukier et al., 1997].
A variety of other factors has also been shown to be associated with female UI.
These include hormonal status, surgery, urinary tract disorders and hereditary factors.
While urinary incontinence is known to be associated with perimenopause, a study of
3,114 Danish women has found that surgical procedures contribute more strongly than
menopause status to the experience of UI in middle aged women [Foldspang and
Mommsen, 1994]. Significant associations between UI and urogynecological surgery
have also been reported by researchers in the United States and the United Kingdom
[Parys et al., 1989; Benson and McLellan 1993; Mommsen et al., 1993].
UI is also markedly increased during acute urinary tract infection (UTI) and
during pregnancy. In another study of Danish women, Mommsen found that women
with UTI are almost six times more likely to experience incontinence [Mommsen et
al., 1994], and Chiarelli has reported the prevalence of incontinence in Australian
women during pregnancy to be 64% [Chiarelli and Campbell, 1997].
UI may also be associated with hereditary factors. Studies of the prevalence of
UI show a significant relationship between incontinent women and their first degree
female relatives [Mushkat et al., 1996], which may be explained by a constitutional
or genetic weakness in the collagen of women with bladder neck prolapse and stress
incontinence of urine [Sayer, 1994].
The Australian Longitudinal Study on Women’s Health [now known as the
Women’s Health Australia (WHA) project] provided an opportunity to determine the
prevalence of leaking urine and associated factors in Australian women. The aims of
this study were to examine the prevalence of the self-report of leaking urine in young,
mid-age, and older Australian women; to assess the associations between leaking
urine and parity, constipation and other bowel problems, body mass index (BMI),
symptoms of UTI, and gynaecological surgery; and to explore differences in health
related quality of life in women who do and do not report leaking urine.
On the basis of previous research, it was hypothesised that the prevalence of
leaking urine would increase with age and that parity, constipation, or other bowel
problems, high BMI, gynaecological surgery, and symptoms of UTI (urine that burns
or stings) would be associated with leaking urine. It was further hypothesised that the
quality of life of women who report leaking urine would be lower than that of other
women.

MATERIALS AND METHODS
The Women’s Health Australia Project
The Women’s Health Australia project aims to examine the relationships between
biological, psychological, social and lifestyle factors, and women’s physical
and emotional health and the use of and satisfaction with health care services. The
project involves three cohorts of women who were young (18–23 years), mid-age
(45–50 years), or older (70–75 years) at the time of the baseline survey. The women
were selected randomly from the national health insurance (Medicare) database,
which includes all women who are resident in Australia, including women from
minority ethnic groups as well as women refugees. Because there is a dearth of
information about women who live outside the metropolitan areas, women who live
in rural and remote areas of Australia were over sampled. Details of the recruitment
methods have been described elsewhere [Brown et al., 1998].
Participants
During 1996, 14,761 young women (48% of those invited to participate), 14,070
mid-age aged women (54%), and 12,893 older women (41%) completed the baseline
surveys for the WHA project. The participants include women from all walks of life,
living in every State and Territory of Australia. They are broadly representative of the
female population of these age groups, but with over-representation of women with
post-school education [Brown et al., 1998].
The Questionnaire and Measures
Leaking Urine in Australian Women 569
The baseline questionnaire consisted of 252, 285, and 260 items, respectively,
for the young, mid-age, and older cohorts. One of the items asked whether women had
experienced leaking urine in the last year. Response options were never, rarely,
sometimes, or often. Responses to this question (those answering rarely, sometimes,
often) were used to estimate the prevalence of leaking urine in each cohort.
Questions about other symptoms, conditions, surgical conditions, and life events
varied for each cohort and included the following: all women—childbirth (number of
times); upper respiratory tract symptoms and conditions (allergies/hay fever/sinusitis,
asthma, breathing difficulties, bronchitis/emphysema); other symptoms that can affect
the pelvic floor (constipation, other bowel problems, body mass index); and symptoms
or conditions that can impact on bladder control (urine that burns or stings, diabetes);
mid age and older women—gynaecological surgery (hysterectomy, removal of both
ovaries, repair of prolapse of the uterus, bladder or bowel); and symptoms or conditions
that can affect on bladder control (going through menopause, currently taking
hormone replacement therapy (HRT), number of years on HRT, taking drugs for
“nerves” or to help with sleeping difficulties, stroke).
Questions about symptoms were prefixed by “In the last twelve months have
you experienced . . . ?,” while questions about conditions and procedures were prefixed
by “Have you ever been told by a doctor that you have ...?”or“Have you ever
had . . . ?.” Questions about medications were prefixed by “In the past four weeks
have you taken ...?.”
The medical outcome survey short form health questionnaire (SF-36) [Ware,
1994] was used to assess general physical and mental health and well-being in each

