Objective
The objective of the study was to determine the prevalence and identify potential risk factors for monthly fecal incontinence (FI) in women presenting for stress urinary incontinence (UI) surgery.

Study Design
From 655 women enrolled in the Stress Incontinence Surgical Treatment Efficacy Trial, baseline data were analyzed. FI was defined as occurring at least monthly. Independent variables included sociodemographics, health status and history, physical examination, and validated UI questionnaires. Multivariable logistic regression models compared women with FI with women with only UI.

Results
Prevalence of monthly FI was 16%, 10% for liquid stool, and 6% for solid stool. In multivariable analysis, increased risk of FI was associated (odds ratio, 95% confidence interval) with decreased anal sphincter contraction (4.5, 2.0 to 10.4), perimenopausal status (2.4, 1.1 to 5.0), prior incontinence surgery/treatment (1.8, 1.1 to 2.9), and increased UI bother (1.1, 1.1 to 1.2).

Conclusion
Women enrolled in a stress UI surgical trial have high rates of monthly FI and further evaluation of FI symptoms may be warranted.

Key words: fecal incontinence; risk factors; stress urinary incontinence

Fecal incontinence can be a devastating and socially isolating illness. Fecal incontinence affects 3-7% of women at least monthly and up to 24% of women within the last year. Women with dual incontinence (both urinary and fecal incontinence) have significant impairment in their quality of life. Rates of dual incontinence are higher than isolated fecal incontinence, ranging from 9% to 24%, depending on the clinical setting and the definition of fecal incontinence, which often includes incontinence to flatus.

Among women, risk factors related to fecal incontinence in both population-based and clinical studies include age, coexistence of urinary incontinence, high body mass index (BMI), hysterectomy, postmenopausal status, obstetrical history (parity and type of delivery), pelvic organ prolapse, and comorbid diseases. However, it is not apparent which type of urinary incontinence is more likely to be associated with fecal incontinence. Moreover, stress urinary incontinence (SUI) and urge urinary incontinence (UUI) may be associated with fecal incontinence through different mechanisms. The etiology of fecal incontinence remains multifactorial and treatment depends on the underlying mechanisms.

The Stress Incontinence Surgical Treatment Efficacy Trial (SISTEr), a randomized trial of autologous rectus fascial pubovaginal sling vs Burch colpopexy in women with SUI, afforded the opportunity to assess the prevalence of fecal incontinence in a women who participated in this study. Potential risk factors were also examined.

Design
The SISTEr enrolled 655 women who were randomized to 1 of 2 commonly performed surgeries for SUI. The trial design including inclusion and exclusion criteria are described in detail elsewhere. Women were eligible for randomization if they had predominant SUI symptoms in comparison with UUI symptoms. Women were diagnosed with predominant SUI by a combination of self-reported symptoms and clinical measures. Self-reported measures included 3 or more months of stress-type symptoms, mean micturition less than 12 times per day, and Medical, Epidemiologic, and Social Aspects of Aging Project (MESA) stress symptom score that was greater than the MESA urge symptom score. Clinical measures included observed leakage during a provocative stress test (bladder volume 300 mL or less), a maximal cystometric capacity of 200 mL or more, normal postvoid residual volume adjusted for pelvic organ prolapse stage (Pelvic Organ Prolapse Quantification System [POP-Q]), and unobstructed voiding on uroflow studies. All participants provided written informed consent, and each local institutional review board reviewed and approved the study protocol.

Measures
Data on fecal incontinence were collected at baseline (prior to randomization) by self-reported questionnaires. The occurrence of fecal incontinence was determined by the following questions: “Do you have leaking or loss of control of liquid stool?” and “Do you have leaking or loss of control of solid stool?” Frequency of leakage was ascertained with the question, “How often does this happen: less than once a month, more than once a month but less than once a week, more than once a month, but less than every day, or every day?” In this study, we report on fecal incontinence that occurred at least “more than once a month but less than once a week,” “more than once a week but less than every day,” and “every day.” Women who reported only liquid fecal incontinence were compared with women with solid fecal incontinence. Women in the solid fecal incontinence group have the combination of solid and liquid stool incontinence or isolated solid stool incontinence. These 2 groups were combined because of the low number of women who reported having isolated solid stool incontinence. The presence of flatal incontinence was assessed by the question, “Do you have leaking or loss of control of gas?” Frequency of flatal incontinence was assessed similar to fecal incontinence.

