Pelvic organ prolapse (prolapse) results in more than 200,000 surgical procedures annually in the United States1 and is the most common indication for hysterectomy in middle-aged women.2 Surgical procedures for prolapse account for direct costs of over $1 billion each year in the United States.2,3 Nearly 75% of women report a profound effect on quality of life associated with prolapse symptoms.4
The reported prevalence of prolapse varies considerably depending on the population studied and definition of prolapse. In population-based studies, 32–98% of middle-aged and older women are reported to have some degree of prolapse on examination.5–7 However, the stage of prolapse is not directly associated with prolapse-related symptoms,8–10 and only 4–10% of women report symptomatic prolapse.11,12 There are even fewer population-based studies estimating the prevalence of or degree of bother associated with symptomatic prolapse, and very limited data in racially diverse populations. Although previous studies using multivariable analyses have reported increasing age, weight, parity, and weight of largest infant delivered vaginally, ethnic origin, lower education, and vaginal trauma or episiotomy during labor to be risk factors for objective proplapse,6,7,10,12,13 there are fewer data on risk factors for symptomatic prolapse, particularly in a racially diverse, population-based cohort such as ours that includes detailed labor and delivery data.
Data ascertaining which women are most likely to be symptomatic and what symptoms they experience, are critical to better define and understand prolapse. We conducted this study to estimate the prevalence of and identify risk factors for symptomatic pelvic organ prolapse as well as level of bother in a racially diverse, population-based cohort of middle-aged and older women.
PARTICIPANTS AND METHODS
From October 1999 through February 2003, 2,109 community-dwelling women were enrolled in the Reproductive Risks for Incontinence Study at Kaiser, a population-based, racially diverse cohort of middle-aged and older women. The study population was constructed by identifying women between 40 and 69 years of age who, since age 18 years, had been members of the Kaiser Permanente Medical Care Program of Northern California, a large integrated health care delivery system with more than 3 million members that serves approximately 25% of the population in the area. Although previous studies have found Kaiser Permanente Medical Care Program of Northern California members to underrepresent extremes in economic status and to be slightly more educated, members have been shown to be very similar to the population in the geographic area served with respect to all other demographic characteristics.14 Eligibility included having at least one half of all births at Kaiser. Details of the Reproductive Risks for Incontinence Study at Kaiser have been reported previously.15
Data on symptomatic prolapse were ascertained by a self-report questionnaire. The questions were modified from those used in previous epidemiologic studies found to be the most specific and to have the highest positive predictive value for prolapse at or beyond the hymen on examination.11 Symptomatic pelvic organ prolapse was defined as affirmative answer to either: “During the past 12 months,…” 1.) “…have your pelvic organs (uterus, bladder, rectum) been dropping out of your vagina causing a feeling of bulging, pressure or protrusion? (This is sometimes called prolapse),” or 2.) “…has there been a visible bulging or protrusion from your vagina?” Women responding yes to either question were identified as having symptomatic prolapse and asked “How much does it bother you?” with response options of not at all, slightly, moderately, and greatly. Women with symptomatic prolapse also completed a supplemental questionnaire to ascertain prior prolapse surgery or treatment with a pessary, specific symptoms of prolapse, overall bother from these symptoms, and whether prolapse affected their ability to perform specific activities. To avoid misclassification that would interfere with risk factor analyses, women were excluded from the study if they had a history of prolapse, but did not have symptoms of prolapse within the last year (n=108).
Factors potentially associated with prolapse were assessed by questionnaire, interview, and medical record review, including questions on age, race or ethnicity, demographic characteristics, reproductive and menopause history, presence of selected medical conditions (for example history of irritable bowel syndrome and current constipation), prior pelvic and other surgeries (including hysterectomy, and pelvic organ prolapse repair), general health status now and compared with one year ago, and sexual function. Body mass index (BMI) was calculated (kg/m2) based on the participant's weight and height measured at the time of the interview. Method of delivery (vaginal or cesarean) and other delivery measures, such as birth weight and duration of second stage of labor, were abstracted from review of labor and delivery and surgical medical records archived since 1946. If method of delivery was not available from medical record review (8%), self-report was used.
