Stress urinary incontinence (SUI) and pelvic organ prolapse (POP) are highly prevalent conditions1 that often are managed surgically. Since the introduction of the tension-free mesh slings in the late 1990s for incontinence2 and the subsequent development of vaginal mesh procedures for POP,3 the surgical management of both conditions has increased substantially.4,5
With these recent changes in surgical practice, an assessment of the lifetime risk of surgery for SUI and POP is necessary to understand the overall public health effect and burden of pelvic floor disorders. Furthermore, lifetime surgical risk has critical implications regarding the morbidity associated with surgery,6,7 the need for skilled surgeons, and the importance of training future health care providers. Given that urinary incontinence and POP are more common in the elderly population1 and that the U.S. population is aging,8 a contemporary assessment of lifetime surgical risk is necessary for accurate projections regarding health care use in the coming decades.9,10
A commonly referenced statistic is that a woman has an 11.1% lifetime risk of surgery for either incontinence or POP by the age of 80 years.11,12 This estimate was based on 384 patients who underwent surgery in the northwest region of the United States in 1995. The small number of study patients, limited geographic region, and results from two decades ago potentially limit the applicability of the findings to current surgical practice.
Given the limitations of prior data regarding the lifetime risk of urogynecologic surgery in the United States, we sought to use a large, population-based cohort to evaluate the age-specific incidence of surgery for SUI, POP surgery, and either SUI or POP surgery and to estimate the cumulative risk of surgery over a woman's lifetime.
MATERIALS AND METHODS
For this analysis, we used 10 years of data (2002–2011) from the MarketScan Commercial Claims and Encounters database and Medicare Supplemental and Coordination of Benefits database (© 2012 Truven Health Analytics; all rights reserved).13,14 These population-based data included deidentified, adjudicated, health care claims from approximately 150 payers in the United States. Individuals included in these databases were those with commercial, employment-based insurance such as employees, their spouses, dependents as well as retirees. Claims and enrollment data were validated by Truven Health Analytics to ensure completeness, accuracy, and reliability. Unique individuals can be followed over time using encrypted identification numbers, and detailed enrollment data ensured that only those individuals who could generate a claim were included in the population at risk at any given time. This database included approximately 53 million individuals in 2011. Of note, in 2011, 55.1% of the U.S. population, or 170.1 million individuals, had employment-based insurance; thus, this database includes a significant proportion of those with employer-based insurance.15 This study was determined to be exempt from further review by the institutional review board at the University of North Carolina at Chapel Hill because the database contained only deidentified data.
On January 1 of each year from 2007 to 2011, we identified all women aged 18–89 years who were continuously enrolled for the prior 3 years (look-back period) and the next 12 months (follow-up period). We excluded women aged older than 89 years because the number of women and procedures in this age category were low; thus, the data were not very precise for this age group. We also excluded women who had any surgery for SUI or POP during the 3-year look-back period based on Current Procedural Terminology (CPT) codes. For SUI, we included the following CPT codes: 57288; 51840, 51841, 58152, 51715, 57220, 51845, 57289, 51990, 51992, 58267, or 58293. For POP, we included the following CPT codes: 57200, 57210, 57230, 57240, 57250, 57260, 57265, 57268, 57270, 56810, 57284, 57285, 57423, 57267, 57282, 57283, 57280, 57425, 57106, 57107, 57109, 57110, 57111, 57112, 57120, or 58400. We also included hysterectomy as a POP surgery if there was a primary diagnosis of prolapse associated with the hysterectomy, which occurred on the same date as surgery. A diagnosis of POP was based on the International Classification of Diseases, 9th Revision, Clinical Modification diagnosis code of 618.x.
Among women who had no SUI or POP surgeries during the look-back period, we identified all incident surgical procedures for SUI and POP during the 12-month follow-up period. We estimated the number of women who underwent a surgery for SUI, the number with a surgery for POP, and the number of women with any surgery for either SUI or prolapse during the 12-month follow-up period. In this open cohort study, a woman could contribute more than 1 year of age-specific follow-up if she remained eligible on January 1 of subsequent years.
