What Is the Prevalence of Visual Hallucinations in a First-Episode Psychosis Population? A Systematic Review and Meta-analysis of the Literature.

Background and Hypothesis: This systematic review and meta-analysis review the literature regarding the prevalence of visual hallucinations in patients with first-episode psychosis. Previous reviews have focused on the prevalence of visual hallucinations in a general psychosis population, highlighting a weighted prevalence of 27%. However, no reviews have focused specifically on the experiences of those with a first episode of psychosis. Understanding "first-episode" experiences is crucial, as intervention during this "critical period" is thought to define long-term outcome. Therefore, it is important that the prevalence of different symptoms during this period is accurately represented. Study Design: Systematic searches yielded 15 studies to be meta-analyzed. Information to calculate event rates was extracted. Studies were rated for their methodological quality using a risk of bias tool. The quality of included studies varied; generalizability bias was the domain with the most risk of bias. Study Results: Prevalence rates were synthesized from the 15 papers included in the final analysis, which generated a weighted prevalence estimate of 33% of people with first-episode psychosis experiencing visual hallucinations. Subgroup analyses were carried out and did not demonstrate significant associations. Conclusions: This meta-analysis provides a robust estimate of 33% for the prevalence of visual hallucinations in first-episode psychosis; highlighting that visual hallucinations are relatively common experiences.