Fecal Incontinence as a Marker of Multisystem Cardiopulmonary-Kidney Disease and Mortality in US Adults: : A Nationally Representative Cohort Study.

Objective: To determine whether fecal incontinence is associated with cardiovascular, pulmonary, and kidney disease, individually and in combination, and with all-cause mortality among community-dwelling US adults. Methods: Nationally representative cohort study using the National Health and Nutrition Examination Survey (NHANES) 2005-2010 with linkage to the National Death Index through December 31, 2019. The analytic cohort comprised 14,731 adults aged 20 years or older, with 14,718 eligible for mortality analysis. Fecal incontinence, defined as accidental leakage of mucus, liquid stool, or solid stool during the prior 30 days. A composite cardiopulmonary-kidney (CPK) burden was calculated as the count of three affected systems: cardiovascular disease (self-report), pulmonary disease (current asthma, emphysema, or chronic bronchitis), and kidney disease markers (estimated glomerular filtration rate <60 mL/min/1.73 m², urine albumin-creatinine ratio ≥30 mg/g, or self-reported kidney disease). Multisystem CPK burden was defined as ≥2 affected systems. Survey-weighted prevalence ratios (PRs) for each cardiopulmonary-kidney outcome from modified Poisson regression and hazard ratios (HRs) for all-cause mortality from Cox proportional hazards models, with sequential adjustment for sociodemographic, cardiometabolic, and shared functional/mood/urinary factors. Results: Among 14,731 adults (weighted mean age 46.8 years; 51.2% women), the weighted prevalence of fecal incontinence was 8.4% (95% CI, 7.8%-9.0%). Adults with fecal incontinence were nearly a decade older than those without (mean age 55.6 vs 46.0 years) and had higher prevalences of urinary incontinence (62.0% vs 32.6%), depressive symptoms (17.4% vs 6.2%), and functional limitation (30.3% vs 13.8%) (all P<.001). After full adjustment, fecal incontinence remained associated with kidney disease markers (PR, 1.16; 95% CI, 1.02-1.32) and with simultaneous involvement of all three CPK systems (PR, 2.38; 95% CI, 1.47-3.86). During follow-up, 2,395 deaths occurred. Crude mortality was 80.8 per 1,000 person-years among adults with both fecal incontinence and multisystem CPK burden, versus 10.6 in adults with neither. After adjustment, multisystem CPK burden alone (HR, 1.80; 95% CI, 1.58-2.04) and combined fecal incontinence plus burden (HR, 2.14; 95% CI, 1.66-2.77) predicted mortality. Fecal incontinence alone did not (HR, 1.06; 95% CI, 0.87-1.28). With multisystem CPK burden as the reference, the combined group did not demonstrate a statistically significant mortality increment (HR, 1.19; 95% CI, 0.92-1.54; P=.18). Conclusions and Relevance: Fecal incontinence in US adults is associated with disproportionate cardiopulmonary-kidney disease, functional impairment, and mortality, but the association with mortality was related to multisystem disease rather than to bowel symptoms themselves. Disclosure of fecal incontinence is a low-cost clinical signal that warrants integrated systemic assessment, including routine kidney function testing, rather than purely anorectal evaluation.