We estimated age-specific, 1-year risks of incident surgery by dividing the number of women experiencing a surgery during the 12 months of follow-up by the number of eligible women for each year of age from 18 to 89 years. We also estimated the average risk for the following age groups: 18–29, 30–39, 40–49, 50–59, 60–69, 70–79, and 80–89 years to facilitate comparison with previously published estimates.11,12 We estimated age-specific surgery rates for SUI only, POP only, and either SUI or POP and reported annual risk per 1,000 women with 95% confidence intervals (CIs) based on the binomial distribution.16
Our primary outcome was the cumulative risk of undergoing either SUI or POP surgery beginning at the age of 18 years up to 80 years of age. Because our objective was to estimate lifetime risk of these surgeries, it was important to account for death as a competing risk, because not all women live to the age of 80 years. Age-specific estimates of all-cause mortality were calculated using national census data and mortality data from the Centers for Disease Control and Prevention on U.S. females from 2007.17,18 We used the DevCan software (National Cancer Institute)16 to estimate the cumulative risk of surgery for SUI, POP, or either with appropriate 95% CIs adjusted for the competing risk of death using methods developed by Fay et al.19,20
For our primary analysis, the identification of incident surgeries during the follow-up period was based on excluding women who had any history of surgery for either SUI or POP during the prior 3 years. To assess the sensitivity of our findings, we repeated the analysis using a 5-year look-back period, limiting the population of eligible women to those who had 5 years of continuous enrollment and no SUI or POP procedures during that period. Although the longer look-back period increased the likelihood that the surgeries identified during follow-up were truly incident (rather than repeat) procedures, the tradeoff was that fewer women have 5 years of continuous enrollment, and thus, our age-specific estimates and ultimately the estimates of lifetime risk based on these data were less precise.
From 2007 to 2011, 10,177,480 women 18–89 years of age contributed an average of 2.5 years of follow-up for a total of 24,979,447 person-years of follow-up (Table 1). Among these adult women, there were 65,397 women who had an incident surgery for SUI, 57,755 women who had an incident surgery for POP, and 94,518 women who had an incident procedure for either SUI or prolapse.
The age-specific estimates of the 1-year risk of incident surgery for SUI only, POP only, or either incontinence or prolapse for women between the ages of 18 and 89 years are shown in Figure 1. For each decade of age, we also estimated the average annual risk (Table 2). Because Figure 1 illustrates the 1-year risk of incident surgery for each year of age between 18 and 89 years, it provides more granularity than the data in Table 2. For SUI, there were two peaks: first at age 46 years when the annual risk was 3.8 per 1,000 women and then at age 70–71 years when the annual risk was 3.9 per 1,000 women. For POP, the annual risk increased with age until a peak of 4.3 per 1,000 women at age 71 and 73 years. For either incontinence or prolapse surgery, the highest risk was 6.0 per 1,000 women at age 70 years.
For the primary outcome, we estimated that the lifetime risk for either incontinence or prolapse surgery was 200.1 per 1,000 women or 20.0% (95% CI 19.9–20.2) from age 18 to 80 years (Fig. 2). For surgery for SUI or POP surgery, the lifetime risks were 13.6% (95% CI 13.5–13.7) and 12.6% (95% CI 12.4–12.7), respectively. The previously reported estimate of an 11.1% lifetime risk of either surgery11 is now reached by the age of 58 years based on the annual risk of surgery during 2007–2011.
We conducted several sensitivity analyses to determine the robustness of our findings. In the sensitivity analysis using a 5-year (rather than 3-year) look-back period, the lifetime risks were slightly lower at 19.8% (95% CI 19.6–20.0) for either surgery, 13.5 (95% CI 13.3–13.7) for SUI, and 12.4% (95% CI 12.2–12.6) for POP surgery. We also conducted a sensitivity analysis in which we did not consider hysterectomy with a primary diagnosis of POP as a qualifying prolapse procedure. The resulting estimates of lifetime risk of surgery for POP were slightly lower (11.8%, 95% CI 11.7–11.9) as were those for the combined risk of surgery for either POP or SUI (19.5%, 95% CI 19.3–19.6). We also considered whether regional variation in surgical rates would affect our estimates. Weighting the Marketscan sample to more accurately reflect the geographic distribution of women with employer-based insurance in the United States resulted in estimates of lifetime risk of surgery for SUI or POP that were slightly lower (19.4%).
In this contemporary, population-based analysis, we found that the lifetime risk of surgery for either SUI or POP was 20.0%. Thus, in a hypothetical cohort of women who are currently 18 years of age, one of every five would be expected to undergo surgery for either SUI or POP by age 80 years, highlighting the public health effect of these conditions. For perspective, a woman's lifetime risk of developing breast cancer is 14.8%, whereas the lifetime risk of lung cancer is 6.3%.21 Despite the fact that the lifetime risk of SUI and POP surgery is significantly higher than that of breast cancer or lung cancer, women lack awareness and knowledge regarding these gynecologic conditions,22,23 which translates into limited health care-seeking for these conditions, which greatly impair quality of life.22,24
Our cumulative incidence of 20.0% is nearly double that of two older U.S studies, which reported rates of incontinence and prolapse surgery of 11.1%11 and 11.8%.12 We believe that this may be attributable to several different factors. First, the introduction of new surgical techniques, namely midurethral synthetic slings and transvaginal mesh procedures for POP, have resulted in higher rates of SUI 4 and mesh prolapse surgeries.5 For example, the rate of sling procedures increased from 209.7 to 266.5 per 100,000 person-years from 2000 to 20094 and the rate of vaginal mesh procedures increased from a rate of 36.7 to 60.8 per 100,000 person-years from 2005 to 2010.5 These products potentially allowed more gynecologists to offer pelvic floor repair based on a perception of improved ease and efficiency. In addition, the regional variation in SUI and POP surgery in the United States may contribute with higher rates in the South and the Midwest compared with the Northeast and West.4,5 Both of the prior studies were based in the Northwest,11,12 which may have underestimated the overall lifetime risk of surgery. Finally, previous investigations did not report CIs around the cumulative risk, and with significantly smaller sample sizes, these estimates were likely less precise.
