The Impact of Obesity and Weight Loss on Urinary and Bowel Incontinence Symptoms in Women

Introduction

Obesity has become a worldwide problem, being recognized as a “global epidemic” by the WHO in 1997.¹ In 1990, among states participating in the Behavioral Risk Factor Surveillance System, none had obesity rates ≥ 15%. In contrast, 2009 data demonstrated only one state had obesity rates less than 15%.² Currently, the combined age-adjusted prevalence estimates for US adults classified as overweight or obese (BMI ≥ 25) is 68.0%³ and for women is 64.1%.⁴ In women 60 years of age and older, 68.6 % (95% CI 64.4–72.7) are overweight or obese. Obesity, one of the leading health issues in US, results in approximately 300,000 deaths per year⁵, costing the United States about $147 billion⁶ dollars in medical care costs in 2008.

Obesity is associated with higher rates of hypertension, diabetes mellitus, hypercholesterolemia, osteoarthritis, coronary artery disease, and other chronic medical conditions.⁴ In recent years, studies have identified obesity as an independent risk factor for pelvic floor disorders, including urinary (UI) and fecal incontinence (FI); both of which are complex and under-diagnosed problems with physiologically and socially devastating consequences.⁷ Additionally, evidence has evolved demonstrating an association between weight loss and lifestyle changes helping to control UI, ^7–9 and possibly improving FI symptoms¹⁰. The goals of this paper are to present a summary of the current literature describing the effects of obesity and weight loss as it relates to urinary and fecal incontinence in women.

Pathophysiology

Although the exact etiology of pelvic floor disorders is unknown, investigators have demonstrated increased intra-abdominal pressures in individuals with excess body weight.¹¹ This, in association with upright posture, increases the pressure on the pelvic floor, including increased bladder and bowel pressure. This sequence of events is felt to potentially lead to stress UI (SUI-leakage associated with activities such as coughing, running and laughing; as well as aggravate symptoms of detrusor instability and urgency urinary incontinence (UUI - leakage associated with a strong urge difficult to defer). Obesity may also contribute an element of chronic strain and stretching, thus weakening the muscles, nerves and other pelvic floor structures involved in bladder and bowel function.¹²

Urinary Incontinence

Urinary incontinence (the inability to control urinary flow) affects nearly 50% of middle aged and older women⁹, with an estimated treatment cost of $19.5– $30 billion dollars per year. This is greater than the annual costs of treatment for breast, ovarian, cervical and uterine cancers combined.¹³ UI affects an estimated 12.7 million women and has profound consequences on quality of life, including social isolation, stigmatization, depression and the end of independent living for some older women.^14–15

Obesity has been identified as a significant independent risk factor for UI in postmenopausal women, and has been identified as the largest attributable risk factor for daily urinary incontinence.^16–17 Specifically, obesity is an independent risk factor for SUI and mixed urinary incontinence (having both SUI and UUI).

Weight Loss and UI

A beneficial effect of weight loss on UI prevalence has been found in surgical and behavioral weight reduction interventions.¹⁸ Epidemiological studies have consistently identified obesity as an independent risk factor both incident and prevalent urinary incontinence. A review article summarizing studies investigating the relationship between UI and obesity, demonstrated a dose-response effect of weight on UI.¹⁹ A 5-unit increase in BMI is associated with a 20% to 70% increase in the risk of UI, the maximum effect of weight rarely exceeding an odds ratio (OR) of greater than 4 to 5 in well controlled analyses. Similarly, incident UI over 5 to 10 years, increased by approximately 30% to 60% for each 5-unit increase in body mass index.²⁰ It was also noted that there may be a stronger association of increasing weight with prevalent and incident SUI, including MUI, than with UUI and overactive bladder syndrome (a bladder condition including urgency, frequency, urgency urinary incontinence and nocturia). Weight loss studies have indicated that surgical and non-surgical weight loss approaches may lead to significant improvements in UI symptoms.

Non-Surgical Weight Loss

Behavioral weight loss programs are effective in decreasing the frequency of UI.⁸ Several case series and prospective cohort studies have reported that non-surgical weight loss is associated with a significant decrease in the incidence and severity of UI, while Level 1 data exists supporting the finding that weight loss can be used as a first-line treatment for UI. (Table).^8,20–21

Table.

