Modeling human health behavior with a new index that measures connectivity.

Objective: Health behavior is an important determinant of health. Adherence to medication and abstinence from harmful substances are two critical health behaviors. Although conceptually related, both are assessed using disparate measures. The goal of this study was to develop and test a new index, gamma, which models health behavior by quantifying the connectedness of discrete incidents of health behavior. Study design and setting: We derive gamma from first principles and use it to reanalyze data from a published trial of treatment for alcohol use disorders. We model a primary endpoint, changes in binge drinking, using gamma and a traditional measure: change in number of monthly binges. The original trial was conducted in an urban hospital emergency department in the U.S. Results: Incorporating gamma into the model provided additional insights into the relationship between the intervention and long-term changes in drinking. Conclusion: Gamma provides an additional tool to model the effects of interventions on outcomes in trials of substance use interventions or medication adherence. Gamma measures the pattern of behavior and may increase the explanatory power of models assessing differences between various treatments. The gamma index offers the possibility of novel real-time interventions to promote healthy behaviors.