Measurement characteristics for two health-related quality of life measures in older adults: The SF-36 and the CDC Healthy Days items.

The sample was limited to adults aged 65 or older, most of whom were white women enrolled in Medicare Advantage plans, so results may not apply to younger adults, other racial or ethnic groups, or traditional Medicare beneficiaries. The study compared measurement relationships; it did not test whether using these measures improves patient care or outcomes. The statistical models did not fit perfectly, so the relationships among items and health factors are approximate. CDC Healthy Days items can be affected by people preferring certain numbers, scores bunching at the high or low end, and a focus on the past 30 days, which may make them less sensitive to change over time. The items ask about unhealthy days and do not cover positive aspects of health.

The study did not receive financial support, and the authors reported no conflicts of interest.

Do not conclude that CDC Healthy Days items replace physical function assessment. The physically unhealthy days item was not associated with the SF-36 physical functioning subscale, so function-specific problems may be missed.