Defining and measuring adherence to cancer screening

Background: The importance of cancer screening is well-recognized, yet there is great variation in how adherence is defined and measured. This manuscript identifies measures of screening adherence and discusses how to estimate them.

Discussion: We begin by describing why screening adherence is of interest: to anticipate long-term outcomes, to understand differences in outcomes across settings, and to identify areas for improvement. We outline questions of interest related to adherence, including questions about uptake, currency or being up-to-date, and longitudinal adherence, and then identify which measures are most appropriate for each question. Our discussion of how to select measures focuses on study inclusion criteria and outcome definitions. Finally, we describe how to estimate different measures using data from two common data sources: survey studies and surveillance studies. Estimation requires consideration of data sources, inclusion criteria, and outcome definitions. Censoring often will be present and must be accounted for.

Conclusion: We conclude that consistent definitions and estimation of adherence to cancer screening guidelines will facilitate comparison across studies, tests, and settings, and help to elucidate areas for future research and intervention.