Changes in the SF-36 in 12 months in a clinical sample of disadvantaged older adults

The present study assessed changes in the Medical Outcomes Study 36-item short-form health survey (SF-36) during a 12-month period and examined the relation of those changes to selected baseline characteristics.

The study was a 12-month follow-up evaluation of 786 disadvantaged adults aged 50 to 99 years old who had participated in a randomized controlled clinical trial in the general medicine outpatient clinics of a major academic medical center. Descriptive and psychometric analyses of changes in the SF-36 scale scores during a 12-month period were performed, and two series of multivariable logistic regressions of increases or decreases greater than one standard error of measurement (SEM) versus stability on selected baseline characteristics were done. Measures were the eight SF-36 scales.

Mean baseline scores on the SF-36 scales were substantially below age-specific national norms. Problematic floor and/or ceiling effects were found for the bodily pain, social function, role--physical, and role--emotional scales, consistent with age-specific national norms. Internal consistency was unacceptable for the general health perceptions scale, adequate for the social function scale, and good for all the other SF-36 scales. Improvements greater than one standard error of measurement were found for between one fifth and one third of the patients, and declines greater than one standard error of measurement were found for between one fifth and one third of the patients. Selected baseline characteristics generally were unrelated to either improvements or declines on the SF-36 scales.

The SF-36 scales appear to be sufficiently sensitive for measuring changes in health outcomes during a 1-year period in older patients with debilitating disease. Little of the measured change, however, was predictable.