Other pelvic floor disorders assessed by self-report were urinary incontinence and flatal or fecal incontinence, by frequency, in the past year. Women were defined as having these conditions if they reported weekly or greater urinary or flatal incontinence or monthly or greater fecal incontinence, because these frequencies have been observed as having substantial effect on daily activities.16,17
Prevalence of symptomatic prolapse is presented as percentage and 95% confidence interval (CI) of the women included in this study (N=2,001), weighted by the underlying Kaiser population. Women with symptomatic prolapse were compared with women without symptomatic prolapse. Univariable statistically significant differences were determined using a χ2 test for nominal variables and a test for trend for ordinal variables. Tests for trend were based on orthogonal linear contrasts in the log odds ratio across the ordinal categories.18 We used multivariable logistic regression models to control for potential confounding variables and to determine the independent associations between potential risk factors identified a priori and prolapse. Backwards elimination was then used to select the candidate variables with P<.2 after adjustment, a liberal criterion intended to minimize potential confounding. Age was included in all multivariable models on a priori grounds, whereas fecal and urinary incontinence were excluded a priori because they were considered to be part of the outcome and associated with pelvic floor dysfunction, rather than risk factors for prolapse. Results are presented as odds ratios and 95% confidence intervals. Values of P in multivariable models were based on tests for pair-wise comparisons for dichotomous variables, tests for heterogeneity for nominal variables, and tests for linear trend for ordinal variables. Tests of heterogeneity were from Wald (type III) χ2 test in logistic regression models. Pair-wise comparisons were also made using Wald χ2 tests. Multivariable logistic regression models were used to measure the independent association of symptoms with activities affected by prolapse. All analyses were carried out in SAS 9.1 (SAS Institute, Cary, NC). This study was approved by the institutional review boards of the University of California, San Francisco and the Kaiser Foundation Research Institute.
The mean (±standard deviation) age (N=2,001) was 55.6±8.6 years, and participants were racially diverse (47% white, 19% African-American, 17% Latina, and 17% Asian).15 One hundred eighteen women reported symptoms of prolapse in the previous 12 months, for a prevalence of 5.7% (95% CI 4.8–6.8). Among these 118 women, more women reported a feeling of bulging, pressure or protrusion from the vagina (n=109; 92%) compared with visible bulging or protrusion from the vagina (n=57; 48%), and 48 (41%) reported both symptoms. Almost 50% of these women reported moderate or great distress, and 35% reported that the symptoms affected at least one physical, social, or sexual activity. Nine percent of symptomatic women had previously undergone prolapse surgery, and 12% had used a pessary for prolapse treatment, with one half reporting associated moderate or great improvement of their prolapse symptoms.
In univariable analyses of factors potentially associated with symptomatic prolapse in the past year, symptomatic prolapse varies by race or ethnicity, from 3% of African-American women to 9% of Latina women (P=.04; Table 1). Symptomatic prolapse was one half as prevalent among African-American compared with white women. Vaginal delivery was strongly and significantly associated with symptomatic prolapse, increasing with the number of deliveries. Women with only cesarean deliveries had a similar risk of prolapse as nulliparous women.
Fair or poor self-perceived health status was strongly associated with higher prevalence of symptomatic prolapse, as was worsened health status today compared with health status 1 year ago (Table 1). Additional significant univariable risk factors for symptomatic prolapse include constipation and irritable bowel syndrome, urinary tract infection within the last year, hysterectomy, and current estrogen use.
Prolapse was also significantly associated with other pelvic floor disorders. Compared with women without the disorder, the odds of symptomatic prolapse was 2.5 times greater among women with at least weekly urinary or monthly fecal incontinence (Table 1).
In the multivariable model, factors independently and significantly associated with symptomatic prolapse were health status (2.3-fold increase in odds of reporting poor or fair health), constipation (2.5-fold increase), and irritable bowel syndrome (2.8-fold increase; Table 2). In addition, one or more vaginal deliveries was associated with a 3- to 5-fold higher odds of having symptomatic prolapse compared with women with no vaginal deliveries. Symptomatic prolapse was significantly less common among African-American women than among white women, with an odds ratio of 0.4 (95% CI 0.2–0.8). Age, education, BMI, diabetes, hysterectomy, and estrogen use were not independently associated with reporting symptomatic prolapse in the past year.
We also examined the association of symptomatic prolapse and intrapartum characteristics in the subset of parous women (n=1,615). In univariable analysis, compared with women without symptomatic prolapse, women with symptomatic prolapse were more likely to have at least one neonate weighing 4,000 g or more (OR 1.9, 95% CI 1.3–3.0) or three or more vaginal deliveries (OR 1.9, 95% CI 1.0–3.4), compared with women with one vaginal birth. Age at first delivery, years since first birth, years since last birth, induced labor, epidural anesthesia during labor, length of second stage, episiotomy, and vaginal tearing were not significantly associated with symptomatic prolapse (data not shown). In a multivariable analysis, giving birth to at least one child weighing more than 4,000 g was independently associated symptomatic prolapse (OR 1.9, 95% CI 1.2–3.0).