Factors potentially associated with fecal incontinence were assessed by questionnaires, physical examination, and urodynamic studies. Sociodemographic factors were ascertained through self-report and included age, race/ethnicity, education, and socioeconomic status. Socioeconomic status was measured with the Nam-Powers-Boyd Occupations Status Score that ranks occupations based on educational requirements and expected salary, in which a higher score indicates greater status. Self-reported health status and history factors included smoking status, presence of diabetes, and the frequency of straining with bowel movements. BMI (recorded in kilograms per square meter) was calculated from measured height and weight. Specific factors related to obstetrical and gynecological history included the number of vaginal deliveries, the weight of the largest baby, hysterectomy, and prior urinary incontinence surgery or treatment.

Prior urinary incontinence surgery included anterior repair, collagen injection, open or laparoscopic Burch colposuspension, Marshall-Marchetti-Krantz bladder suspension, needle bladder suspension (Raz, Pereyra, Gittes), and prior sling procedures. Prior urinary incontinence medical treatment included drug treatments, bladder training (including changes in fluid intake and timing of urination), pelvic muscle exercises, electrical stimulation, electromagnetic therapy, acupuncture, and biofeedback.

Menopause was defined as not having had a menstrual period for the past 12 months. Women self-reported their menopause status as “premenopausal,” “postmenopausal,” “somewhere in between,” and “not sure.” Women who reported being “somewhere in between” were classified as being perimenopausal.

Urinary incontinence symptoms were measured with the MESA, with higher scores indicating more frequent symptoms for each incontinence subscale (SUI and UUI). Physical examination factors included digital evaluation of anal sphincter contraction (normal or decreased), presence and stage of pelvic organ prolapse (POP-Q), and digital palpation of pelvic floor squeeze duration and strength (Brink score).

Urinary incontinence severity measures were used from 3 different sources combining both self-report and objective measures. Average number per day of incontinence episodes was collected by 3-day bladder diary. Objective measures included a 24-hour pad test (weight in grams) and urodynamic evaluation. Urodynamic severity measures consisted of maximum cystometric capacity (MCC), presence of detrusor overactivity, and intravesical Valsalva leak point pressure (VLPP) obtained during filling cystometry. The urodynamics protocol complied with the standards set forth by the International Continence Society including technical practice and standardized terminology. Details of the urodynamic protocol and interpretation guidelines have been previously reported.

Symptom bother was measured by the Urogenital Distress Inventory (UDI) to assess the degree to which urinary incontinence symptoms are troubling to women. Bother was computed as the average of the bother of the symptoms experienced,with subscales used to evaluate obstructive, irritative, and stress voiding symptoms. The Incontinence Impact Questionnaire (IIQ) was used to assess quality of life. Scores on the IIQ are reported as being in less than the 75th percentile or greater or equal to the 75th percentile of all reported scores. The Pelvic floor and Incontinence Sexual Impact Questionnaire (PISQ) measured the impact of urinary incontinence on sexual function, in which lower scores indicate better sexual function.

Data analysis
X2 testing and 1-way analysis of variance were used for categorical and continuous variables, respectively, to evaluate bivariate associations in women with only urinary incontinence, isolated liquid stool fecal incontinence, and solid stool fecal incontinence. A significance level of P

< .05 was used. For the multiple logistic regression analysis, monthly fecal incontinence (including both liquid and solid stool incontinence) was the dependent variable. The regression model utilized only the variables that were significant at the bivariate level. The final multivariable analysis included the 612 women with complete data for monthly fecal incontinence with the following exclusions: unknown menopausal status (n = 30) and incomplete UDI scores (n = 4), and missing data on detrusor overactivity (n = 10). One woman had both an unknown menopausal status and missing data on detrusor overactivity. All analyses were computed using SAS statistical software (SAS Institute, Inc, Cary, NC).

