Exploring adherence to antidiabetic medications in Singapore primary care: a comparison of four models of proportion of days covered

The PDC models that incorporate prescribed data and use interval-based methods may result in more patients being classified as having poor adherence. Compared to the other models, we postulate that model P2 may provide the most accurate estimate of adherence, as it takes into account the prescribers' intent by including prescribed data and changes in medication regimens by using prescription-based method.