Smoking as a risk factor for physical impairment: a systematic review and meta-analysis of 18 cohort studies.

Smoking has various negative effects on diseases and disabilities. The authors examined the relationships between smoking and physical impairments in this meta-analysis. Two databases including PubMed, Scopus, and two gray literature databases including Google Scholar and Research Gate were searched systematically using Mesh keywords. After reviewing the studies, 18 Prospective cohort studies were selected based on criteria. Risk Ratio (RR) of physical impairment as outcome of smoking and subgroup analysis based on gender, adjusted quality, geographic location and smoking status were done using random effects. Publication bias was calculated as well. The results showed that the risk of physical impairment in smokers is equal to RR = 1.26 and CI = 1.16-1.36 ( = <001). In women, RR = 1.19 and CI = 0.80-1.75 ( = 0.388); and in men, RR = 1.87 and CI = 1.31-2.68 ( = <001) were achieved. Some evidences of publication bias were found. Smoking increases the risk of physical impairment. Men are at a greater risk of physical impairment; perhaps because the prevalence of smoking in men is higher than women.