Validation of a Quality of Life Instrument in Spanish Patients With Rheumatic Diseases: The Rosser Classification System

Objective: The aim of this study was to assess the reliability and validity of the Spanish version of the Rosser classification system for disease states in patients with musculoskeletal disorders.

Methods: Our study was based on a questionnaire validation design. Patients were attended at an outpatient rheumatology clinic at Hospital Clínico San Carlos, Madrid, Spain. The Rosser classification system was completed by the physician from the research team (PMQ) and by the patient (HMQ). Criterion standards: The EuroQol-5D for the HMQ and the physician global estimate (DOCGL) for the PMQ. Internal consistency reliability was assessed using Cronbach α. Test-retest reliability and interobserver reliability were analyzed using the intraclass correlation coefficient. The criterion validity between HMQ and EuroQol-5D and between PMQ and DOCGL was assessed using the Spearman correlation coefficient.

Results: The full analysis was based on 4 samples of patients (104 to 266 patients), most of whom were middle-aged women. For HMQ, Cronbach α was 0.70. Test-retest reproducibility was 0.7. With respect to criterion validity, significant correlations in the expected direction were observed. For PMQ, Cronbach α was 0.70, indicating excellent intraobserver and interobserver reliability. With respect to criterion validity, strong correlations were observed between the PMQ and the DOCGL.

Conclusions: The Rosser classification system showed satisfactory reliability and suitable criterion validity for patients with musculoskeletal disorders. The instrument seems to be suitable for clinical decision making and research.