Differences in associations between long-acting injectable and oral antipsychotic prescribing and healthcare utilisation in people with intellectual disability: a self-controlled case series (LOID study).

backgroundLiterature guiding the use of long-acting injectable antipsychotics (LAIAs) versus oral antipsychotics (OAs) in people with intellectual disability (PWID) remains scarce.

objectiveExamining the associations of LAIAs vs OAs with healthcare utilisation among PWID.

methodsThis self-controlled case series study used electronic health records from Hong Kong. We included adults with intellectual disability prescribed both LAIAs and OAs at different periods in 2004-2023. We compared within-individual LAIA and OA periods, adjusting for age, calendar year, season, inpatient stay and concomitant psychotropic use, using conditional Poisson regression to estimate incidence rate ratios (IRRs) for all-cause emergency department (ED) visits; all-cause hospitalisations; hospitalisations for psychiatric disorders, schizophrenia/bipolar disorder, behaviour-related problems, somatic disorders and cardiovascular diseases (CVDs) and diagnosis records of extrapyramidal symptoms (EPS); falls and fractures. Subgroup analyses were conducted by diagnosis of schizophrenia or bipolar disorder.

findingsWe identified 1675 PWID who had been prescribed both OAs and LAIAs at different periods during the study period. LAIA use was associated with lower risks of incident all-cause ED visits (adjusted IRR: 0.71, 95% CI 0.51 to 0.98), all-cause hospitalisations (0.91, 0.85-0.98); hospitalisations for psychiatric disorders (0.90, 0.81-0.99); for schizophrenia/bipolar disorder (0.86, 0.75-0.99) and EPS (0.34, 0.23-0.51), compared with OAs. In PWID with schizophrenia/bipolar disorder, LAIAs were associated with lower risks of all-cause hospitalisations, hospitalisations for psychiatric disorders, schizophrenia/bipolar disorder, behaviour-related problems and somatic disorders, and EPS, but a higher risk of hospitalisations for CVDs (with hypertensive disease being the most common), compared with OAs. In contrast, among PWID without such diagnoses, LAIA use was associated with higher risks of all-cause hospitalisations, hospitalisations for somatic disorders; a lower risk of incident all-cause ED visits and hospitalisations for CVDs, but no significant difference in hospitalisations for behaviour-related problems, compared with OAs.

conclusionsThese findings are consistent with potential benefit of LAIAs among PWID with schizophrenia or bipolar disorder, while raising concern about off-label use in those without these diagnoses. CLINICAL IMPLICATIONS: LAIAs may be considered in PWID with schizophrenia or bipolar disorder; off-label use in those without these diagnoses should be approached cautiously, and deprescribing may be considered where appropriate if these results are replicated.