Compared with oral antipsychotics (OAPs), long-acting injectable antipsychotics (LAIs) should improve medication adherence and reduce relapses in schizophrenia. However, meta-analyses of randomized trials and mirror-image studies yielded inconsistent results. Nonrandomized cohort studies with parallel comparisons of LAIs and OAPs offer a third design to examine this issue. We meta-analyzed cohort studies with ≥24 weeks duration and hospitalization data. Primary outcome was hospitalization rate, ie, number of hospitalizations per person-year. Secondary outcomes included hospitalization risk, ie, proportion of patients experiencing ≥1 hospitalizations, all-cause discontinuation, and total hospitalization days. Patient severity and/or chronicity at baseline was also meta-analyzed and explored as a potential effect size moderator. Altogether, 42 studies (n = 101 624; follow-up = 18.6 ± 10.0 mo) were meta-analyzed. LAIs were superior to OAPs regarding hospitalization rate (studies = 15, person-years = 68 009, rate ratio = 0.85, 95% CI = 0.78-0.93, P < .001) and all-cause discontinuations (studies = 10, n = 37 293, risk ratio = 0.78, 95% CI = 0.67-0.91, P = .001), but not regarding hospitalization risk (studies = 33, n = 51 733, risk ratio = 0.92, 95% CI = 0.84-1.00, P = .06), and hospitalization days (studies = 11, n = 21 328, Hedges' g = -0.05, 95% CI = -0.16 to 0.06, P = .39). Illness severity/chronicity was significantly greater in patients prescribed LAIs vs OAPs when all available information was pooled together (studies = 23, n = 61 806, Hedges' g = 0.15, 95% CI = 0.03-0.26, P = .01), but not when examined separately. In summary, this metaanalysis of cohort studies, which included patients that are broadly representative of clinical practice, indicates that LAIs are superior to OAPs. The lack of significant superiority of LAIs for hospitalization risk and hospital days needs to be interpreted in the context of naturalistic treatment selection with subsequently greater illness severity/chronicity in LAI-treated patients.
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