Trajectories of health for older adults over time: accounting fully for death.

The process of healthy aging can best be described by plotting the trajectory of health-related variables over time. Unfortunately, graphs including data only from survivors may be misleading because they may confuse patterns of mortality with patterns of change in health. Two approaches for creating graphs that account for death in such situations are 1) to incorporate a category or value for death into the longitudinal health variable and 2) to measure time in years before death or some other event. The first approach has been applied to self-rated health (excellent to poor) and the 36-Item Short-Form Health Survey (SF-36). It allows for flexible and interpretable analyses and may be appropriate for other variables as well. The second approach also accounts fully for death, but the questions it can address are limited. Both approaches are useful and should be used at a minimum for supporting analyses in longitudinal studies in which persons die during observation.