COMPARING THE PERFORMANCE OF HEALTH-STATUS MEASURES FOR HEALTHY OLDERADMITS

OBJECTIVES: The specific goals of the study were to compare three heal th status measures among older adults for their correlations with simi lar scales and to examine whether extreme (positive) health states mig ht lead to measurement problems. We also report on practical administr ation and response problems among older adults. DESIGN: Eligible and r andomly selected health plan enrollees aged 65 and older were sent a b aseline survey about their health. A random sample of persons who retu rned this survey was recruited to participate in the comparative study . Additional questionnaires were completed by mail and telephone inter views. Measures were repeated at a 1-year follow-up mailing. SETTING: This study was conducted at Group Health Cooperative (GHC) of Puget So und, a large prepaid health maintenance organization. PARTICIPANTS: Su bjects were 200 of the 283 older adults selected (68.2% response). Mea n age was 72.5 years. MEASUREMENTS: The primary measures were the Sick ness Impact Profile (SIT), the Quality of Well-being Scale (QWB), and three scales of the Medical Outcomes Study Short-Form 36 (SF-36). Also included were a stress scale, the Positive Affect Scale, and the Chro nic Disease Score (CDS) computed from the automated pharmacy data. RES ULTS: SIP scores showed a very strong skew toward low (good health) sc ores with a mean of 3.4% (+/-SD 4.4). The QWB scores ranged from .50 t o .90 (mean .73+/-.09). For the MOS SF-36 scales, scores of 100 (good health) were common for both of the physical health scales but not for general health. Analyses showed the SIP, QWB, and MOS SF-36 scales we re moderately to strongly correlated with similar measurement scales a nd with the independent measure of chronic disease and psychosocial he alth. Scales repeated at 1 year were highly correlated: intraclass cor relation coefficients between baseline and 1 year ranged from an r = . 51 to .73. CONCLUSIONS: Our results suggest that the SIP is not a usef ul tool for rating healthy, community-dwelling older adults. Two MOS S F-36 measures used in this study showed some tendency for ''ceiling'' measurement effects. The QWB demonstrated an acceptable distribution o f scale scores; however, it is the most complex of the three measures to administer. Among the broad range of older adults, no one tool appe ars to apply to every situation.