Smoking in male patients with schizophrenia in China: A meta-analysis

Background: The aim of this study was to examine the prevalence of current smoking in male patients with schizophrenia in China.

Method: A systematic literature search was conducted from database inception until June 20, 2015 without language restrictions in PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and WanFang Database. Studies fulfilling the following criteria were included: (a) data available in male schizophrenia patients and (b) data available on current smoking status. Statistical analyses were performed with the Comprehensive Meta-Analysis program.

Results: A total of 23 studies met eligibility criteria for the meta-analysis. The pooled prevalence of current smoking was 59.1% (95% Confidence interval [CI]: 53.3-64.7%). Current smoking was significantly more frequent in inpatients than in outpatients (61.3% vs. 48.2%, Q=7.5, P=0.006), and higher in chronic compared to first-episode patients (74.5% vs. 45.1%, Q=32.3, P=0.0001). Furthermore, using a median split, patients aged 38.2 years or older smoked more often than those aged below 38.2 years (65.8% vs. 52.3%, Q=6.4, P=0.01). There were no significant associations between prevalence of current smoking and definitions of smoking, study publication year, sample size and illness duration.

Conclusions: The pooled prevalence of current smoking of male patients with schizophrenia in China is lower compared to Western and other Asian countries. Possible relationships between lower prevalence of current smoking and psychopathology in patients with schizophrenia require further investigation.