Among the 118 women reporting prolapse symptoms, 47% (n=55) reported moderate or great bother associated with prolapse. One hundred five (89%) women completed questions on symptom bother on the prolapse supplemental questionnaire. One quarter to one half of women reported experiencing specific prolapse-related symptoms of pelvic pressure, pelvic, lower abdominal or low back pain, vaginal irritation, or a bulge form the vagina in the past year (Table 3). The proportion of women reporting each symptom, by type, was similar between women who reported a feeling of bulging, pressure, or protrusion and those with a visible bulge from the vagina (results not reported). Symptoms of pelvic pressure and bulging were most bothersome, while needing to push vagina to help urinate was the least bothersome prolapse symptom. Prolapse adversely affected any activity for 35% of women (Table 3). Nearly one quarter of women reported an adverse effect of prolapse on brisk walking and strenuous exercise. The only significant associations between specific symptoms and activities were for low back pain associated with physical activity (P=.004) and vaginal irritation associated with sexual activity (P=.003).
Symptomatic prolapse was associated with sexual dysfunction in univariable analysis. Women who reported a lack of sexual interest, inability to relax and enjoy sexual activity, or difficulty in having an orgasm as being somewhat or very much a problem were twice as likely to have symptomatic prolapse compared with women who reported these sexual problems as being a little bit of a problem or not a problem (P<.05 for all comparisons). However, when controlling for ethnicity, general health status, parity, irritable bowel syndrome, constipation, fecal incontinence, and urinary incontinence in multivariable analyses, symptomatic prolapse did not predict sexual dysfunction (data not shown).
In this racially diverse population-based cohort of middle-aged and older women, 6% of women reported symptoms of pelvic prolapse in the last year. The prevalence of symptomatic prolapse observed in our study is similar to that reported in population-based studies in Sweden (8%) and in the United States (4%).11,12
Although the literature indicates that objectively detectable prolapse is common and observed in 30–98% of women depending on the age of study participants,6,7,10 the clinical relevance of these findings and the effect of prolapse on women is less clear. Several studies have observed that the threshold for symptomatic prolapse, most often reported as “bulging,” occurs when the leading edge of the prolapse on examination is at or beyond the hymen.8,9,11 Among women with stage II prolapse by the pelvic organ prolapse quantification (POP-Q)19 system, the prevalence of self-reported bulging symptoms ranges from 57% with the leading edge of the prolapse 1 cm above the hymen (–1) to 87% with the leading edge 1 cm below the hymen (+1).8 In studies with both objective and subjective assessment of prolapse, the correlation between the degree of prolapse, usually measured by POP-Q, and the presence of symptoms is not linear.8–10,20 Symptoms are common in stage 3 and 4, and uncommon in stage 1 prolapse. Women with stage 2 prolapse, however, report a wide range of symptoms.8,9 Even though it is well defined anatomically, the range of symptoms within the stage is wide; hence, decisions about treatment for patients cannot be guided by staging alone. In our study, we confirm that women with symptomatic prolapse ascribe many symptoms to the prolapse, and as many as one third of the symptomatic women reported that their activity was restrained in some way. However, the study was not designed with a control group to validate the symptoms.
Most studies to date have not addressed the association of race or ethnicity and prolapse. After adjusting for common risk factors using multivariable analyses, we observed that African-American women were significantly less likely to report symptomatic prolapse compared with white women (OR 0.4, 95% CI 0.2–0.8). A similar association of African-American race being a protective factor for anatomic prolapse was observed in the Women's Health Initiative trials, which also included a racially diverse population.6 There is evidence for anatomic and physiologic variation in the pelvic floor that may affect risk of pelvic organ prolapse.21,22 For example, African-American women may have increased strength and pelvic muscle mass compared with white women.23 Other possible explanations for racial disparity in rates may include cultural attitudes toward symptomatology of pelvic organ prolapse. An analogous relationship between race or ethnicity and urinary incontinence has been reported.15,24 Although the cause of the differences in prevalence of prolapse and urinary incontinence between racial and ethnic groups has not been identified, physiological, behavioral, and reporting differences have been suggested as explanations.15,23,25
In the current study, vaginal parity was associated with symptomatic prolapse, which increased three-fold with one to five-fold with three or more vaginal deliveries (P=.001 for trend; Table 2). This is consistent with results from other population based studies.6,7,12,13 Similar to other studies that included mode of delivery, we did not observe any increased risk of symptomatic prolapse with only cesarean delivery, suggesting that delivery method, rather than pregnancy, contributes to developing symptomatic prolapse.7,13 Because the Reproductive Risks for Incontinence Study at Kaiser collected detailed parturition data, we included many parturition variables in our analyses of risk factors for prolapse. We found no significant associations except for route of delivery and giving birth to a large infant. Larger studies should be performed to better assess the association of pregnancy and delivery, by method, with pelvic organ prolapse.