Non-surgical Weight Loss Randomized Trials for Urinary Incontinence Treatment^£

References	N	Design	BMI or Wt Change	UI Prevalence or Episode Change (p value)
Subak et al 8	39	RCT, 2 arms: Immediate intervention: weight reduction intervention x 3 mo (n = 20) Wait list control: delayed intervention (n=19) Weight reduction intervention: 3-month intensive group based medical and behavioral weight loss program combined with low calorie (800 kcal/day) liquid diet Wait-list control group: no intervention for 3 mo and then entered the weight reduction program. All subjects followed for 6 months after completing the weight reduction program	Immediate intervention group achieved a median weight loss of 16 kg (IQR 9 to 20) compared with 0 kg (IQR −2 to 2) in the wait-list control group (p <0.0001). BMI reduction from 35 (IQR 31 to 40) to 28 kg/m2 (IQR 26 to 34) or 16% in the immediate intervention, no change in the wait-list control group (p <0.0001).	Number of weekly UI episodes at 3 mos decreased 60% in immediate intervention vs 15% in control (<0.0005) Number of stress (0.003) + urge (0.03) UI episodes decreased in immediate vs control Control had intervention after 3 mos with 71% wkly UI decrease after wt loss Incontinence Impact Questionnaire + Urogenital Distress Inventory scores significantly improved after wt loss
Subak et al 20	10	Low calorie liquid diet wt loss program, 3-mo follow-up	Pre BMI 38, post BMI 33 kg/m2, mean weight loss, 15 kg (<0.03)	Decrease from 13 to 8 UI episodes/wk after wt loss (<0.07). Of 10 women, 6 with 5% or greater body wt loss had greater than 50% UI frequency decrease (<0.03)
Brown et al21	1,957	RCT 3 arms: - lifestyle intervention* (n = 660) - metformin (n = 636) -placebo (n= 661) mean 2.9-yr follow-up	Wt loss of 3.4 kg versus 1.5 kg versus 0.5 kg in groups 1–3, respectively (<0.001)	Weekly UI prevalence after treatment 38% versus 48% versus 46% in groups 1–3, respectively (p = 0.001)

^£Adapted from Subak, Richter and Hunskaar, 2009

^*Diet, exercise and behavior modification program; RCT: randomized controlled trial; IQR: interquartile range

A more recent large randomized controlled trial addressed weight loss as a first line treatment for overweight and obese women with UI.⁹ Between July 2004 and April 2006, 338 women with a BMI of 25– 50kg/m² reporting at least 10 episodes of UI in a 7-day period were recruited. In this single-blind, randomized controlled trial, participants were randomized 2:1 to undergo an intensive 6-month weight loss program of diet, exercise and behavior modification (n=226) or a structured education program (control group; n=112). Each group also received an instructional booklet describing standard behavioral therapy for UI. After 6 months, women in the intervention group achieved a mean weight loss of 8.1% compared with 1.8% in controls (p <0.001). The mean number of weekly incontinence episodes decreased by 47.4% compared with 28.1% in the control group (p = 0.01). This decrease was mainly attributed to a decrease in the number of stress incontinence episodes (57.6% vs. 32.7%; P < 0.02). Although the decrease in frequency of UUI episodes was larger in the treatment versus the control (42.4% vs. 26.0%) these results were not statistically significant (p = 0.14). Subjective data including patient reported symptoms and symptom specific quality of life were also significantly improved in the intervention group. At 6 months, women in the weight loss group perceived greater improvement in the frequency of UI, lower volume of urine loss and viewed UI as less of a problem and higher satisfaction with the change in incontinence at 6 months compared to women in the control group (p <0.001).

Surgical Weight Loss

Surgery is not usually the first line treatment approach for weight loss, but in certain medical situations (i.e. BMI > 40 or BMI 35–39.9 associated with diabetes) is indicated.²² Several observational studies have demonstrated that surgically induced weight loss in morbidly obese individuals (> 45kg above ideal body weight) losing 45 to 50kg, experienced resolution of UI symptoms.^{10, 11, 23–26} Bump et al¹¹ reported significant improvements in UI symptoms in women (mean pre-operative BMI of 49.9 kg/m2) 1 year after surgically induced weight loss. Thirteen subjects underwent comprehensive evaluation of lower urinary tract function before and one year after surgically induced weight loss. Significant changes were seen in urodynamic parameters, number of incontinence episodes, and the need to use absorptive pads. Of 12 subjects who complained of UI before surgery only three complained of UI post surgery (p = 0.004) and only one requested treatment after weight loss.

In a surgical series of 101 obese women (mean preoperative BMI of 48.8 kg/m²), Burgio et al.¹⁰ reported a significant reduction in the prevalence and severity of UI symptoms (using validated symptom specific QoL questionnaires) 6 and 12 months after laparoscopic Roux-en-Y surgery. The prevalence of UI decreased from 66.7% before surgery to 41% at 6 months and 37% at 12 months, with the reduction in the prevalence of UI proportional to the magnitude of weight loss.

More recently, it has been reported that women who have undergone laparoscopic gastric banding have had significant improvements in lower urinary tract symptoms. 142 women who had undergone laparoscopic gastric banding surgery at a single center in Newcastle, Australia were surveyed.²⁶ There were significant improvements in the International Consultation on Incontinence-Urinary Incontinence-Short Form (ICIQ-UI-SF) with respect to urinary symptoms (female pre ICIQ-SF score 5.24 v. post 3.93, P= 0.0008) and Quality of Life (P < 0.0001) scores. For each kilogram lost there was a 0.05 unit improvement in the ICIQ-SF score (P= 0.03). (The ICIQ-SF is a validated questionnaire designed to asses the impact of UI on a person’s life. The scoring range is 0–21; a higher score correlates to a greater impact of incontinence.) Although there were improvements in SUI, UUI symptoms worsened, after adjusting for weight loss.

