The prevalence of urinary incontinence has been found to vary with age. A prevalence peak in midlife has been reported by many authors,1–5 implicating menopause as a cause. The prevalence of urinary incontinence reported in women during the menopausal transition varies from 8%6 to 56%,4,6 depending on the operational definition of incontinence and the sample population. Although menopause has been shown to be associated with urinary incontinence,1,2,7–9 evidence for it being an independent factor in the prevalence of urinary incontinence is lacking. These studies, which have found an association, have been cross-sectional. Information from prospective studies is required.
The postmenopausal hypoestrogen state has been associated with anatomic and physiologic changes such as thinning of the urethral mucosa, loss of urethral closure pressure, and alteration of the normal urethrovesical angle, factors themselves associated with urinary incontinence.10 Other variables have been shown to be associated with urinary incontinence either alone, or clustered: age,5 parity,11 urinary tract infections,7 body mass index (BMI),12 constipation,13 psychologic well-being,14 lifestyle factors,15 arthritic diseases,16 hysterectomy, and some gynecologic surgery.17 Their association with urinary incontinence within the menopausal transition, however, is less clear.
The aims of this study were: (1) to estimate the prevalence of urinary incontinence among a population-based sample of Australian women aged 45–55 years (the Melbourne Women's Midlife Health Project), and to identify the factors associated with urinary incontinence; (2) to estimate the incidence of urinary incontinence over 7 years of follow-up in a cohort of premenopausal women from this sample, and to identify whether the transition from pre- to postmenopause is associated with the development of urinary incontinence.
MATERIALS AND METHODS
The study was approved by the Human Research Ethics Committee of the University of Melbourne. The study was in two parts: (1) a cross-sectional phase involving 1897 women aged 45–55 years; and (2) a longitudinal 7-year follow-up phase, which assessed a cohort of 373 women from the cross-sectional study who were pre-menopausal at the first follow-up year.
A population-based sample of 1897 Melbourne women,18 contacted by random selection of telephone numbers, who were Australian-born and aged between 45–55 years participated in the baseline interview. Women were eligible for the longitudinal study if they had menstruated in the previous 3 months, had an intact uterus and at least one ovary, and were not currently taking oral contraceptives or hormone replacement therapy (HRT). From an original 1897 women, 779 met these criteria, of whom 438 (56%) agreed to be interviewed in the first year of the longitudinal study. Participants were significantly more likely than eligible nonparticipants to: report better health compared with women of the same age; be in paid employment; have had more than 12 years of education; have had a Papanicolaou smear; to exercise once a week, and to have undergone dilatation and curettage.19
Baseline data obtained in the cross-sectional phase of the Melbourne Women's Midlife Health Project were from telephone interviews. The core questionnaire18,20 obtained information on a number of variables, including: age, weight, height, well-being, lifestyle factors (smoking, frequency and type of physical activity), reproductive and menstrual histories, gynecologic surgery, chronic health conditions, medications, HRT use, symptoms of bladder infections, and diarrhea or constipation. Participants were asked about common health problems, which “have bothered them during the last 2 weeks,” and one of these was “problems with urine control.” Women who answered “yes” to this problem were classified as having urinary incontinence. Women were defined as having a urinary tract infection if they had been bothered by “bladder infection problems.”
The longitudinal study consisted of annual face-to-face interviews of the 438 women, and these were conducted in the women's homes when questionnaires were administered and physical measurements taken. The questions on health problems, including problems with “control of your urine in the past 2 weeks” asked annually, were identical to those asked in the initial telephone interview. At the final year of follow-up, further questions were asked on urinary control problems. These included whether the problem was one of urinary urgency—not getting to the toilet on time, or stress incontinence—“wetting” when you cough, sneeze, jump, or lift. The Personal Experiences Questionnaire21 was administered to provide information on sexual functioning.
Menopausal status was determined by menstrual history reported at the time of the interview. Women were defined as premenopausal if they reported no change in menstrual frequency in the prior 12 months, perimenopausal if they reported changes in menstrual frequency or 3–11 months of amenorrhoea, and naturally postmenopausal if they reported amenorrhoea for 12 consecutive months or more. The use of HRT was recorded at the time of interview. Women were defined as surgically menopausal if they had experienced a hysterectomy and/or bilateral oophorectomy or an endometrial ablation.