In our study, constipation and a history of irritable bowel syndrome were strong and independent risk factors for symptomatic prolapse. This association of constipation and prolapse has not been observed in other studies that included the condition as a potential risk factor for prolapse.6,10 Straining with chronic constipation may damage the pelvic floor; however, constipation may be a symptom of posterior prolapse as well. It is also possible that women with other abdominal symptoms are more aware of any abdominal and pelvic symptoms. The cross-sectional design of the study does not allow any inference about causal relationships in this matter.
Age and body mass index, which are well-documented risk factors for urinary and fecal incontinence, were not risk factors for symptomatic prolapse in this study. Prior studies have had inconsistent findings of the age–prolapse association.6,7,12 It is possible that older women are less aware of prolapse symptoms or may be engaged in fewer activities that would provoke prolapse symptoms compared with younger women. Although body mass index has not been identified as a significant independent risk factor for prolapse in most previous studies,5,7,12,13 one large survey found increasing body mass index to be associated with clinically diagnosed prolapse.6 Waist circumference has been reported as a risk factor for prolapse, suggesting that central obesity may be associated with the prolapse mechanisms.5,6 These differences in identified risk factors for prolapse are not understood and may reflect differences in populations studied and definitions of prolapse.
There are minimal data on sexual function in women with prolapse who have not had prolapse surgery. One study reported significantly lower scores on sexual function measures in women with prolapse as compared with women without prolapse.26 In our study, when controlling for confounders, we did not find that symptoms for prolapse predicted sexual dysfunction.
We consider urinary, fecal, and flatal incontinence part of a syndrome of pelvic floor dysfunction together with prolapse, rather than causally associated with prolapse. Indeed, prolapse and urinary and fecal incontinence likely share causative factors, including damage to the pelvic floor as a result of pregnancy and child birth.27,28 In fact, we observe that some risk factors for urinary incontinence are risk factors for prolapse as well, such as ethnic origin and delivery type. Irritable bowel syndrome is a risk factor for both fecal incontinence and prolapse, although not for urinary incontinence. Therefore, prolapse and urinary and fecal incontinence may be markers for pelvic floor damage and dysfunction. This underscores the importance of asking patients with either prolapse or fecal or urinary incontinence whether they experience symptoms of the other conditions.
Our study had several limitations that should be considered when interpreting the results. The study was cross-sectional and thus cannot determine causal associations. The participants were middle-aged and older community-dwelling volunteers with long-term enrollment in a pre-paid health delivery system with generally equal access to care. Therefore, these results may not be generalizable to younger or older women, or those without insurance. Even though the survey sample is population-based, women with very high or very low income were underrepresented. In multivariable analyses, education was not independently associated with symptomatic prolapse. Because education may be viewed as a proxy variable for socioeconomic status, this indicates that the selection bias related to income does not have substantial influence on the results.
Pair-wise comparisons were only reported if the overall test for heterogeneity was statistically significant, following the principals of Fisher's least significant difference. A possible limitation of this study is that we did not inflate the P values using a Bonferroni correction. However, most of the statistically significant differences in Tables 1 and 2 would have survived this correction. Vaginal delivery compared with nulliparous women is the only pair-wise comparison that may become nonsignificant. However, this result would not have affected the statistically significant linear trend.
Symptomatic prolapse was defined by self-report without confirmation by examination. The sensitivity and specificity of the screening questions to identify symptomatic prolapse are unknown and misclassification of subjects may indeed have happened. Unfortunately, there are as yet no standardized definitions or instruments to determine clinically significant prolapse. Pelvic organ prolapse remains an ill-defined condition. Clinically, the presence and severity of prolapse are described using a combination of clinical staging and the patient's history, including bother and effect on quality of life. For research, the prevalence of pelvic organ prolapse symptoms and validity of instruments to identify and quantify pelvic organ prolapse symptoms must be further investigated and related to clinical signs of prolapse.
Symptomatic pelvic organ prolapse was reported in 6% of middle-aged and older women, and almost one half of women reported that the prolapse symptoms caused moderate to great bother. Women most at risk for symptomatic prolapse were those reporting poor health status, constipation, and irritable bowel syndrome. In addition, one or more vaginal deliveries was associated with a three- to five-fold higher odds of having symptomatic prolapse. The risk of symptomatic prolapse was significantly lower among African-American women than among white women.
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