Influence of Muscle Strength in Women With Urinary Incontinence on Health and Quality of Life

INTRODUCTION: Urinary incontinence (UI) is a common, yet debilitating, condition in older adults. Greater than 49% of women endorsed urinary incontinence in a United States national survey, and that population is expected to rise with the increasing life expectancy. The process of aging is often also paralleled by loss of muscle strength. The loss of muscle strength can be evaluated using two different criteria: sarcopenia and dynapenia. Sarcopenia is characterized by reduced strength and also the loss of muscle mass. It has long been used in the elderly population to screen for adverse health outcomes including urinary incontinence. It is estimated that 11–50% of people aged 80 and older meet criteria for sarcopenia. Dynapenia, on the other hand, is less studied in the urinary incontinence population. Dynapenia is characterized by reduced muscle strength with preserved muscle mass. This research incorporates a comprehensive set of “gold standard” assessments to measure low muscle strength, including both dynapenic and sarcopenic individuals, in a population with known urinary incontinence. OBJECTIVE: The primary outcome of this study is to examine the prevalence of low muscle strength in women with urinary incontinence using a patient population obtained from the state-wide database. Secondary outcomes include comparing physical function measures using age and sex matched z-scores as a standard reference from data as well as examining the impact these features have on quality of life (QOL) using validated QOL questionnaires. Investigating these associations may help lead to more awareness in clinical practice to better identify LMS in women with UI to expedite treatment/preventative measures. METHODS: This retrospective observational study analyzes female participants with urinary incontinence using a state-wide database. Participants were selected using ICD-10 codes for urinary incontinence diagnoses. Participants were divided into normal and low muscle strength using hand grip strength measures. Physical function measures and quality of life measures were evaluated using standardized assessments and surveys. Appendicular lean muscle mass was assessed using x-ray absorptiometry (DXA). Quality of life was measured using Patient-Reported Outcomes Measurement Information System (PROMIS) and 36-Item Short Form Health Survey (SF-36). RESULTS: Twelve percent of the UI population was classified as having low muscle strength. This population exhibited slower usual gait speed (p=0.004), slower fast gait speeds (p=0.004), and reduced muscle power. Quality-of-life scores and physical activity levels were also lower in this group, although not statistically significant. Type of UI showed no relation to muscle strength. Of this group, the majority had preserved muscle mass meeting criteria for dynapenia. CONCLUSIONS: Given the greater proportion of dynapenia than sarcopenia in the low muscle strength group, this may be a more specific risk marker for urinary incontinence. Decreased physical function compared to healthy age-matched peers and decreased quality of life in those with urinary incontinence and low muscle strength support early intervention. Larger studies are needed to explore this link.