Continuous D2 Blockade in First-Episode Schizophrenia Does Not Raise Relapse Risk
More than 5 years of continuous treatment with dopamine D2 receptor-blocking long-acting injectable (LAI) antipsychotics does not appear to increase the risk of breakthrough psychosis in patients with first-episode schizophrenia, according to study findings published in the American Journal of Psychiatry.
“About 40% to 50% of patients with first-episode schizophrenia will relapse despite continuous D2 blockade, apparently due to non-dopaminergic elements of the pathophysiology of the illness, as the results show that long-term dopamine receptor blockade is not associated with an increased risk of breakthrough psychosis,” wrote corresponding author Jari Tiihonen, MD, PhD, of the University of Eastern Finland, Kuopio, Finland, and study coauthors.
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Researchers came to this conclusion after investigating incidence rates of severe relapse necessitating hospitalization in 305 patients with first-episode schizophrenia in Finland who were continuously treated with LAI antipsychotics. Over a 10-year follow-up, the cumulative probability of relapse among patients was 45%, the study found.
The research team had hypothesized that the incidence of breakthrough psychosis would be accelerated with continuous D2 antagonist treatment longer than 5 years. However, the annual relapse incidence per person-year decreased from 0.26 over the first year to 0.05 during the fifth year. The corresponding incidence rate ratio (IRR) of relapse during years 2 through 10, using year 1 as the reference, was 0.18, according to the study.
“During years 6–10, only 4 relapses occurred during 128 person-years,” researchers wrote, “corresponding to an IRR of 0.12 (95% CI=0.03–0.33) compared with year 1.”
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