The prevalence of urinary incontinence, especially in elderly women, is estimated to be in the range of 35–45%, although estimates vary greatly.1,2 Urinary incontinence is the eighth most prevalent chronic medical condition among women in the United States.3 Despite its high prevalence, little is known about associated risk factors, and the etiology of urinary incontinence is poorly understood.
One of the main risk factors for developing urinary incontinence is believed to be vaginal birth and the resulting injury to structures within the pelvic floor. The notion that vaginal delivery plays a major role in urinary incontinence has led to an increase in the rate of elective cesarean deliveries in some areas.4 Available data on this presumed relationship between birth trauma and incontinence, however, are conflicting. Although some population-based studies show an association between parity and urinary incontinence,5,6 others do not show such an association.7 Evaluation of the available data by both Parazzini et al8 and by Thom and Brown9 concluded that the evidence for an association between obstetrical trauma and urinary incontinence is “scanty and controversial.”
To address this issue, we conducted a survey of nulliparous, postmenopausal women with regard to the prevalence of urinary incontinence. The objective of this survey was to determine the prevalence of urinary incontinence symptoms in a nulliparous population, so as to evaluate the effect of aging without the effect of childbirth. Other risk factors for the development of urinary incontinence were also investigated.
A questionnaire was distributed to 190 nuns residing in two motherhouses in Rochester, New York. Data on age, race, weight, height, medications, and medical, surgical, and reproductive histories were obtained. Subjects were asked if they had a current problem with urine loss. Those with incontinence continued to answer questions related to the circumstances of urine loss and the quantity of leakage, as summarized in Table 1. In addition, they completed the Incontinence Impact Questionnaire.10 Univariate analyses and multivariate logistic regression were used to assess the effect of various factors on the likelihood of developing urinary incontinence.
Of 190 nuns who received the questionnaire, 149 (78.4%) completed it. Characteristics of this cohort are shown in Table 2.
All of the nuns were nulliparous, and all but one were white. The mean age (± standard error [SE]) of the group was 68 (±11.7), with a range of 39–91 years. The mean (±SE) body mass index (BMI) was 27.3 (±5.6).
Almost all (96.5%) were postmenopausal, and 40.4% had been on hormone replacement therapy (HRT) in the past. Almost half (n = 74) of this group of nulliparous nuns indicated a problem with urinary incontinence. This figure does not include five nuns who answered “no” to having a problem with bladder control, but “yes” to questions related to urine loss under stress conditions. Of those noting incontinence, 63% were slightly bothered by it, 25% were moderately bothered, and 4% were greatly bothered. For the vast majority (69%), the problem was ongoing for years. Among incontinent nuns, 52% were using sanitary pads to protect their clothing. When asked about the frequency of incontinence episodes, 10.3% leaked once a day, and 19.1% leaked several times a day.
Based on the symptom survey shown in Table 1, 22 nuns (29.7%) indicated pure stress incontinence, 18 (24.3%) indicated pure urge incontinence, and 26 (35.1%) indicated mixed incontinence. Included in the mixed incontinence group are those who answered “yes” to the majority of questions addressing both urge and stress conditions. Eight nuns (10.8%) had urine loss of unclear etiology. Of the nuns who reported that their urine loss was neither stress nor urge related, one nun leaked urine on long walks only, one had post-void dribbling, and one had overflow incontinence diagnosed by previous urodynamics.
Statistically significant univariate risk factors for urinary incontinence included BMI (P = .001), current HRT use, multiple urinary tract infections, hypertension, arthritis, depression, hysterectomy, and previous spinal surgery (all P < .05). Age, years after menopause, prior HRT, and diuretic use were not statistically different between the continent and incontinent groups (Table 2).
Table 2 also shows the result of multivariate logistic regression. Body mass index, multiple urinary tract infections, and depression remained statistically significant risk factors (P = .001, .033, and .022, respectively). Age was not a statistically significant independent risk factor for urinary incontinence.
The Incontinence Impact Questionnaire demonstrated that urinary incontinence limited activities outside the convent. Among incontinent nuns, 16 (21.9%) reported that their incontinence affected church attendance, 49 (66.2%) stated that urine leakage had an impact on their ability to go places in public, and 34 (46.0%) stated that it affected their sleep (Figure 1).
The prevalence of urinary incontinence in this nulliparous, predominantly postmenopausal population is well within the range reported in studies of community-dwelling, postmenopausal, predominantly parous women. The Heart and Estrogen/Progestin Replacement Study (HERS) Research Group reported a 56% rate of at least weekly incontinence.7 Brown et al11 reported a prevalence of 41% of incontinence in their group of “community-dwelling” women, who were at least 65 years.
We cannot conclude from comparison of our prevalence estimates in nulliparous women with those from studies of predominantly parous women that parity is not associated with incontinence. However, if parity and pelvic trauma are major risk factors for stress urinary incontinence,12 and if urge incontinence is the most common cause of urinary incontinence among the elderly,2 one might expect that the relative proportion of stress- and urge-related urinary incontinence to be different between parous and nulliparous postmenopausal women. Based on these assumptions about etiology, we would have anticipated finding a higher proportion of urge incontinence relative to stress urinary incontinence among our cohort of elderly nulliparous nuns, as compared with relative proportions among parous, post-menopausal women. Our findings did not support this expectation. Even in the absence of pelvic floor trauma from childbirth, urine loss among our sample of nuns is associated more with symptoms of stress urinary incontinence than with those of urge incontinence.
Severity of urinary incontinence can be measured by the amount of urine lost and by the frequency of incontinence episodes. Because the parameters used to quantify severity of incontinence varied so greatly in other prevalence studies, we could not draw any conclusion in comparison, except that there is a wide range in the severity of incontinence.
We found that BMI was strongly correlated with urinary incontinence, which confirms the findings of others.13 There was also more incontinence noted in women with multiple urinary tract infections, hypertension, arthritis, and hysterectomies, but this did not reach statistical significance when controlling for other factors. This lack of statistical significance might be due to our limited sample size. Advancing age was not an independent risk factor for having urinary incontinence in this predominately postmenopausal cohort. When stratified by decades, the percentage of reported urinary incontinence increased. However, this was not statistically significant.
Urinary incontinence has an impact on the individual's quality of life, ranging from reduced participation in social activities to psychosocial well-being, including depression, low self-esteem, shame, and guilt.14 Depression was significantly associated with urinary incontinence in our study group. These findings are consistent with prior studies.
Regarding quality of life, urinary incontinence had the most pronounced effect on activities outside the convent and on sleep.
In summary, our data show a surprisingly high prevalence of symptoms of urinary incontinence among post-menopausal, nulliparous nuns. Moreover, incontinence symptoms are sufficiently severe, in terms of frequency, duration, and amount, that quality of life is impaired in a number of dimensions. These findings appear to be contrary to the conventional wisdom that nulliparity protects against stress urinary incontinence.
To explore these descriptive results in a more rigorous manner, we are undertaking a study in which findings on physical examination and urodynamic results from nulliparous nuns will be compared with those of their parous biological sisters. Ongoing studies on the relationship between vaginal delivery and subsequent pelvic floor dysfunction will have important implications on matters ranging from policies regarding elective cesarean delivery to the direction of basic research on connective tissue in the pelvis and perineum.
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