570 Chiarelli et al.
group. The physical and mental component summary scores (PCS and MCS) were
calculated using the WHA cohort adjustment factors [Mishra and Schofield, 1998].
Data Analysis
Descriptive statistics, mainly proportions and 95% confidence intervals, were
calculated for self report of leaking urine in the three groups. Missing data were
included in the “not leaking” category. For each group univariate analyses were used
to explore associations between clinically plausible variables such as parity, symptoms,
procedures, medications, and leaking urine. Variables that were significantly
associated with leaking urine were then entered into a logistic regression model to
further examine the strength of the associations between leaking urine and each of the
variables, while controlling for the others. Missing data were not included. For the
younger cohort the variables entered into the model were parity, constipation, other
bowel problems, body mass index, and urine that burns or stings. For the mid-age and
older cohorts gynaecological surgery (including removal of both ovaries, hysterectomy,
and repair of prolapsed vagina, bladder, or bowel) was also included. Adjusted
BMI was calculated from self report of height and weight, corrected following the
method of Waters [1993]. Pairwise comparisons of the adjusted mean PCS and MCS
were then computed for women in each cohort who reported leaking urine and those
who did not.
RESULTS
The prevalence of leaking urine in the young, mid-age and older women was
estimated to be 12.8% (CI: 12.2–13.3), 36.1% (CI: 35.2–37.0), and 35% (CI: 34.1–
35.9), respectively.
Associations between self-report of leaking urine in Australian women and
other reported symptoms, conditions, and life events in the younger cohort, the
mid-age cohort, and the older cohort respectively are shown in Tables I–III.
While there was a significant association between leaking urine and parity in the
younger group, this association was lessened by the impact of other conditions such
as surgery in the older groups. In the young cohort, women with children and those
who reported sometimes or often having urine that burns or stings were most likely
to report leaking urine. There was also a strong association between constipation and
leaking urine (Table I).
In the mid-age cohort, women who reported urine that burns or stings, constipation,
and those with high BMI were most likely to experience leaking urine. While
hysterectomy alone was associated with a lower odds ratio for leaking urine, women
who reported prolapse repair either alone or with hysterectomy were more likely to
leak urine (Table II).
In the older cohort, there was no effect for parity but all forms of surgery except
solely hysterectomy were associated with leaking urine. Once again, women with the
highest BMI and those reporting urine that burns or stings and constipation were most
likely to report leaking urine (Table III).
Adjusted mean SF-36 physical and mental component summary scores for each
group are shown in Table IV. While both PCS and MCS scores were significantly

TABLE I. Adjusted Odds Ratios for Variables Associated With Leaking Urine in the
Young Cohort
Variable
lower in all three age groups for women who reported leaking urine, the greatest
differences were seen for MCS scores in the young and mid-age women (Table IV).
DISCUSSION
Never (N)
Leak urine
Rarely,
sometimes, often
(N)
Adjusted a
Odds ratio (95% CI)
Parity
Never 11,460 1,535 1.00
Once 773 290 2.82 (2.37–3.35)
Twice 203 77 2.59 (1.86–3.61)
Three or more 39 25 4.84 (2.54–9.20)
Constipation
Never 8,207 698 1.00
Rarely 2,979 697 2.13 (1.87–2.42)
Sometimes 1,129 412 2.86 (2.43–3.36)
Often 368 150 2.66 (2.07–3.40)
Other bowel problems
Never 11,308 1,462 1.00
Rarely 738 268 1.97 (1.65–2.35)
Sometimes 426 142 1.50 (1.18–1.89)
Often 215 84 1.82 (1.33–2.48)
BMI adjusted
Underweight

572 Chiarelli et al.
TABLE II. Adjusted Odds Ratios for Variables Associated With Leaking Urine in the
Mid-Age Cohort
Variable
Never (N)
Leak urine
Rarely,
sometimes, often
(N)
Adjusted a
Odds ratio (95% CI)
Parity
Never 803 277 1.00
Once 751 405 1.58 (1.29–1.93)
Twice 3,252 1,828 1.66 (1.41–1.95)
Three or more 3,572 2,320 1.81 (1.54–2.12)
BMI adjusted:
Underweight

TABLE III. Adjusted Odds Ratios for Variables Associated With Leaking Urine in the
Older Cohort
Variable
Never (N)
Leak urine
Rarely,
sometimes, often
(N)
Adjusted a
Odds ratio (95% CI)
Parity
Never 726 301 1.00
Once 723 302 0.88 (0.71–1.10)
Twice 1,792 987 1.14 (0.96–1.36)
Three or more 4,278 2,493 1.16 (0.98–1.36)
Constipation
Never 4,758 1,355 1.00
Rarely 1,232 1,227 2.67 (2.38–2.99)
Sometimes 1,206 1,000 2.05 (1.82–2.31)
Often 475 476 2.21 (1.87–2.61)
Other bowel problems
Never 6,292 2,636 1.00
Rarely 509 542 1.48 (1.28–1.72)
Sometimes 536 503 1.39 (1.20–1.62)
Often 240 269 1.51 (1.22–1.87)
BMI adjusted
Underweight

