Dataset Information

Does tobacco use cause psychosis? Systematic review and meta-analysis.

ABSTRACT:

Background

Although the association between psychotic illness and cigarette smoking is well known, the reasons are unclear why people with psychosis are more likely to smoke than are the general population. We aimed to test several hypotheses. First, that daily tobacco use is associated with an increased risk of psychotic illness in both case-control and prospective studies. Second, that smoking is associated with an earlier age at onset of psychotic illness. Finally, that an earlier age at initiation of smoking is associated with an increased risk of psychosis. We also aimed to derive an estimate of the prevalence of smoking in patients presenting with their first episode of psychosis.

Methods

We searched Embase, Medline, and PsycINFO and selected observational studies in which rates of smoking were reported in people with psychotic disorders, compared with controls. We calculated the weighted mean difference for age at onset of psychosis and age at initiation of smoking. For categorical outcomes, we calculated odds ratios from cross-sectional studies and risk ratios from prospective studies.

Findings

Of 3717 citations retrieved, 61 studies comprising 72 samples met inclusion criteria. The overall sample included 14 555 tobacco users and 273 162 non-users. The prevalence of smoking in patients presenting with their first episode of psychosis was 0·57 (95% CI 0·52-0·62; p<0·0001). In case-control studies, the overall odds ratio for the first episode of psychosis in smokers versus non-smokers was 3·22 (95% CI 1·63-6·33), with some evidence of publication bias (Egger's test p=0·018, Begg's test p=0·007). For prospective studies, we calculated an overall relative risk of new psychotic disorders in daily smokers versus non-smokers of 2·18 (95% CI 1·23-3·85). Daily smokers developed psychotic illness at an earlier age than did non-smokers (weighted mean difference -1·04 years, 95% CI -1·82 to -0·26). Those with psychosis started smoking at a non-significantly earlier age than did healthy controls (-0·44 years, 95% CI -1·21 to 0·34).

Interpretation

Daily tobacco use is associated with increased risk of psychosis and an earlier age at onset of psychotic illness. The possibility of a causal link between tobacco use and psychosis merits further examination.

Funding

NIHR Maudsley Biomedical Research Centre.

SUBMITTER: Gurillo P

PROVIDER: S-EPMC4698800 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:To examine the risk of treatment emergent, cardiovascular serious adverse events associated with varenicline use for tobacco cessation.Meta-analysis comparing study effects using four summary estimates.Medline, Cochrane Library, online clinical trials registries, and reference lists of identified articles.We included randomised controlled trials of current tobacco users of adult age comparing use of varenicline with an inactive control and reporting adverse events. We defined treatment emergent, cardiovascular serious adverse events as occurring during drug treatment or within 30 days of discontinuation, and included any ischaemic or arrhythmic adverse cardiovascular event (myocardial infarction, unstable angina, coronary revascularisation, coronary artery disease, arrhythmias, transient ischaemic attacks, stroke, sudden death or cardiovascular related death, or congestive heart failure).We identified 22 trials; all were double blinded and placebo controlled; two included participants with active cardiovascular disease and 11 enrolled participants with a history of cardiovascular disease. Rates of treatment emergent, cardiovascular serious adverse events were 0.63% (34/5431) in the varenicline groups and 0.47% (18/3801) in the placebo groups. The summary estimate for the risk difference, 0.27% (95% confidence interval -0.10 to 0.63; P = 0.15), based on all 22 trials, was neither clinically nor statistically significant. For comparison, the relative risk (1.40, 0.82 to 2.39; P = 0.22), Mantel-Haenszel odds ratio (1.41, 0.82 to 2.42; P = 0.22), and Peto odds ratio (1.58, 0.90 to 2.76; P = 0.11), all based on 14 trials with at least one event, also indicated a non-significant difference between varenicline and placebo groups.This meta--analysis--which included all trials published to date, focused on events occurring during drug exposure, and analysed findings using four summary estimates-found no significant increase in cardiovascular serious adverse events associated with varenicline use. For rare outcomes, summary estimates based on absolute effects are recommended and estimates based on the Peto odds ratio should be avoided.

