3A-06 - Comparison of oral and long-acting injectable antipsychotics on disease relapses and healthcare utilizations in bipolar disorder: a 20-year follow-up study

Background: Long-acting injectable antipsychotics (LAIAs), despite their advantage in improving adherence, are generally reserved for the most severe cases of bipolar disorder. Evidence comparing the safety and effectiveness of LAIAs to oral antipsychotics (OAs) remains limited in bipolar disorder, particularly among Asian populations. This lack of data may hinder healthcare providers and patients from recognizing the broader benefits of LAIAs.

Objectives: This study aims to compare the risk of disease relapses and healthcare utilizations between LAIAs and OAs among individuals with bipolar disorder in Hong Kong.

Methods: Individuals diagnosed with bipolar disorder (ICD-9-CM codes: 296.0, 296.1, 296.4–296.8) and prescribed both LAIAs and OAs between January 1, 2004, and December 31, 2023, were identified from the Clinical Database Analysis and Reporting System of the Hong Kong Hospital Authority. Individuals with outcomes related to disease relapses and healthcare utilizations were included in a self-controlled case series study. The conditional Poisson regression model was used to calculate the adjusted incidence rate ratios (IRRs) during LAIA treatment compared to OA treatment. This model minimized time-invariant confounding and accounted for time-varying factors associated with antipsychotic use and the investigated outcomes, including age, season, covid-19 stringency index, and the use of concomitant drugs.

Results: Of the 17,841 individuals diagnosed with bipolar disorder, 2,086 (11.7%) were prescribed both LAIAs and OAs. Compared with OAs, LAIAs were associated with a lower risk of hospitalizations for psychiatric disorders (n=1,723; IRR = 0.67 [95%CI 0.61-0.74]), hospitalizations for manic episodes (n=1,244; IRR = 0.51 [0.44-0.59]), all-cause hospitalizations (n=1,881; IRR = 0.79 [0.73-0.85]), and all-cause emergency department visits (n=1,912; IRR = 0.85 [0.81-0.89]). No significant difference was observed in hospitalizations for depressive episodes (n=320; IRR =1.34 [0.94-1.93]). Similar associations persisted during subsequent treatment periods (beyond the first 90 days).

Conclusions: LAIAs were associated with reduced disease relapses and healthcare utilizations, including a lower risk of hospitalizations for psychiatric disorders, hospitalizations for manic episodes, all-cause hospitalizations and emergency department visits among individuals with bipolar disorder. These findings suggest that LAIAs may enhance clinical outcomes for bipolar disorder.