Bivariate analysis (using χ2 and t tests) identified those explanatory variables associated with urinary incontinence at a significance level of 0.10. These were entered in a logistic regression analysis with a 0.05 level of significance adopted for retention in the model. Parity was defined as an ordinal variable: no children, one or two children, three or more children, and BMI was categorized into two groups: less than 26 kg/m2 and equal to or greater than 26 kg/m2. Comparisons between menopausal and menopausal transition groups were made using analysis of variance. Women who developed urinary incontinence were compared with those who did not using χ2, t tests, and logistic regression analysis.
The cross-sectional cohort comprised 1897 women, mean age 49.7 (standard deviation [SD] 3.1, range 45–55 years), of whom 471 (25%) were premenopausal, 393 (21%) were perimenopausal, 355 (19%) were postmenopausal, 248 (13%) were using HRT, and 429 (23%) had experienced a surgical menopause at the time of the telephone interview. Of the 429 women in the surgical menopausal group, 156 (36%) were taking HRT. The prevalence of urinary incontinence in the 1897 women was 15% (CI 13%, 17%). Table 1 shows the demographic characteristics of the population according to whether they reported urinary incontinence or not. There was no significant difference between the two groups as regards these variables.
Table 2 shows the prevalence of urinary incontinence by menopausal status. Urinary incontinence was more prevalent in perimenopausal, HRT, and surgical menopausal groups compared with the premenopausal group (P < .005). The prevalence of urinary incontinence in surgically menopausal women was 18% (CI 14%, 21%) overall, being 23% (CI 17%, 29%) in those surgically menopausal women who were using HRT and 15% (CI 11%, 19%) in nonusers.
In the baseline cohort (age range 45–55 years), no significant association was found between urinary incontinence and age. Stratifying the cohort by menopausal status found that premenopausal women with urinary incontinence were older (P < .05) than those who did not report urinary incontinence (48.5 versus 47.5 years). In the postmenopausal group, women who reported urinary incontinence were younger (P < .05) than those who did not report urinary incontinence (51.1 versus 52.1 years). In the perimenopausal, HRT, and surgical menopausal groups, there was no significant difference in age between those who reported urinary incontinence and those who did not.
Multivariate analysis found that compared with women who did not report urinary incontinence, the urinary incontinence sufferers were significantly more likely to: have a BMI of at least 26 kg/m2 (34% versus 22%); have had gynecologic surgery other than tubal ligation, cesarean section, or hysterectomy (19% versus 10%); report suffering from urinary tract infections (8% versus 1%), diarrhea or constipation (23% versus 11%), arthritis (44% versus 33%); participate in lawn bowls (5% versus 2%); report higher mean negative mood score (0.81 versus 0.68); and to have had three or more children (61% versus 52%). Odds ratios and 95% confidence intervals are shown in Table 3. Menopausal status, including the surgical menopausal group, was not a significant variable in the mutivariate model.
To prospectively study problems with control of urine and the menopausal transition, analysis was completed on data from the first to final follow-up years. Excluded from the longitudinal cohort (n = 438) were women who: had dropped out (n = 51); had missing data over the study period (n = 6); were postmenopausal (n = 6); or had experienced a surgical menopause (n = 2) at the first year of follow-up. This left a cohort of 373 participants who at the first follow-up year had a mean age of 49.5 (SD 2.5, range 47–57 years), 88% had menstruated in the last 3 months, and 12% were using HRT. The women who dropped out were significantly different with respect to two variables only—they were less likely: to be married or live with partner (65% versus 81%, P < .01); or to exercise at least once per week (53% versus 70%, P < .05).
At the first follow-up year, the prevalence of urinary incontinence was 17% (CI 13%, 21%) and at the final year, the prevalence was 19% (CI 15%, 23%). The average prevalence during the 7-year study period was 18%. However, combining the data from each year of the follow-up, 173 (46%) women reported a problem with control of their urine on one or more occasions. Two hundred women (54%) never reported problems with control of their urine. Table 4 shows the incidence of urinary incontinence by menopausal transition group over the 7-year follow-up period, with an incidence rate of 35%. There was no association between the development of urinary incontinence and the transition to postmenopause. Women who experienced a surgical menopause had higher incidence of urinary incontinence than women in the other menopausal transition groups.
