Assessing treatment adherence in psychiatry: a comparison of clinical judgment and therapeutic drug monitoring in acute care

Treatment adherence is the cornerstone of the management of psychiatric disorders in the prevention of acute symptom exacerbation, relapse, and hospitalization. Patients are usually treated with psychotropic polypharmacy, including complex regimens, which may contribute to nonadherence. In this real-world acute setting study, we used direct [therapeutic drug monitoring (TDM)] and indirect (emergency room and acute ward clinical judgments) measures to assess adherence in 145 patients with severe mental illnesses. Logistic regressions were used to predict adherence and agreement between adherence measures. The adherence estimates were predicted by sociodemographic and clinical factors and differed across methods: 24.8% for TDM, 55.9 and 50.4% for emergency room and acute ward clinical judgments, respectively. TDM aligned with clinical judgments in about 50% of cases, whereas the agreement between independent clinical judgments reached 84.9%. The concordance on adherence estimates between methods was influenced by sociodemographics, lifestyle, and clinical factors. Our findings underscore a discrepancy between different methods of adherence estimation. These methods capture distinct aspects of adherence and differ in their applicability and reliability, especially in acute settings. Future studies, integrating direct and indirect adherence estimates, are warranted to improve the accuracy of treatment adherence estimation for decision-making in managing exacerbation of psychiatric disorders.