Health status measures: strategies and analytic methods for assessing change scores.

Over the last 15 years, numerous self-report health status measures have appeared in the literature. An important parallel development has been the development of numerous strategies for assessing change in health status over time. The purpose of this article is to summarize and critique the more common design and analytic strategies for assessing the meaningfulness of change over time. Five commonly reported designs are presented, critiqued, and depicted using examples from the literature. Methods for analyzing results are reviewed and illustrated using two data sets. Insights into comparing competing health status measures are provided. In summary, the article suggests that some designs and analytic strategies are more adept than others at assessing change and that these methods should be considered when planning sensitivity-to-change studies.