Women who reported urinary incontinence more often (5 or more years) had a higher mean BMI at the first follow-up year compared with women who never reported urinary incontinence (SD 27.2, 5.3 kg/m2 versus SD 25.5, 4.7 kg/m2, P = .054). There was no significant difference between the weight gains of the two groups during the study period. There was a correlation between reporting urinary incontinence and urinary tract infections over the 7-year follow-up period (P < .05). In the final year of follow-up, the most common urinary incontinence problem reported was stress incontinence (64%), compared with urge incontinence (37%). There was a trend for urinary incontinence sufferers to report that their normal occupation involved moderate to excessive labor (P = .078). Women who reported urinary incontinence had fewer sexual thoughts and fantasies (P < .01). Smoking was not related to incidence of urinary incontinence; neither was there an association with smokers who reported of a chronic cough.
The prevalence of urinary incontinence and the factors associated with it were studied in a population-based cohort of 1897 Australian women with a 7-year follow-up of 373 who were premenopausal at baseline. An overall prevalence rate of 15% was found in the cross-sectional cohort. In the longitudinal cohort, no significant association was found between urinary incontinence and the transition to postmenopause.
The cross-sectional prevalence rate was in the midrange of prevalence rates for women aged 45–55 years reported in other studies.4,5 The prevalence rate differences between different study cohorts can probably be explained by the different questions asked and the methodology of the surveys. The prevalence figures for urinary incontinence obtained in this study were gained from women recalling incontinence symptoms within the last 2 weeks. This time frame was recent enough to elicit an accurate response with regard to the presence of urinary incontinence, unlike other studies4,22 where the recall time was within the last 12 months.
Limitations to this study include the wording of the question used to determine urinary incontinence, and not determining the type of incontinence in the cross-sectional study. The question we used had been validated and used in other population-based studies.23 A recent study24 of middle-aged women using a question, which asked about “leaking” urine, reported associations of urinary incontinence with similar variables to the current study.
At baseline, women taking HRT, women who had experienced a hysterectomy, and perimenopausal women had significantly higher prevalence of urinary incontinence than premenopausal women. As these results were cross-sectional, we can only report associations not causation. In the multivariate model, menopausal status was not a significant variable when comparing urinary incontinence sufferers with nonsufferers. The high prevalence among hormone users (19%) may have been because they were prescribed HRT for this problem. The high prevalence in the women who have had a hysterectomy has also been shown in other studies.7,17 This association in our cohort may be attributed to other factors not examined in this study. Women who have a hysterectomy are more likely to have had previous dilatation and curettage procedures, used more prescription medication, and have pre-existing health problems.25 A recent case control study revealed that women who had experienced a hysterectomy had a higher prevalence of severe stress incontinence (intrinsic sphincter deficiency) than controls matched for age, parity, and previous surgery.26 In our longitudinal study, the women who experienced a hysterectomy had a higher incidence of urinary incontinence. This may reflect factors other than their surgery, but with the small group, no significant associations were found.
Urinary symptoms did appear to be a significant problem during the perimenopause. This is the time of the menopausal transition when the hormone status of women is most volatile, estrogen levels are decreasing, and FSH increasing,27 and there is a rise in symptom reporting.10 In our study, age did not appear to be associated with urinary incontinence. However, the age range studied, 45–55 years at baseline and 53–64 years at follow-up, may have been too narrow to permit conclusions about the association between age and urinary incontinence. In the baseline cohort, the older premenopausal and younger postmenopausal women were more likely to report urinary incontinence, which is probably not an association with age per se, but with the proximity of the perimenopausal period. Separating aging and hypoestrogen effects has proved to be a major limitation of research about urinary incontinence. Fantl et al28 suggest that hypoestrogenism may be one of several factors involved in the aging process and a contributory rather than a single causative factor in the development of urinary incontinence.
