Background: Previous evidence has associated socioeconomic status and smoking.
Objective: To assess the association between socioeconomic status and smoking prevalence worldwide.
Methods: Systematic review and meta-analysis of observational studies (Mantel-Haenszel random-effects models) summarizing adjusted odds ratios (ORs) and 95% confidence intervals (CI). Heterogeneity was assessed by the I2 statistic. We performed subgroup analyses for continents, World Health Organization (WHO) regions, country mortality, gender, age, risk of bias and study decade. Independent reviewers selected studies, assessed potential bias and extracted data. We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), SocINDEX, African Index Medicus, and LILACS, and other sources for studies from 1989 to 2013 reporting direct measurements of income and current cigarette smoking. Funding: WHO.
Results: We retrieved 13,583 articles, included 201 and meta-analyzed 93. Median smoking prevalence: 17.8% (95% CI 3% to 70%). Lower income was associated with higher smoking prevalence. The direction of the association was consistent across all subgroups and was statistically significant for most of them (Table 1). Analyzing three categories of income, prevalence was highest in the lowest income levels compared to the middle, followed by the middle level compared to the highest either considering all studies or subgroups by gender and age group (Table 2).
Conclusions: Our results show that current cigarette smoking is significantly associated with lower income worldwide and across subgroups with a dose-response relationship.