Selecting a generic measure of health-related quality of life for use among older adults. A comparison of candidate instruments.

Selecting an outcomes assessment instrument requires knowledge of their relative merits, especially head-to-head comparisons. The authors compare health-related quality-of-life (HRQOL) instruments among older adults for their psychometric properties and subject burden, specifically the Sickness Impact Profile (SIP) and Medical Outcomes Study Short-Form 36 (SF-36). Subjects were 282 of 373 eligible older adults (75.6% response) ranging in age from 65 to 96. SIP scores demonstrated a strong skew toward low (good health) scores with a mean of 11.1% (+/- SD 11.5) on the Total SIP index score. Similar components of the SIP and SF-36 were moderately to strongly correlated. The SIP suffered from a ceiling (good health) scaling effect, and the SF-36 scales also demonstrated some scaling extremes. These results demonstrate the relative scaling limits, especially the ceiling effect, of the SIP compared to the SF-36, and in general, the SF-36 is preferred for use among community-living older adults.