It was interesting to note that the most significant factors affecting urinary incontinence in the present study were mechanical rather than hormonal changes associated with the menopause. Multivariate analysis of the baseline cohort showed that a high BMI, parity, and having diarrhea or constipation were significantly associated with urinary incontinence. In the 7-year follow-up cohort, moderate to excessive exertion in the workplace had a tendency to be associated with the development of urinary incontinence as did a high BMI. A high BMI, multiple pregnancies, straining with bowel motions, and lifting/carrying appear to cause mechanical stress on the urogenital tissues. Over time, the collagen support in the pelvic fascia and ligaments weakens and may cause pelvic organ prolapse, which can affect urinary continence.29 Pudendal nerve damage has also been reported with acute and chronic straining.13
Sexual dysfunction has been linked with urinary incontinence previously.30 The basis for the relationship has not been specifically investigated. Our study revealed that women with urinary incontinence had fewer sexual thoughts and fantasies, indicating that urinary incontinence might be associated with decreased libido. Lawn bowls, a low intensity form of exercise, involves bowling in a half kneeling position on an outdoor grass rink, and might attract women with incontinence problems because of the gentle nature of this exercise. Other variables found to be associated with urinary incontinence included negative mood, arthritis, and urinary tract infection, confirming other studies.16,24,31 The etiology of the relationship between urinary incontinence and arthritis needs further research.
The effect of hormone therapy on incontinence is controversial. Fantl et al32 reported that estrogen therapy relieved the symptoms of urge incontinence, urinary frequency, and nocturia, but had less of an effect on stress incontinence. Grady et al33 found no improvement in the frequency of stress or urge incontinence among women treated with combined conjugated estrogen and progestin therapy. Stress incontinence was the most common type of urinary incontinence experienced by our longitudinal cohort, and our study suggests this is more likely to be from a mechanical cause such as chronic constipation, obesity, parity, or exertion, rather than hormonal.
In the longitudinal study, 46% of the cohort were bothered by problems of urinary incontinence at some time, although on a yearly basis the average prevalence was 18%. It appears that some women only have what might be called “transient incontinence,” but it is a bothersome problem for them. This transitory incontinence could have a number of causes, but we have not been able to significantly identify any one mechanism, or it might be the beginning of a problem that will become chronic as the women age.
This prospective study found that becoming postmenopausal was not associated with increased incidence of urinary incontinence. The finding that a high proportion of women in the age range 46–64 years suffer at some time from problems with urine control identifies urinary incontinence as a major public health problem. Greater awareness of the prevalence of urinary incontinence in middle-aged women, greater efforts to identify sufferers, and more public health literature about health and lifestyle factors influencing urinary incontinence could lead to an improved quality of life for many middle-aged and elderly women.
1. Sommer P, Bauer T, Nielson KK, Kristensen ES, Hermann G, Steven K, et al. Voiding patterns and prevalence of incontinence in women. A questionnaire survey. Br J Urol 1990;66:12–5.
2. Harrison GL, Memel DS. Urinary incontinence in women: Its prevalence and its management in a health promotion clinic. Br J Gen Practice 1994;44:149–52.
3. Dolan LM, Casson K, McDonald P, Ashe RG. Urinary incontinence in Northern Ireland: A prevalence study. BJU International 1999;83:760–6.
4. Yarnell JWG, Voyle GJ, Richards CJ, Stephenson TP. The prevalence and severity of urinary incontinence in women. J Epidemiol Comm Health 1981;35:71–4.
5. Thomas TM, Plymat KR, Blannin J, Meade TW. Prevalence of urinary incontinence. BMJ 1980;281:1243–5.
6. Larson B, Collins A, Landgren BM. Urogenital and vasomotor symptoms in relation to menopausal status and the use of HRT in healthy women during transition to menopause. Maturitas 1997;28:99–105.
7. Rekers H, Drogendijk AC, Valkenburg HA, Riphagen F. The menopause, urinary incontinence and other symptoms of the genitourinary tract. Maturitas 1992;15:101–11.
8. Stenberg A, Heimer G, Ulmsten U, Cnattingius S. Prevalence of genitourinary and other climacteric symptoms in 61-year old women. Maturitas 1996;24:31–6.
9. Dennerstein L, Dudley EC, Hopper JL, Guthrie JR, Burger HG. A prospective population-based study of menopausal symptoms. Obstet Gynecol 2000;96:351–8.
10. Schaffer J, Fantl JA. Urogenital effects of the menopause. Bailliere's Clin Obstet Gynaecol 1996;10:401–17.
11. Ryhammer AM, Laurberg S, Hermann AP. Long term effect of vaginal deliveries on anorectal function in normal perimenopausal women. Dis Colon Rectum 1996;39:852–9.
