Functional Profile Differences Across Diagnostic Categories Using WHODAS 2.0 in Adults with Neurological, Musculoskeletal, and Chronic Pain Conditions

<b>Background</b>: Functional disability is a growing concern in aging populations with chronic health conditions, yet few studies have compared disability profiles across diagnostic categories using standardized tools. <b>Objectives</b>: This study aimed to characterize the functional profiles of adults with neurological, musculoskeletal, and chronic pain conditions using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) and to examine differences by age and sex. <b>Methods</b>: A total of 419 participants (median age = 73 years; 73% female) completed the 36-item WHODAS 2.0. Diagnoses were classified into three groups: neurological (<i>n</i> = 134), musculoskeletal (<i>n</i> = 230), and pain-related (<i>n</i> = 55). Domain-level scores were analyzed using non-parametric tests and Spearman correlations. <b>Results</b>: revealed that neurological conditions were associated with the highest disability levels, particularly in cognition, interpersonal relations, and participation. Musculoskeletal conditions showed greater impairments in mobility and self-care, while pain-related conditions demonstrated variable disability, especially in participation. Women reported higher disability scores in the neurologic group, with significant differences observed in the cognition domain among neurological cases (<i>p</i> = 0.048). Age was positively correlated with disability in self-care and mobility, especially in musculoskeletal conditions. <b>Conclusions</b>: These findings highlight the utility of WHODAS 2.0 in identifying domain-specific limitations across clinical populations. They support the need for individualized, diagnosis- and gender-sensitive rehabilitation strategies, and suggest that WHODAS 2.0 can inform targeted care planning and resource allocation in rehabilitation settings. Future research should incorporate longitudinal designs and explore contextual factors influencing functional outcomes.