Comparing short form and RAND physical and mental health summary scores: Results from total hip arthroplasty and high-risk primary-care patients

OBJECTIVES: Summary physical health scores for the Short Form (SF) measures are computing using positive weights for physical items and negative weights for mental health items. Mental health summary scores use positive weights for mental items and negative weights for physical. The RAND Health Status Inventory (HSI) measures do not use negative weights. Do these different approaches to scoring matter? The objective was to compare summary scores using both the SF and RAND-HSI. METHODS: SF-36 and the Health Utilities Index Mark 3 (HUI3) were administered to a cohort of patients waiting for elective total hip arthroplasty (THA). SF-12 and HUI3 were administered to a cohort of high-risk primary-care patients. Summary scores were generated and compared. Single-attribute utility scores for emotion in HUI3 were also computed. Canadian and US norms for SF, RAND-HSI, and HUI3 were used to interpret results. RESULTS: For THA patients, mean physical health scores were 28 and 36 for SF and RAND-HSI. Mean mental health scores were 55 and 42. For the primary-care patients, the scores were 34 and 36 for physical and 46 and 40 for mental health. CONCLUSIONS: SF and RAND-HSI provided somewhat similar summary scores in the THA study. However, SF and RAND-HSI mental health scores differed in the primary-care patient cohort and results from HUI3 corroborate the mental health deficits identified by the RAND-HSI. It may be wise for investigators to use both SF and RAND-HSI scoring systems.