Validity and reliability of the SF-36 Health Survey Questionnaire in patients with coronary artery disease.

The validity and reliability of the SF-36 has been studied in 185 patients hospitalized with suspected ischemic cardiopathy, classified into four groups (AMI, unstable angina, nonischemic cardiologies, and absence of cardiologies). The validity of the construct has been analyzed by means of the association of the SF-36 with sociodemographic and clinical variables, and with diagnostic groups. The correlation of the subscales with GHQ-28 scores and the factorial structure have been studied. Internal consistency was measured by Cronbach's alpha and the item-internal consistency and item-discriminant validity. The validation result was as expected, although the scores were significantly lower in patients with unstable angina, only in the PF, VT, and GH subscales. The correlations with the GHQ-28 were high for MH and VT. The internal consistency was high (Cronbach's alpha 0.72-0.94). Factorial analysis identified eight factors, with the "anxiety" component of subscale MH remaining as an independent factor. These results suggest that the SF-36 is a useful scale for the differentiated clinical forms of ischemic cardiopathy, with the additional capability of reflecting the level of anxiety in these patients.