Fecal Incontinence

Fecal incontinence is defined as the involuntary loss of liquid or solid stool that causes a social or hygienic problem.²⁷ The prevalence of FI varies considerably depending on the population studied and the definition of incontinence used. In clinic-based studies, such as general medicine or gynecology, the reported prevalence has varied from 5.6 to 28 percent²⁸ and in nursing home studies, reported rates are as high as 47%.²⁹ In contrast, population-based studies of community-dwelling older adults report the prevalence of fecal incontinence ranging from 3.0% to 16.9%,³⁰ depending on the age of the population. The higher estimates in gynecology clinics and nursing homes are consistent with common assumptions regarding females, the older woman, and the infirm being disproportionately affected by the condition.

As the pathophysiological mechanisms responsible for the development of UI and FI may overlap (nerve and sphincter damage), an association between the two would be expected. Population-based studies have demonstrated that up to 50% of patients with FI also have UI (double incontinence) and the risk of FI in individuals with UI may be increased by up to six fold.^31–32 Less is known about the relationship between obesity and FI. In a population based study of 2,109 randomly selected middle-aged and older females (average age, 56 years) subjects reported the level of bother and impact on quality of life from FI. ³³ Potential risk factors were assessed by self-report, patient interview, physical examination, and medical record review. A final multivariable model comparing any FI in women in the past year to those without showed that obesity was independently associated with a 20% higher prevalence of FI per 5-unit increase in BMI.

Weight Loss and Fecal Incontinence

A 2005 study found a particularly high prevalence of anal incontinence (involuntary loss of liquid/solid stool, mucus and gas) in a cohort of 178 morbidly obese (body mass index [BMI] 40 kg/m² or more) women undergoing consultation for bariatric surgery.³⁴ In this study, symptoms of anal incontinence were noted in one third (32%) of morbidly obese women, more than that reported in population based studies. If flatal incontinence was excluded, that rate fell to 19.4 % (only slightly above the rate for population based studies). In a follow-up study of this patient population, 101/178 of these women (aged 20–55 years) undergoing laparoscopic Roux-en-Y gastric bypass,¹⁰ FI symptoms were assessed 6 and 12 months post surgery. The prevalence of FI decreased from 19.4% baseline to 9.1% at 6 months and 8.6% at 12 months (p=.02). Interestingly, the prevalence of flatal incontinence increased from 12.9% preoperatively to 20.8% at 6 months, and 30.1% at 12 months (P=.004).

In contrast, some studies have shown an increase in FI symptoms after bariatric surgery. Roberson and colleagues reported the results of a study evaluating weight loss on FI symptoms utilizing a detailed survey mailed to all 404 adults who underwent bariatric surgery.³⁵ The survey considered type of surgery, weight change, symptoms of bowel and bladder disorders, and perceived effects of surgery on those symptoms. Type and severity of fecal incontinence was obtained using previously validated questionnaires. Of 194 patients who responded (82% female), 51.2% who had FI prior to surgery said their conditioned worsened afterward, compared with only 9.3% who reported improvement after surgery. Fecal incontinence was common in both men and women with 48% of the women and 42% of the men reporting liquid stool incontinence and 21% of the women and 30% of the men reporting solid stool incontinence. 55% of the women and 31% of the men with fecal incontinence perceived worsening after surgery. Women with diarrhea were four times more likely to report fecal incontinence (P < 0.0001). Furthermore, women who perceived worsening of diarrhea after surgery were significantly more likely to have fecal incontinence (P = 0.003), suggesting that FI in this population may partially be due to an underlying weakness in continence mechanisms which is clinically unmasked after surgery because of altered diet or anatomic changes in the gastrointestinal tract. More well controlled studies are needed to explore the impact of obesity and weight loss on FI symptoms.

Conclusion

Among the many medical conditions affected by obesity are pelvic floor disorders, inclusive of urinary and fecal incontinence. Weight loss as a first-line treatment for urinary and fecal incontinence should be considered in all women along with consideration of the addition of other concomitant behavioral treatment approaches including pelvic muscle exercises, attention to types and amounts of fluid intake and voiding habits. Even if weight loss is unsuccessful in treating UI, subsequent continence surgery, if indicated, may be technically easier and potentially safer secondary to weight loss. Caution should be taken, however, that although an intervention such as weight loss could be supported as first-line therapy, general practitioners should not allow this to delay referral to a specialist who can provide these women with appropriate evaluation and the full spectrum of treatment modalities for their UI and FI symptoms.