Abstract
Background
There is converging evidence that youths at clinical high risk (CHR) are not only likely to develop the first episode of psychosis but also to develop poor physical outcomes. Some physical health risk factors - such as smoking - have been shown to increase the probability of a frank onset of psychosis in those at risk. A meta-analysis conducted in psychotic patients confirmed that daily tobacco use is associated with an increased risk of psychosis. A significant association between any attenuated psychotic symptoms (that characterize CHR state) and cigarette smoking has been recently shown in a study conducted in South London.
Nowadays, it is not completely clear how these findings would translate to the CHR population but a better understanding of how physical health parameters could affect psychopathological outcomes could be beneficial for these vulnerable clinical populations. To shed light on the percentage of smokers in CHR populations, an updated systematic review and meta-analysis of the literature has been carried out. Our main aim was to test whether the probability of being a smoker was higher in the CHR subjects or in the control group.
Methods
The literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We systematically scrutinized from literature inception to 2019 the following on-line databases: Web of Science Core Collection, BIOSIS Citation Index, KCL-Korean Journal Database, MEDLINE, Russian Science Citation Index, SCiELO Citation Index.
We have considered all the relevant studies reporting the smoking status in CHR subjects and in control groups.
We used the odds ratio (OR) as effect size measure and data were pooled using a random effect approach.
Results
Preliminary data show that CHR individuals were more likely to use tobacco that matched healthy controls. Specifically, the overall OR of 2.016 (p<.001 95%CI=1.476–2.749) indicated a higher likelihood that CHR individuals would use tobacco compared to controls. Heterogeneity was not significant (I²=30.193 p=0.11). The visual inspection of funnel plots did not reveal a clear suggestion for publication bias and the Egger’s test was non-significant (p=0.10).
Discussion
Our systematic review and meta-analysis suggest that is crucial to investigate physical health outcomes such as tobacco use as part of clinical practice in CHR services. Unfortunately, current CHR assessment tools are entirely based on the measurement of psychopathological features and do not include an assessment of these parameters on a regular basis.
Transition to psychosis in randomised clinical trials of individuals at clinical high risk of psychosis compared to observational cohorts: a systematic review and meta-analysis
