Applying comparative effectiveness research methods in bipolar disorders.

Background: Randomized clinical trials [RCT] are the Gold Standard of medical evidence. However, observational comparative effectiveness research [CER] based on real-world data is receiving national attention. This paper demonstrates how observational CER can fill important gaps in clinical knowledge left behind by RCT approaches. An example of CER in bipolar disorders is presented.

Methods: Paid claims data from a large commercial insurer were used to identify episodes of drug therapy. Episodes were defined each time a patient initiated or restarted therapy using an antipsychotic, antidepressant or mood stabilizing medication. Episode definitions were based on calculations of continuous days of drug therapy using a 15 day gap definition. 105,440 episodes of drug therapy were included in the analysis.

Results: Most episodes were initiated using a mood stabilizing drug (40%) or an antidepressant (40%). Over 59% of all episodes were for augmentation therapy, followed by switching episodes (25%) and restart episodes (16%). Patient outcomes measured by either duration of uninterrupted therapy or one-year post-treatment cost varied significantly with patient treatment history, especially episode type. The comparative effectiveness of alternative therapies was sensitive to the extent to which treatment history is taken into account.

Conclusions: Observational research can evaluate patient outcomes across a wide range of clinical presentations with regard to the patient's treatment history. Treatment history is a major determinant of patient compliance and future treatment costs. Failure to account for treatment history can introduce bias into comparative effectiveness results. Observational CER research can also uncover important questions that require future research.