What is the prevalence of visual hallucinations in a first-episode psychosis population? A systematic review and meta-analysis of the literature

Background & Hypothesis
This systematic review and meta-analysis reviews the literature regarding the prevalence of visual hallucinations in patients with a first-episode psychosis. Previous reviews have focused on the prevalence of visual hallucinations in a general psychosis population, highlighting a weighted prevalence of 27% 1. 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. 2 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-analysed. 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; generalisability bias was the domain with the most risk of bias.

Study Results
Prevalence rates were synthesised 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.

Conclusion
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.