Smoking as a risk factor for diabetic nephropathy: a meta-analysis.

BACKGROUND

Previous studies have investigated the connection between diabetic nephropathy and smoking, and reported widely varying rates. This study aimed to systematically analyze the impact of smoking on diabetic nephropathy.

METHODS

We searched the PubMed and EMBASE electronic databases to identify relevant English-language studies published up to March 2016. Eligible studies were selected using inclusion and exclusion criteria. Data for each study were extracted independently by two authors. The homogeneity of the effect size across the studies was tested. Odds ratio (OR) was calculated by using the random-effect model. Sensitivity analysis was performed to reduce heterogeneity, and publication biases were examined.

RESULTS

A total of 21 eligible studies were selected and pooled analyzed. No significant differences in demographic characteristics were found between patients with diabetic nephropathy and those with non-diabetic nephropathy. Significant heterogeneity across studies was found except those of diabetes mellitus controls. The aggregate OR of smoking in the patients with diabetic nephropathy in comparison with those with non-diabetic nephropathy was 1.70 (95% confidence interval 1.48-1.95). No evidence of publication bias was found.

CONCLUSION

Our findings indicate that smoking is a significant risk factor for diabetic nephropathy in diabetic patients.