The XSMFA-D (German Extra Short Musculoskeletal Function Assessment Questionnaire) was developed on the basis of the SMFA-D to provide a short questionnaire for assessment of the functional status from patient's perspective in routine use.
Based on psychometric and medical aspects 16 items were extracted from the SMFA-D during an iterative process. 633 SMFA-D questionnaires of 199 patients were used as basic data. The XSMFA-D was evaluated on 67/51 patients with primary osteoarthritis of the knee/hip undergoing total joint replacement.
The tests for reliability and internal consistency produced favorable results. The Knee Score, Harris Hip Score, WOMAC and SMFA-D showed significant correlations to the XSMFA-D indicating construct validity. The criterion validity could be demonstrated successfully by relations with external parameters like walking distance, patients reported pain, mobility judgements by physicians and degree of osteoarthritis. The discriminant validity could also be demonstrated by significant differences between several different patient groups. Almost all effect sizes were generally large.
The XSMFA-D could be demonstrated to be an appropriate short questionnaire for the evaluation of therapy results from patient's perspective. The use of the XSMFA-D can be recommended for routine use. Further investigations of the instrument will be undertaken.