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BackgroundThe aims of the present study were first to detect MCID for WOMAC in a Moroccan population, and second, to identify the best pre-treatment predictors on the change of health after treatment by non-specific, non-steroidal anti-inflammatory drugs (NSAIDs), and to evaluate whether the predictors were dependent on the choice of the response criterion.MethodsThe study involved 173 patients with osteoarthritis in whom primary care physicians decided to start treatment with non-selective NSAIDs. Assessments at admission and after 6 weeks were conducted. In order to determine the threshold levels associated with a definition of clinically important improvement, the receiver operating characteristic method was used. Three different measures of response to a 6-week NSAIDs treatment were used: one indirect measure (MCID in the total WOMAC score), one direct measure (transition question) and a combination of both criteria.ResultsEighty patients (46.3%) reported "a slightly better" general health status compared to that of 6 weeks before NSAIDs treatment. The MCID proportion is a 16.0% reduction in WOMAC. The most stable pre-treatment predictors on the improvement of health after treatment by NSAIDs were the absence of previous knee injury and a high level of education.ConclusionsIn our data, a 16.0% reduction of the total WOMAC score from baseline was associated with the highest degree of improvement on the transition scale category. This cut-off point had good accuracy, and should be appropriate for use in the interpretation of clinical studies results, as well as in clinical care.

The objectives of this study are to translate, adapt in the Moroccan cultural context, and validate in patients with ankylosing spondylitis (AS) the Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). The cross-cultural adaptation of the BASFI and BASDAI was obtained in accordance with the guidelines for translation of the health status measures. Eighty-five patients with AS were included in the study. The test-retest reliability and the internal consistency were analyzed, and both questionnaires were assessed for external construct validity. Structural validity was analyzed with correlation matrix. Twenty-four-hour test-retest reliability was good: BASFI intraclass correlation coefficient (ICC) = 0.96 (confidence interval (CI) at 95%, 0.93-0.97), BASDAI ICC = 0.93 (CI at 95%, 0.90-0.95). Cronbach's alpha was 0.90 for the BASFI and 0.86 for BASDAI. The construct validity of the instruments was evaluated. The BASFI showed a strong validity when correlating its results with Schober's test (r = -0.56), occipital wall distance (r = 0.46), chest expansion (r = -0.46), BASDAI (r = 0.54), Bath Ankylosing Spondylitis Metrology Index (r = 0.70), Bath Ankylosing Spondylitis Global Score (BAS-G; r = 0.58), Bath Ankylosing Spondylitis Radiology Index (r = 0.61), and the radiological changes in sacroiliac joints (r = 0.54). A good correlation was observed between the BASDAI and the spinal pain (r = 0.53), the number of nocturnal awakenings (r = 0.57), the morning stiffness (r = 0.65), the enthesic index (r = 0.47), the BAS-G (r = 0.53), the BASFI (r = 0.54), and the erythrocyte sedimentation rate (r = 0.41; for all p < 0.001). The correlation matrix showed an intermediate correlation between items. The Moroccan version of the BASFI and the BASDAI showed adequate reliability and validity. These instruments can be used in the clinical evaluation of Moroccan and Arabic-speaking patients with AS.