A US insurance-claims study found that medication coverage increased during the 6 months after adults with bipolar disorder switched to an aripiprazole injection given every 2 months. The analysis also found fewer hospital visits and lower reported medical costs in some groups.
Those findings are associations, not proof that the medication switch caused the changes. The study compared each person’s claims before and after switching, without a separate comparison group, and did not include symptom data.
What the study examined
The analysis included 1,467 people identified through bipolar disorder diagnosis codes who started aripiprazole 2-month ready-to-use, also called Ari 2MRTU or Abilify Asimtufii, between April 2023 and September 2024.
The injection is given every 56 days. Of the injections in the study, 83.8% were the 960-mg dose and 16.2% were the 720-mg dose.
Researchers divided participants into two groups. One included 371 people who had filled a daily oral antipsychotic during the previous year. The other included 1,096 people who had been receiving aripiprazole once-monthly, known as AOM or Abilify Maintena.
Participants had a mean age of about 39. Approximately 75% had commercial insurance and 25% had Medicaid. Substance use and anxiety disorders were common in both groups.
Medication coverage increased after the switch
Researchers used claims-based measures to estimate how much of the observation period was covered by antipsychotic treatment. In the pill-switch group, the proportion of days covered rose from 60% before the switch to 76% afterward. In the monthly-shot group, it rose from 56% to 81%.
Another measure, the medication possession ratio, increased from 0.67 to 0.85 in the pill-switch group and from 0.62 to 0.89 in the monthly-shot group. The share meeting the study’s adherence threshold rose from 41.2% to 72.0% among people switching from pills, and from 51.2% to 79.0% among those switching from the monthly injection.
Long-acting injectable antipsychotics release medication gradually from muscle tissue, reducing the need to remember a daily pill. However, coverage recorded in an insurance claim or injection record does not necessarily show how a person is feeling, whether symptoms are controlled, or whether every dose was taken as intended.
Hospital use and costs
The clearest reductions in hospital and emergency-care measures appeared in the pill-switch group. Average hospital days fell from 2.04 to 1.02 per person, while the share with any hospital stay declined from 26.4% to 14.3%. The average number of hospital admissions fell from 0.64 to 0.33 per person.
The share with an emergency-department visit fell from 36.4% to 24.3%. Outpatient visits also declined in this group, from 89.2% to 77.6%.
Among people switching from the monthly injection, hospital admissions fell from 0.21 to 0.13 per person and hospital days from 0.71 to 0.45. Any hospital stay changed from 10.2% to 7.0%, and any emergency-department visit from 20.0% to 17.3%; these changes were reported as not significant. Outpatient visits increased from 69.9% to 80.3%.
Reported all-cause medical costs also fell. In the pill-switch group, mean costs declined from $5,224.60 to $2,814.07 per patient per year. In the monthly-shot group, they declined from $2,670.09 to $1,770.84. These figures included inpatient, outpatient and emergency-department spending, but not pharmacy spending on the medicines.
Why the results need caution
The study used a before-and-after design with only 6 months of follow-up. Without a comparison group, the results cannot distinguish the effect of the switch from other changes over time.
People may have been switched during a difficult period and improved afterward for reasons unrelated to the injection, a possibility known as regression to the mean. Prescribers may also have selected particular patients for the 2-month formulation, while follow-up and extra clinical attention may have temporarily improved adherence.
The researchers described the analyses as descriptive and unadjusted. They did not account for other medicines, including mood stabilizers, and claims-based measures may overstate post-switch adherence. The diagnosis codes also covered bipolar II and unspecified bipolar disorder, although the study is discussed in the context of bipolar I disorder.
The work was funded by Otsuka and Lundbeck, which were involved in the study’s design, analysis, writing and decision to publish. Most authors worked for or consulted for those companies. Medicare patients and uninsured people were not included.
What other evidence suggests
In a 52-week randomized withdrawal trial involving 266 people with bipolar I disorder, mood episodes returned in 26.5% of those who remained on monthly aripiprazole versus 51.1% of those switched to placebo. The difference was driven mainly by fewer manic episodes.
In a separate 32-week trial involving 266 adults with schizophrenia or bipolar I disorder, the 2-month injection produced aripiprazole blood levels that matched the monthly shot, with similar rates of side effects.
A 2026 meta-analysis of 17 observational studies found lower relapse-related risk estimates for long-acting injectables than oral antipsychotics in some analyses. However, higher-quality studies did not show a significant advantage, and the certainty of evidence was rated low to very low.
What this means for patients
The findings support the need for more rigorous research on dosing schedules and long-acting injections, but they do not establish that switching to a 2-month injection will prevent relapse, hospitalization or costs for an individual.
Anyone considering a change in antipsychotic treatment should discuss the options, expected benefits, side effects and follow-up plan with a qualified clinician. The claims study cannot determine which treatment schedule is appropriate for a particular person.
AI tools were used to assist with the preparation of this article.
Leave a Reply