Results
Responses to questions on fecal incontinence were available from all 655 women who enrolled in SISTEr. The baseline prevalence of having both urinary incontinence and monthly fecal incontinence was 16% (n = 102), with 10% (n = 64) reporting loss of isolated liquid stool and 6% (n = 38) reporting solid fecal incontinence.

Variables that demonstrated a significant association with fecal incontinence in women are shown in Table 1. Women with either type of monthly fecal incontinence were slightly older, had higher BMI, were more likely to be use hormonal therapy, and be either peri- or postmenopausal than those women with only urinary incontinence. Fecal incontinent women had more flatal incontinence and a decreased sphincter contraction on physical examination. Women with fecal incontinence had a statistically significant difference in the duration of their pelvic muscle contraction. More women with either type of fecal incontinence had no ability to contract their pelvic muscles and fewer women with solid fecal incontinence (73%) could contract the pelvic floor muscles longer than 3 seconds when compared with women with only urinary incontinence (85%) or isolated liquid fecal incontinence (85%). No differences were seen with regard to racial/ethnic differences, educational level, or socioeconomic level.

In contrast to women with only urinary incontinence, women with either type of monthly fecal incontinence were more likely to have had prior urinary incontinence surgery and had higher scores of both stress and urge symptoms on the MESA. On the UDI, women with either type of fecal incontinence had higher total scores as well as higher scores for the obstructive symptoms and the irritative symptom score but not the stress symptom score. Women with either type of fecal incontinence had more impact on quality of life as with significantly different scores on the IIQ and the PISQ in comparison with women with only urinary incontinence. Women with solid fecal incontinence in comparison with women with isolated liquid fecal incontinence had higher IIQ scores, suggesting more impact on their daily activities.

In multivariable analysis, women had the greatest risk (odds ratio [OR], 95% confidence interval) of having monthly fecal incontinence if decreased anal sphincter contraction was found on digital rectal examination (OR 4.5, 2.0 to 10.4). Women who self-reported being perimenopausal (OR 2.4, 1.1 to 5.0) were at risk for fecal incontinence in comparison with women who were premenopausal. Prior urinary incontinence treatment or surgery (OR 1.8, 1.1 to 2.9) and increased symptom bother on the total UDI score (OR 1.1, 1.1 to 1.2) were marginally associated with increased fecal incontinence. The presence of detrusor overactivity (OR 0.3, 0.1 to 0.8) may be a protective factor for fecal incontinence.

Comment

A major finding of our study was that monthly fecal incontinence (including liquid and/or solid stool) affects 1 of 6 (16%) women undergoing surgery for stress incontinence as part of a select sample of women participating in a clinical trial.

The association between fecal incontinence and urinary incontinence is well established: the presence urinary incontinence increases the risk for fecal incontinence ranging between 2- and 4-fold. Combined urinary and fecal incontinence prevalence rates have been published for community-dwelling women and women with other pelvic floor disorders but has not been reported in women undergoing stress incontinence surgery. In a recent review on dual incontinence, the prevalence of fecal incontinence in women with urinary incontinence was found to be between 9% and 26%. In 603 parous women with weekly urinary incontinence who had an IIQ score above the 75th percentile for the group, 18% reported fecal incontinence at least once per month. Therefore, the prevalence of fecal incontinence in this sample of women with urinary incontinence who were undergoing surgery for stress urinary incontinence is consistent with dual incontinence rates in other studies. Our data emphasize the need for a thorough review of fecal incontinence symptoms in patients being considered for SUI surgery.

We identified risk factors that were predictive of monthly fecal incontinence in women having SUI surgery: (1) decreased contractile strength of the external anal sphincter on physical examination; (2) perimenopausal status; and, (3) prior urinary continence surgery/treatment. Decreased contractile strength of the external anal sphincter is not surprising in women with fecal incontinence and may result from anatomic disruption of the anal sphincter muscle and/or neuromuscular injury. Other studies have found an association between external anal sphincter disruption on endoanal ultrasound and fecal incontinence symptoms but not specifically on anal sphincter examination in women presenting for SUI surgery. Hormonal status may influence fecal incontinence and has been found to be associated with the presence of fecal incontinence in other studies. Further investigation is needed to determine the role of hormonal changes on both urinary and fecal continence mechanisms.

