Association between biological aging and fecal incontinence, chronic diarrhea in U.S. adults: A retrospective cross-sectional analysis based on NHANES data.

ObjectiveTo investigate the associations of accelerated biological aging and its component biomarkers with chronic diarrhea (CD) and fecal incontinence (FI).MethodsThis cross-sectional study analyzed data from 5,443 participants in the 2005-2010 National Health and Nutrition Examination Survey (NHANES). PhenoAge was calculated using nine clinical biomarkers, and phenotypic age acceleration (PhenoAgeAccel) was derived from residuals obtained by regressing PhenoAge on chronological age (CA). Weighted t-tests and chi-square tests were used to compare baseline characteristics, and weighted logistic regression and restricted cubic splines (RCS) were used to analyze the associations. Subgroup analyses were performed to evaluate potential effect modification, and sensitivity analyses were conducted to assess the consistency of the main findings.ResultsPhenoAgeAccel was positively associated with FI, whereas no significant association was detected between PhenoAgeAccel and CD. Participants with FI had higher CA, PhenoAge and PhenoAgeAccel (P<0.05). FI prevalence increased across higher quartiles of PhenoAge and PhenoAgeAccel (P for trend<0.05). Fully adjusted models showed that Q4 of PhenoAge was associated with higher odds of FI than Q1 (OR = 2.559, 95% CI 1.012-6.468, P = 0.037). Similarly, Q4 of PhenoAgeAccel was associated with higher odds of FI than Q1 (OR = 1.571, 95% CI 1.097-2.250, P = 0.014). Participants with accelerated PhenoAge also had higher odds of FI than those with decelerated PhenoAge (OR = 1.417, 95% CI 1.084-1.851, P = 0.011). RCS analyses supported a significant positive linear association between PhenoAgeAccel and FI. Nine clinical biomarkers were evaluated for associations with FI. ALB (albumin), CRP (C-reactive protein), and RDW (red cell distribution width) showed significant linear associations with FI (all P for nonlinearity > 0.05), whereas LYM% (lymphocyte percentage) and MCV (mean corpuscular volume) showed significant nonlinear associations (all P for nonlinearity < 0.05). Creatinine (Cr), glucose (Glu), alkaline phosphatase (ALP), and white blood cell count (WBC) exhibited no significant associations with FI (all P for overall association > 0.05). Significant interactions were observed for age (P for interaction < 0.001) and diabetes status (P for interaction = 0.034), indicating that the PhenoAgeAccel-FI association varied according to these factors. Sensitivity analyses supported the robustness of the continuous PhenoAgeAccel-FI association, although statistical evidence weakened for quartile-based analyses.ConclusionsPhenoAgeAccel was significantly and linearly associated with FI in a nationally representative sample of U.S. adults, whereas no significant association was observed between PhenoAgeAccel and CD. Prospective studies are needed to confirm this association and clarify its temporal relationship.