A New Measure for Continuity of Care: The Alpha Index

Abstract

Continuity of care, and in particular provider continuity, is increasingly becoming a central aim of health care policy in a majority of clinical settings. Over the past three decades, a number of statistics have been introduced to provide a quantitative measure of continuity, but generally speaking, all existing continuity measures each reflect either the concentration of providers or the sequential continuity in a series of patient visits-none reflect both. Since concentration is often considered as important as consecutiveness, an improved index, termed the alpha index, is introduced here. In simple terms, the alpha index is a weighted average of the concentration of providers and the sequential continuity. By combining these two aspects of continuity with a user-specified weight, alpha, this new index can be more satisfactory in evaluating overall levels of continuity of care. In this article, the underlying concepts of this new measure, as well as its statistical properties such as bias and consistency, are discussed analytically. Numerical examples are given to illustrate the results.