Women in our study who had prior urinary continence surgery or treatment were more likely to report monthly fecal incontinence. Although this association between prior continence treatment and/or surgery and fecal incontinence cannot be explained from our study results, it may be that women who had prior continence surgery had more severe pelvic floor injury, resulting in more pelvic floor symptoms, such as dual incontinence. Women with pelvic floor disorders are more likely to have bothersome fecal incontinence than women without pelvic floor disorders. A higher UDI score may also indicate more bothersome pelvic floor symptoms. Thus, women in this cohort may have more pelvic floor disorders, including fecal incontinence, and may be more likely to seek surgical treatment than women in other studies examining fecal incontinence risk factors.

This study differs from others that have examined risk factors for fecal incontinence for 2 main reasons: (1) women with predominant SUI may have different risk factors from those in the general population; and (2) SUI symptoms were severe enough to seek surgical treatment. In contrast to other investigators who examined fecal incontinence among general and clinical populations, we did not find an association between fecal incontinence symptoms and parity, mode of delivery, or BMI; however, this may be secondary to narrow range in parity (3.3 ± 1.8), the majority of women having vaginal deliveries (91%), and an overall trend for being overweight (BMI 30.3 ± 6.5 kg/m2).

Older age is consistently associated with an increased risk of fecal incontinence. In our cohort, older age was associated with monthly fecal incontinence in the univariate analysis; however, this factor did not remain significant in the multivariate analysis. This is likely secondary to our mean age (51.9 ± 10.3 years, range 27-81) and few women participants over the age of 65 years (n = 81, 12%); thus, limited power in the multivariate analysis existed to detect a significant change according to age decade. However, the increased risk associated with perimenopausal status may be a marker for age. The protective effect of detrusor overactivity on urodynamics in women with dual incontinence may be due to overall low numbers of women with dual incontinence (n = 8) who had this finding, and further evaluation is necessary prior to drawing any conclusions.

The results of this study are strengthened by the geographic diversity, ethnic diversity, and the large numbers of women studied in this 8-center surgical trial. The association we found between fecal incontinence and anal sphincter tone is strengthened by the fact that experienced personnel performed the anal sphincter examination and they differed from the personnel administering the fecal incontinence questions. Therefore, examiners and interviewers were blinded to each other’s data. Validated urinary incontinence instruments (UDI and IIQ) were used in our study to support the associations with fecal incontinence.

The limitations of this study include the lack of a standardized definition for fecal incontinence. Therefore, we defined the condition with an a priori decision to use only monthly fecal incontinence. Participants were asked about not only the presence or absence of flatal, liquid, and solid fecal incontinence but also the frequency of the condition. We chose to define fecal incontinence as liquid or solid leakage occurring at least monthly. We think this is a reasonable frequency that is likely to represent an event that is clinically relevant. We did not include flatal incontinence in the definition for 3 reasons: (1) Prevalence of flatal incontinence is high and including it dwarfs liquid and solid stool incontinence, which have been shown to affect quality of life more; (2) it may be diet dependent, and; (3) there is controversy about the voluntary vs involuntary nature of this condition. We cannot comment on severity or bother of fecal incontinence for our subjects because we did not use a condition specific fecal incontinence severity or quality-of-life instrument in this study of urinary incontinence.

The study is also limited by the relatively young age of our subject population (mean age 51 years). With an older population, prevalence rates would likely have been higher. The ability to generalize these findings to all women having stress urinary incontinence surgery is also a limitation, given the nature of recruiting and conducting a clinical trial.

Even with a strict definition for fecal incontinence, 16% of women presenting with SUI also have isolated liquid and solid fecal incontinence. Potentially, evaluation of fecal incontinence symptoms prior to surgical intervention for urinary incontinence could improve overall outcomes if both were addressed simultaneously.

