Self-management programmes targeted at enhanced self-efficacy are progressively being emphasized as a cost-effective way of alleviating patients’ chronic illnesses. However, no measure of self-efficacy has been validated for chronic disease patients with varied cognitive failures. Chronic disease patients with complete data on cognitive failures and the SEMCD at their assessment between March and April 2016 in the southwest of Nigeria were used. Confirmatory factor analysis (CFA) was employed to assess the factor structure of the SEMCD scale. Reliability and parameter estimates of the scale were established using traditional Cronbach’s alpha and item response theory (IRT) analyses. A total of 1214 patients were included. CFA supported the single factor structure of the SEMCD scale (Fit index= 1.00, comparative fit index = 1.00, root mean square error of approximation = 0.00). Internal consistency was high (α=0.94). A unidimensional graded response model also supported a single scale scoring process for the survey and showed all items as worthy contributors to the measuring scale. Significant negative relationships of the scale with cognitive failures (r = -0.10, p<0.01) and for the construct validity, with measures of health status (r = -0.26 - -0.10; p<0.01) and health care utilization (r = -0.24 ─ -0.12; p<0.001) were found. Scores from the SEMCD scale are valid for measuring self-efficacy in chronic disease patients with varied cognitive failures. Results support the scale as an outcome measure to evaluate the effectiveness of self-management programmes in patients with diverse cognitive capacities
