Assessing health-related quality of life among coronary patients: SF-36 vs SF-12

Objective: to compare health-related quality of life (HRQL) assessed using the Short Form-12 (SF-12) and the Short Form-36 (SF-36) questionnaires in coronary patients with different diagnoses, testing the hypothesis that the SF-12 is capable of discriminating between patients with acute myocardial infarction (AMI) and patients with unstable angina in the same way as the SF-36. Study design: Cross-sectional study. Methods: HRQL was studied in 186 patients admitted to hospital for ischaemic cardiopathy, using the SF-36 and SF-12. Intraclass correlation coefficients were calculated for each summary component. The proportion of variability of the physical and mental summary components of the SF-36 (PCS-36 and MCS-36) explained by each component of the SF-12 was examined using a linear regression model, adjusted for age and gender. Results: The mean scores observed were similar in the two questionnaires. The degree of agreement was high, and the corresponding regression model explained 87% of the variability in the PCS-36 and 93% of the variability in the MCS-36. The SF-12 identified the differences between AMI and angina in the same way as the SF-36. Conclusions: The SF-12 replicates the information of the summary component scores of the SF-36, and discriminates between patients with AMI and those with unstable angina. Its use allows the same information to be obtained as from the SF-36, with less effort for the patient and the doctor. (C) 2009 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.