Association between smoking and chronic kidney disease: a case control study

Background: The progression of chronic kidney disease (CKD) remains one of the main challenges in clinical nephrology. Therefore, identifying the pathophysiological mechanisms and the independent preventable risk factors helps in decreasing the number of patients suffering end stage renal disease and slowing its progression. Methods: Smoking data was analyzed in patients with CKD throughout 2005-2009. One hundred and ninety-eight patients who had recently been diagnosed with stage three CKD or higher according to the National Kidney Foundation (NKF) 2002 Classification were studied. The control group was randomly selected and then matched with the case subjects using a computerized randomization technique. The relative risk was estimated by computing odds ratio (OR) by using multinomial logistic regression in SPSS (R) for Windows between the two groups. Results: Smoking significantly increases the risk of CKD (OR = 1.6, p = 0.009, 95% CI = 1.12-2.29). When compared to nonsmokers, current smokers have an increased risk of having CKD (OR = 1.63 p = 0.02, 95% CI = 1.08-2.45), while former smokers did not have a statistically significant difference. The risk increased with high cumulative quantity (OR among smokers with > 30 pack-years was 2.6, p = 0.00, 95% CI = 1.53-4.41). Smoking increased the risk of CKD the most for those classified as hypertensive nephropathy (OR = 2.85, p = 0.01, 95% CI = 1.27-6.39) and diabetic nephropathy (2.24, p = 0.005, 95% CI = 1.27-3.96). No statistically significant difference in risk was found for glomerulonephritis patients or any other causes. Conclusion: This study suggests that heavy cigarette smoking increases the risk of CKD overall and particularly for CKD classified as hypertensive nephropathy and diabetic nephropathy.