OBJECTIVES

Long-acting injectable (LAI) antipsychotics (APs) include first- and second-generation LAI APs. Each of LAI APs has an oral equivalent formulation and aripiprazole, olanzapine, ziprasidone also have a short-acting injectable (SAI) equivalent formulations. The study objective was to determine inpatient prescribing patterns of LAI APs and their oral/SAI formulations.

METHODS

Health Facts® database (Cerner Corp., Kansas City, MO) was used to examine prescribing patterns of APs and all-cause hospital admissions for patients diagnosed with schizophrenia, schizoaffective disorders, or bipolar disorder from 2010 to 2016. The unit of analysis was an inpatient hospital stay or emergency department visit during which at least one AP was administered. Hospital admissions were divided into one of 15 mutually exclusive categories of medication class using two classification methods. The difference between the two classification methods was whether SAIs were included. Pooled and year-specific utilization rates for each medication class category were calculated. Annual class-specific rates were plotted on bar graphs. Chi-square tests for each class category across years were performed.

RESULTS

Using the first classification method, 50,686 encounters were identified; and using the second classification method, 94,989 encounters were identified. Oral formulations of second-generation LAI APs (n=32,311, 64%), and Oral/SAI formulations of second-generation LAI APs (n=38,621, 41%) were two primary medication class categories under two classification methods, respectively. There were 494 encounters (<1% under both classification methods) where only the first-generation LAI APs were prescribed, and 553 encounters (<1.1% under both classification methods) where only the second-generation APs were prescribed. Most chi-square tests for each class category across years were statistically significant (P<0.05).

CONCLUSIONS

Compared with their oral or SAI formulations, LAI APs were underutilized. Future research is needed to examine the effect of the underutilization on patients’ health outcomes.