Project description:ImportanceThis systematic review and meta-analysis is, to date, the first and most comprehensive to focus on the incidence of nonaffective psychoses among refugees.ObjectiveTo assess the relative risk (RR) of incidence of nonaffective psychosis in refugees compared with the RR in the native population and nonrefugee migrants.Data sourcesPubMed, PsycINFO, and Embase databases were searched for studies from January 1, 1977, to March 8, 2018, with no language restrictions (PROSPERO registration No. CRD42018106740).Study selectionStudies conducted in Denmark, Sweden, Norway, and Canada were selected by multiple independent reviewers. Inclusion criteria were (1) observation of refugee history in participants, (2) assessment of effect size and spread, (3) adjustment for sex, (4) definition of nonaffective psychosis according to standardized operationalized criteria, and (5) comparators were either nonrefugee migrants or the native population. Studies observing ethnic background only, with no explicit definition of refugee status, were excluded.Data extraction and synthesisThe Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed for extracting data and assessing data quality and validity as well as risk of bias of included studies. A random-effects model was created to pool the effect sizes of included studies.Main outcomes and measuresThe primary outcome, formulated before data collection, was the pooled RR in refugees compared with the nonrefugee population.ResultsOf the 4358 screened articles, 9 studies (0.2%) involving 540 000 refugees in Denmark, Sweden, Norway, and Canada were included in the analyses. The RR for nonaffective psychoses in refugees was 1.43 (95% CI, 1.00-2.05; I2 = 96.3%) compared with nonrefugee migrants. Analyses that were restricted to studies with low risk of bias had an RR of 1.39 (95% CI, 1.23-1.58; I2 = 0.0%) for refugees compared with nonrefugee migrants, 2.41 (95% CI, 1.51-3.85; I2 = 96.3%) for refugees compared with the native population, and 1.92 (95% CI, 1.02-3.62; I2 = 97.0%) for nonrefugee migrants compared with the native group. Exclusion of studies that defined refugee status not individually but only by country of origin resulted in an RR of 2.24 (95% CI, 1.12-4.49; I2 = 96.8%) for refugees compared with nonrefugee migrants and an RR of 3.26 (95% CI, 1.87-5.70; I2 = 97.6%) for refugees compared with the native group. In general, the RR of nonaffective psychosis was increased in refugees and nonrefugee migrants compared with the native population.Conclusions and relevanceRefugee experience appeared to be an independent risk factor in developing nonaffective psychosis among refugees in Denmark, Sweden, Norway, and Canada. These findings suggest that applying the conclusions to non-Scandinavian countries should include a consideration of the characteristics of the native society and its specific interaction with the refugee population.

Project description:ObjectiveTo evaluate what is known about active tobacco use during pregnancy and the association with infant respiratory health.DesignSystematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Data sourcesMEDLINE, EMBASE, Cochrane, CINAHL, and Maternity and Infant Care were searched thoroughly until June 2020.Eligibility criteria for selecting studiesWe included case-control and cohort studies estimating the association between active tobacco use during pregnancy and infant respiratory health (wheezing and apnoea) and lung function parameters in the first 12 months of life.Data extraction and synthesisExtraction and risk of bias assessment were conducted by two independent reviewers. The odds ratio, relative risk and mean differences were pooled with a 95% CI using the generic inverse variance method. Heterogeneity was assessed and expressed by percentage using I2.ResultsWe identified 4423 abstracts, and 21 publications met the eligibility criteria. Pooled OR showed an increase in wheezing episodes in infants born to mothers who were active tobacco users during pregnancy (OR 1.50, 95% CI 1.27 to 1.77, p<0.01). Mixed results were found on lung function parameters, and a meta-analysis including two studies with comparable methodology showed a trend towards reduced maximum flow rate at functional residual capacity of -34.59 mL/s (95% CI -72.81 to 3.63, p=0.08) in 1-month-old infants born to women who smoked during pregnancy. A higher risk of apnoea was described for infants born to mothers who used smokeless tobacco during pregnancy, while the results in infants born to women who actively smoked tobacco during pregnancy were non-conclusive.ConclusionInfants born to mothers who actively smoked during pregnancy are at higher odds of having wheeze and may have lower lung function. Smokeless tobacco use in pregnancy may increase the risk of apnoea in infancy.Prospero registration numberCRD42018083936.