Acknowledgments

Steering Committee
William Steers, MD, chair (University of Virginia, Charlottesville, VA); Ananias Diokno, MD, Salil Khandwala, MD (William Beaumont Hospital, Royal Oak, MI, and Oakwood Hospital, Dearborn, MI; U01 DK58231); Linda Brubaker, MD, MaryPat FitzGerald, MD (Loyola University Medical Center, Maywood, IL; U01 DK60379); Holly E. Richter, PhD, MD, L. Keith Lloyd, MD (University of Alabama, Birmingham, AL; U01 DK60380); Michael Albo, MD, Charles Nager, MD (University of California, San Diego, San Diego, CA; U01 DK60401); Toby Chai, MD, Harry W. Johnson, MD (University of Maryland, Baltimore, MD; U01 DK60397); Halina M. Zyczynski, MD, Wendy Leng, MD (University of Pittsburgh, Pittsburgh, PA; U01 DK 58225); Philippe Zimmern, MD, Gary Lemack, MD (University of Texas Southwestern, Dallas, TX; U01 DK60395); Stephen Kraus, MD, Thomas Rozanski, MD (University of Texas Health Sciences Center, San Antonio, TX; U01 DK58234); Peggy Norton, MD, Lindsey Kerr, MD (University of Utah, Salt Lake City, UT; U01 DK60393); Sharon Tennstedt, PhD, Anne Stoddard, ScD (New England Research Institutes, Watertown, MA; U01 DK58229); Debuene Chang, MD, John W. Kusek, PhD, Leroy M. Nyberg, MD, PhD (National Institute of Diabetes and Digestive and Kidney Diseases); Anne M. Weber, MD (National Institute of Child Health and Human Development).

Coinvestigators
Rowell S. Ashford II, MD; Jan Baker, APRN; Diane Borello-France, PT, PhD; Kathryn L. Burgio, PhD; Seine Chiang, MD; Ash Dabbous, MD; Patricia S. Goode, MD; Lee N. Hammontree, MD; David Lesser, MD; Karl Luber, MD; Emily Lukacz, MD; Shawn Menefee, MD; Pamela Moalli, MD; Kenneth Peters, MD; Elizabeth Sagan, MD; Joseph Schaffer, MD; Amanda Simsiman, MD; Larry Sirls, MD; Robert Starr, MD; R. Edward Varner, MD.

Study coordinators
Rosemary Bradt, RNC; Karen Debes, RN; Rosanna Dinh, RN; Judy Gruss, RN; Lynn Hall, RN, MSN, CURN; Alice Howell, RN, BSN, CCRC; Kathy Jesse, RN; D. Lynn Kalinoski, PhD; Kathryn Koches, RN; Barbara Leemon, RN; Karen Mislanovich, RN; Shelly O’Meara, RN; Janese Parent, RN; Norma Pope, RN; Caren Prather, RN; Terry Rogers, RN; Sylvia Sluder, CCRP; Mary Tulke, RN.

Biostatistical coordinating center
Kimberly J. Dandreo, MSc; Corinne J. Leifer, BA; Susan McDermott, MPH, GNP; Anne Stoddard, ScD (co–principal investigator); Sharon Tennstedt, PhD (principal investigator); Liane Tinsley, BA; Lisa Wruck, ScD; Yan Xu, MS.

References

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Presented at the 33rd Annual Scientific Meeting of the Society of Gynecologic Surgeons, Orlando, FL, April 12-14, 2007.

Alayne D. Markland DO, MSc, Stephen R. Kraus MD, Holly E. Richter MD, PhD, Charles W. Nager MD, Kimberly Kenton MD, MS, Lindsey Kerr MD, Yan Xu MS and Urinary Incontinence Treatment Network
Division of Gerontology, Geriatrics, and Palliative Care, Department of Medicine, University of Alabama at Birmingham School of Medicine, Birmingham, AL
Division of Women’s Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Alabama at Birmingham School of Medicine, Birmingham, AL
Department of Urology, the University of Texas Health Science Center at San Antonio, San Antonio, TX
Department of Reproductive Medicine, University of California, San Diego, Medical Center, San Diego, CA
Departments of Obstetrics & Gynecology and Urology, Loyola University Medical Center, Maywood, IL
Department of Urology, University of Louisville, Louisville, KY
New England Research Institutes, Watertown, MA
Received 17 January 2007;  revised 1 May 2007;  accepted 27 August 2007.  Available online 3 December 2007.