What individuals do (or do not do) when they get sick: A review of theoretical frameworks of illness behavior and their application in empirical research

Background: Decision making in the event of sickness has a major influence on people's lives. Moreover, patients' decisions about healthcare fundamentally determine the performance of the overall healthcare system in terms of a population's health, the quality of healthcare services, and the level of expenditures. Understanding what individuals do or do not do when they experience physical or mental symptoms of illness has therefore been a key topic in medical sociology and health psychology alike. In both disciplines, several prominent models of illness behavior have been developed and used in empirical analysis. Despite the large body of theoretical and empirical research, the debate about the “best” theoretical framework continues. Method: We review the key conceptual components of six models of illness behavior: the Health Belief Model, the Protection Motivation Theory, the Theory of Planned Behavior, the Common-Sense Model of Self-Regulation, Andersen's Behavioral Model of Health Service Use, and the Network-Episode Model. Moreover, we present a systematic review of systematic reviews and meta-analysis based on these models. We discuss the similarities and differences of how these models are operationalized and utilized in empirical research. Results: We show that the models fulfil different purposes by shedding light on different dimensions of illness behavior, e.g., preventive health behavior or the utilization of healthcare services in the event of illness symptoms. We provide a guide for authors how to select a well-suited model and how to assess the strengths but also the limitations of the chosen theoretical approach. Discussion: Such a knowledgeable application of each model can help to move research on illness behavior forward rather than the never-ending search of an “integrative framework of illness behavior”.