Empirical evaluation of an ICF core set for managing musculoskeletal conditions in primary care physical therapy services in Spain: a multicenter study.

Background: Musculoskeletal conditions are a leading cause of disability, yet functioning is not routinely documented in primary care. A setting-specific International Classification of Functioning, Disability and Health (ICF) Core Set may facilitate biopsychosocial assessment by identifying domains relevant to patients and physical therapists. Objective: To empirically evaluate category retention and perceived relevance within a specific ICF Core Set for musculoskeletal conditions in primary care physical therapy and examine correspondence and differences between patient-reported and physical therapist-assessed perspectives. Methods: A multicenter, cross-sectional study included 387 patient-physical therapist dyads from the public regional healthcare service of Castilla y León (SACYL), Spain. Both perspectives rated 34 ICF categories using a 100 mm VAS. ICF categories with ≥5% prevalence were retained. Sensitivity analyses examined retention across WHODAS 2.0 and Self-administered Comorbidity Questionnaire (SCQ) levels and their continuous associations with ICF summary ratings. Paired perspectives were compared using Wilcoxon signed-rank tests with Holm-adjusted Results: All 34 ICF categories exceeded the retention threshold (23.3-94.3%) and remained retained for all disability and comorbidity subgroups. WHODAS 2.0 showed moderate positive correlations with Body Functions and Activities and Participation ratings (Spearman's Discussion: The findings provide empirical support for retaining the 34 categories and indicate generally substantial group-level correspondence alongside potentially informative individual differences. Further research should evaluate measurement properties, feasibility, responsiveness, and implementation in routine primary care.