Expiratory Muscle Weakness and Stress Urinary Incontinence Severity in Community-Dwelling Older Adults: A Cross-Sectional Study

Abstract

Continence during effort depends on coordinated control of intra-abdominal pressure by the diaphragm, abdominal wall and pelvic floor, and respiratory muscle strength declines with ageing. This analytical cross-sectional study examined whether respiratory muscle strength and pulmonary function are associated with stress urinary incontinence (SUI) severity in community-dwelling older adults. One hundred and four adults aged 60–82 years (95 women, 9 men) with stress or stress-predominant mixed urinary incontinence were recruited consecutively. SUI severity was measured with the ICIQ-UI Short Form, maximal expiratory (MEP) and inspiratory (MIP) pressures with a digital manometer, and pulmonary function by spirometry. MEP correlated negatively with ICIQ-UI SF score (ρ = −0.37, 95% CI −0.52 to −0.19; p < 0.001), and the association persisted after adjustment for age, sex, BMI, parity and chronic cough (partial r = −0.36). MIP showed a weaker association (ρ = −0.25; p = 0.012), whereas spirometric indices were unrelated to severity. In multiple regression, MEP remained an independent predictor (β = −0.39; p < 0.001), adding 9% explained variance; each 10 cmH₂O lower MEP corresponded to a 0.8-point higher score. With MEP and MIP entered together, only MEP remained significant. Mean MEP declined from 81.7 cmH₂O in slight to 46.2 cmH₂O in very severe SUI (trend p < 0.001), and participants with MEP below the lower limit of normal (40%) had higher scores (12.2 vs 9.3; p = 0.002). Expiratory muscle weakness is an independent correlate of SUI severity in older adults, supporting respiratory muscle assessment in pelvic health evaluation.