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

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.

Cross-sectional study.

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.

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.

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.