574 Chiarelli et al.
TABLE IV. Means and 95% CI for SF-36 Physical and Mental Component Summary Scores in
Women Who Did and Did Not Report Leaking Urine in Each Group
Leak urine
Young women
(18–23)
N � 14,328
Mid-age women
(45–50)
N � 13,022
Older women
(70–75)
N � 10,464
Physical component
summary score Rarely/sometimes/often 46.5 48.0 48.7
(46.01–46.93) (47.74–48.32) (48.43–49.02)
Never 49.1 50.4 52.2
(48.99–49.28) (50.25–50.62) (51.94–52.37)
Mental component
summary score Rarely/sometimes/often 40.7 44.7 49.7
(40.07–41.23) (44.37–45.08) (49.38–50.01)
Never 46.3 48.5 52.6
(46.05–46.48) (48.19–48.70) (52.30–52.76)
urine, in either the mid-age or older women. Neither current use of HRT nor duration
of use were associated with leaking urine, and adding HRT to the logistic regression
made little difference to the model.
The strong association between leaking urine and reports of “urine that burns or
stings” was not surprising. Since the association was significant for each cohort,
general practitioners might find treatment of UTI an opportune time to raise the issue
of leaking urine with their patients, who may have previously been too embarrassed
to mention that they are experiencing urinary incontinence. Similarly, for women who
do raise the issue of leaking urine, general practitioners might find this an opportune
time to ask about constipation, which was also strongly associated with leaking urine
in each age group in this study. Repeated “straining at stool” is thought to weaken
pelvic floor muscles and ligaments and exacerbate leakage symptoms [Lawrence and
Bannister, 1985; Laycock and Jerwood, 1991]. Prevention of constipation, for example,
by increasing dietary fibre, fluid intake, and physical activity, may therefore
also help to alleviate the symptoms of leaking urine.
In this study there was a direct relationship between leaking urine and BMI.
Other researchers have suggested that increasing pressure on the pelvic floor from
excess weight exacerbates leakage [Koelbl and Riss, 1987; Wilkie, 1987]. In light of
this, health professionals who are encouraging women to make changes to dietary and
activity patterns may be able to add the motivating “reward” of decreased leakage as
an additional benefit of weight reduction strategies. It is also possible however that
leaking urine in the months and years following childbirth may be a barrier to
participation in some forms of physical activity, thus indirectly contributing to the
problem of overweight and obesity in mid-age women.
Researchers from the UK have correlated quality of life assessments using the
SF-36 with urodynamic diagnosis of urinary incontinence in women and concluded
that a number of specific urinary symptoms and urodynamic features are associated
with SF-36 scores [Kelleher et al., 1994; Khullar et al., 1995]. While the lower PCS
and MCS scores for women who reported leaking urine in the present study indicate
an association between well being and leaking urine, these findings do not imply a
direct casual relationship. There are likely to be many confounding factors. For
example, in the young cohort, 9.6% of the women had one or more children. Of these,
35.6% were single parents, and in general these young single mothers reported very

high levels of stress and had low MCS scores. The findings may therefore reflect the
fact that some of the young women with low MCS scores may have had weakened
pelvic floor muscles because of recent childbirth and would therefore be more likely
to experience leaking urine [Viktrup et al., 1992]. It could also be argued that chronic
problems such as diabetes and stroke, which may cause leaking urine [Sotolongo,
1994], might underlie differences in the SF-36 scores between those older women
who reported leaking and those who did not. However, inclusion of these chronic
illnesses in the model for the older women, did not improve the model and there was
no significant association between leaking urine and these problems.
While many studies have looked at the efficacy of treatment protocols for curing
or improving urinary incontinence once it has manifested itself, no studies have
explored the efficacy of continence promotion before incontinence is experienced. In
view of the associations shown here between leaking urine and parity in the young
women, it would seem appropriate to explore opportunities for continence promotion
with young women when they present for pregnancy care. Conservative intervention
at this stage may have multiple benefits in terms of preventing incontinence, constipation,
and possibly prolapse in later years. In view of the high prevalence of leaking
urine among women of all ages, and its likely physical and social sequelae (which
include the need for nursing home care in old age), it is clear that there is now a need
for more promotion and prevention strategies to be trialed and evaluated.
ACKNOWLEDGMENTS
The Australian Longitudinal Study on Women’s Health is funded by the (Australian)
Commonwealth Department of Health and Family Services. The project was
conceived and developed by groups of inter-disciplinary researchers at the Universities
of Newcastle and Queensland, and the contribution of all members of the research
team at the University of Newcastle, particularly the research assistants Joy Goldsworthy
and Lyn Adamson, and data manager Jean Ball, is gratefully acknowledged.
We would like to thank all the participants who contributed to the baseline surveys,
and we are grateful to Kimberley-Clarke Pty, Ltd. for their support of this work.
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