Presentation (CTI)

OBJECTIVES: Bipolar disorder, a severe recurrent psychiatric condition, affects nearly 46 million people globally, with an estimated 2.8% of U.S. adults affected in 2024. Treatment adherence is critical, requiring appropriate metrics. Proportion of Days Covered (PDC) is a quantitative medication adherence measure, calculated as the proportion of days a patient has access to prescribed medication within a specified period. This study aimed to estimate PDC within 180 days after the first medication fill using two assumption scenarios.
METHODS: Two PDC metrics based on distinct assumptions were used to estimate adherence in real-world healthcare data. PDC1 assumes patients start medication on the fill day, refill before exhausting current supply, and discard remaining medication from previous fills. PDC2 assumes patients start medication on the fill day, refill before exhausting current supply, and complete all pills from the existing prescription before starting the new one.
RESULTS: The dataset included bipolar disorder patients taking second-generation atypical antipsychotics (SGAntipsy, 150,402) following PDC1 and first-generation typical antipsychotics (FGTAntipsy, 100,362) following PDC2. The PDC was 0.82[95% CI:0.65-0.99] for SGAntipsy and 0.78[95% CI:0.62-0.94] for FGTAntipsy.
CONCLUSIONS: These algorithms enable the evaluation of pharmacy services and patients’ adherence in real-world databases, despite temporary data gaps from switching suppliers. Accurately identifying adherence issues enhances patient experience, improves outcomes, and reduces medication wastage. This study showed that patients are more adherent to SGAntipsy.