The patient-based evaluation of outcome is gaining increased importance. The aim of the study was to translate and culturally adapt the short musculoskeletal function assessment questionnaire (SMFA) into German and to evaluate the practicability, metric properties, and distribution characteristics of the German version (SMFA-D).
The SMFA is a questionnaire on the functional status of the musculoskeletal system of patients consisting of a function index (34 items) and bother index (12 items) with a 5-point response format. The SMFA was independently translated by orthopaedic-trained, qualified German- and English-speaking translators. A consensus committee review and selection of an optimally comprehensible German version was performed. Patients checked this version for comprehensibility and time to complete the questionnaire. 40 fluently German-speaking patients with primary osteoarthritis of the knee completed the SMFA-D twice at a one week interval. The test-retest reliability and internal consistency were evaluated. The values are standardized on an scale from 0-100. High values indicate a poor function.
The SMFA-D is comprehensible and can be completed within 20 minutes in the mean. There were no skewness and no floor or ceiling effects. The mean function index was 47 (SD 17, range 16-80). The mean bother index was 44 (SD 19, range 5-75). Test-retest reliability were 0.88 (function index) and 0.71 (bother index), respectively. Internal consistency (Cronbach's alpha) was 0.92 (function index) and 0.88 (bother index), respectively.
The SMFA-D is a practical and reliable questionnaire for patient-based evaluation of functional problems of the musculoskeletal system.