12. Dwyer P, Lee ETC, Hay DM. Obesity and urinary incontinence in women. Br J Obstet Gynaecol 1988;95:91–6.
13. Snooks SJ, Swash M, Henry MM, Setchell M. Risk factors in childbirth causing damage to the pelvic floor innervation. Br J Surg 1985;72:s15–s17.
14. O'Dowd TC. Urinary incontinence in women — a conundrum. Br J Gen Practice 1994;44:147–8.
15. Bump RC, McClish DK. Cigarette smoking and urinary incontinence in women. Am J Obstet Gynecol 1992;167:1213–8.
16. George GHM, Spector TD. Arthritis, menopause and estrogens. In: Wren BG, ed. Progress in the management of the menopause. Proceedings of the 8th International Congress on the Menopause, Sydney, November 1996. New York: Parthenon Publishing Group, 1997.
17. Milsom I, Ekelund P, Molander U, Arevidsson L, Areskoug B. The influence of age, parity, oral contraception, hysterectomy and menopause on the prevalence of urinary incontinence in women. J Urol 1993;149:1459–62.
18. Dennerstein L, Smith AMA, Morse CA, Burger HG, Green A, Hopper JL, et al. Menopausal symptoms in Australian women. Med J Aust 1993;159:232–6.
19. Burger HG, Dudley EC, Hopper JL, Shelley JM, Green A, Smith A, et al. The endocrinology of the menopausal transition: A cross-sectional study of a population-based sample. J Clin Endocrinol Metab 1995;80:3537–45.
20. Dennerstein L, Smith AMA, Morse CA. Psychological well-being, mid-life and the menopause. Maturitas 1994;20:1–11.
21. Dennerstein L, Dudley E, Hopper JL, Burger HG. Sexuality, hormones and the menopausal transition. Maturitas 1997;26:83–93.
22. Diokno AC, Brock BM, Brown MB, Herzog AR. Prevalence of urinary incontinence and other urological symptoms in the non-institutionalized elderly. J Urol 1986;136:1022–5.
23. McKinlay SM, Brambilla DJ, Posner J. The normal menopause transition. J Hum Biol 1992;4:103–15.
24. Chiarelli P, Brown W, McElduff P. Leaking urine: Prevalence and associated factors in Australian women. Neurourol Urodynam 1999;18:567–7.
25. Dennerstein L, Shelley J, Smith AMA, Ryan M. Hysterectomy experience among mid-aged Australian women. Med J Aust 1994;161:311–3.
26. Morgan JL, O'Connell HE, McGuire EJ. Is intrinsic deficiency a complication of simple hysterectomy? J Urol 2000;164:767–9.
27. Burger HG, Dudley E, Hopper JL, Groome N, Guthrie JR, Green A, et al. Prospectively measured levels of serum FSH, estradiol and the dimeric inhibins during the menopausal transition in a population-based cohort of women. J Clin Endocrinol Metab 1999:84;4025–30.
28. Fantl JA, Bump RC, Robinson D, McClish DK, Wyman JF. Efficacy of estrogen supplementation in the treatment of urinary incontinence. The Continence Program for Women Group. Obstet Gynecol 1996;88:745–9.
29. De Lancey JO. Anatomy and physiology of urinary continence. Clin Obstet Gynecol 1990;33:298–307.
30. Cardozo L. Sex and the bladder. BMJ 1988;296:587–8.
31. Uebersax JS, Wyman JF, Shumaker SA, McClish DK, Fantl JA, and the Continence Program for Women Research Group. Short forms to assess life quality and symptom distress for urinary incontinence in women: The incontinence impact questionnaires and urogenital distress inventory. Neurourol Urodynam 1995;14:131–9.
32. Fantl JA, Wyman JR, Anderson RL. Postmenopausal urinary incontinence: Comparison between nonestrogen-supplemented and estrogen-supplemented women. Obstet Gynecol 1988;71:823–8.
33. Grady D, Brown JS, Vittinghoff E, Applegate W, Varner E, Snyder T, for the HERS Research Group. Postmenopausal hormones and incontinence: The heart and estrogen/progestin replacement study (HERS). Obstet Gynecol 2001;91:116–20.