Long-acting injectables linked to fewer manic admissions in bipolar disorder

Design

Self-controlled case series using electronic health records, 2004–2023

Population

2,086 people with bipolar disorder given both injectable and oral antipsychotics, Hong Kong

Primary outcome

Healthcare use, relapse admissions and safety

Effect

Psychiatric admission aIRR 0.67 (0.61–0.74); manic 0.51 (0.44–0.59); EPS early 2.95 (1.40–6.22)

This American Journal of Psychiatry study, published on 9 September, used Hong Kong health records from 2004 to 2023. Among 17,841 people with bipolar disorder, 2,086 had periods on both long-acting injectable and oral antipsychotics. A self-controlled design compared each person with themselves, which removes fixed differences between patients such as illness severity or genetics.

Injectable periods were associated with fewer emergency visits (aIRR 0.85), all-cause admissions (0.79), psychiatric admissions (0.67), manic admissions (0.51) and mixed-episode admissions (0.31). Depressive-episode admissions did not differ significantly (1.34, confidence interval crossing 1), nor did cardiovascular admissions. Extrapyramidal symptoms were about three times as likely early on (aIRR 2.95) but not beyond 90 days.

Depots are often reserved in bipolar disorder for the most non-adherent patients. This supports raising them earlier with anyone whose relapses are mainly manic, while noting they did not protect against depressive relapse.

• Discuss a long-acting injectable with patients whose relapses are mainly manic or mixed.
• Do not expect protection against depressive relapse; that estimate did not favour injectables.
• Monitor closely for extrapyramidal symptoms in the first three months.
• Keep a mood stabiliser where indicated; this study compared antipsychotic formulations only.
• Cost and supply of depots vary in India; check availability before proposing a switch.

Why it matters

Depots are usually a last resort in bipolar disorder; this suggests they may earn an earlier place for mania-prone patients.

Don't overread it

This was observational; a self-controlled design limits but does not remove confounding by timing.

The statistics, in plain English

An incidence rate ratio of 0.51 means manic admissions happened at about half the rate during injectable periods compared with oral periods in the same people. The depressive-episode estimate (1.34, 0.94 to 1.93) crosses 1, so it could be no difference or some increase; it is not reassurance either way.

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