Estimated lifetime incidence rates of pelvic floor surgeries in other countries vary. In The Netherlands, de Boer et al25 reported a 20.3% risk of prior surgery in women aged 76–85 years. Among parous women in the United Kingdom, Abdel-Fattah et al26 found a 12.2% lifetime risk of incontinence and POP surgery. A cross-sectional study from Australia reported a rate of 19% for POP surgery, which is significantly higher than our rate of 12.6%.27 This international variance could be explained by true global differences in disease prevalence or differences in surgical practice patterns. For accurate public health planning, it is helpful to have current estimates of surgical rates that are reflective of national practice.
Regarding age-specific incidence, our study showed similar trends to prior studies with the highest rates of surgery in women aged 70–79 years.11,12 Our annual risk of surgery for either incontinence or POP surgery in this age group was 5.3 per 1,000 women (95% CI 5.2–5.4) compared with 3.70 per 1,000 person-years from Fialkow et al12 and 6.62 per 1,000 person-years from Olsen et al.11 By evaluating incident surgery rates by age in decades, some of the details regarding the effect of age may not be evident. In our study, we were able to provide insight into how SUI surgery rates change with yearly increases in age, and we found two peaks in incidence around age 46 and 70–71 years. For POP, we found that our highest annual risk of incident surgery was 4.3 per 1,000 women at 71 and 73 years, and Smith et al27 also noted the highest rate among 65–69 year olds from 2001–2005 with a rate of 5.0 per 1,000 person-years (95% CI 4.7–5.4).
The strengths of this study include the large, population-based cohort of more than 10 million women that reflects practice patterns across the entire country during recent years. This is in contrast to prior U.S. studies that used data from almost two decades ago, focused on a single region, evaluated substantially smaller cohorts, and did not estimate CIs. Our estimates of lifetime risk are based on the surgery rates between 2007 and 2011, which reflect practice since the introduction of mesh procedures for incontinence and POP.4,5 The magnitude of data allowed for calculation of incidence rates at every year of age, permitting a more accurate estimation of cumulative incidence. We also estimated CIs to provide a sense of the precision of our age-specific and cumulative incidence estimates. Lastly, a novel aspect of our study is that we accounted for competing risks of mortality, and we used rigorous, state-of-the-art methodology developed and used by the National Cancer Institute to estimate lifetime risk of different types of cancer.16,19,20
Our study also had several limitations. Although health care claims data provide an enormous number of patients and procedures to evaluate, they do not permit a review of past medical records, and we are limited to the data included in health care claims. For example, we were unable to evaluate race, body mass index, and comorbidities such as obesity, diabetes, or smoking with accuracy. Furthermore, we were limited our ability to definitively exclude women with prior surgeries; however, our estimates did not change significantly when we conducted a sensitivity analysis with a longer look-back period. For POP surgeries, we included hysterectomies with a primary diagnosis of prolapse. It is possible that uterine prolapse may be used as a billable diagnosis to perform a hysterectomy for a nonbillable reason such as contraception and, thus, might result in an overestimation of the use of hysterectomy for symptomatic prolapse. These procedures represented 6.4% of incident procedures for POP and excluding them from the analysis had a modest effect on the estimates of lifetime risk. Our rationale for including hysterectomies was that women with uterovaginal prolapse are commonly undertreated by a hysterectomy alone because they do not undergo any concomitant prolapse surgeries. A study of California discharge data found that only 35% of women who underwent a hysterectomy for a primary diagnosis of uterovaginal prolapse had a concomitant apical support procedure.28 Our study population was comprised of individuals with employer-based insurance or those with supplemental insurance from their employer or retirement benefit once they transition into Medicare. We were not able to evaluate the uninsured or those on Medicaid, a population who may have different surgery rates. That said, the majority of Americans (55%) have employment-based insurance so these estimates represent a substantial portion of the U.S. population.15
Based on surgery rates from 2007 to 2011, the lifetime risk of undergoing SUI or POP surgery by the age of 80 years is 20.0%. These surgeries will place a growing demand on health care resources and will require a commensurate increase in the number of trained pelvic floor surgeons. The high rates of surgery for both SUI and POP continue to expose the need for improved prevention strategies.
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© 2014 by The American College of Obstetricians and Gynecologists.
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