Performance of the RAND-12 and SF-12 summary scores in type 2 diabetes

Objectives: To compare the performance of the RAND-12 and SF-12 physical and mental health summary scores, in a sample of people with type 2 diabetes, in distinguishing groups of differing disease severity. Methods: Summary scores from RAND-12 and SF-12 were compared between known subgroups defined in terms of treatment intensity, duration of diabetes, time lost from work and emergency room visits for diabetes. Multiple regression analyses were used to compare known groups. Results: Statistically significant and clinically important differences were observed across comparisons of the RAND-12 physical health composite (PHC), that were not apparent on the physical component score (PCS-12). RAND-12 mental health composite (MHC) scores were statistically significant according to treatment intensity and days off work due to diabetes, but differences in mental component score (MCS-12) scores failed to reach statistical significance for any of these comparisons. Conclusion: Interpretation of the SF-12 summary scores in our study would have overlooked seemingly important differences in health that were picked up by the RAND-12 summary scores.