The Effect Of Smoking On Renal Function Decline And Proteinuria In Rural Hypertensive Population Residing In Eastern China

Objective To investigate the effect of smoking on renal function decline in rural hypertensive population residing in Eastern China, and provide a preliminary basis for early prevention of chronic kidney disease.Methods In our study, 20702 subjects with hypertension aged 45-75 years old were enrolled from Anqing, Anhui province and Lianyungang, Jiangsu province during May 2008 to July 2009. Cigarette smoking was collected by standardized questionnaire; Renal function was estimated by glomerular filtration rate(e GFR) using the CKD-EPI formula. Proteinuria was diagnosed by the dipstick test, and results of 1+ or higher in dipstick test were regarded as abnormal.Results A total of 20312 participants(60.0±7.5 years of age) were the final subjects in the study. The total smoking rate was 31%, male smoking rate was 69.3%, and 4.6% for female. Renal function decline(e GFR <60 ml/min/1.73m2) in patients with a total of 427 people, accounting for 2.1% of the study population. Wherein urine protein qualitative test for detection of 19594 people, a total of 1152 patients with proteinuria(5.9%). Glomerular filtration rate(94.3 ± 13.0, ml/min/1.73m2) in never smokers was higher than former smokers(90.2 ± 14.0, ml/min/1.73m2) and current smokers(92.0 ± 13.4, ml/ min/1.73m2), differences between the groups was P<0.001. The prevalence of proteinuria was 6.5% in former smokers and 6.0% in current smokers were higher than the 5.5% in never smokers, but the prevalence of proteinuria among smoking group had no significant difference(P=0.481). Logistic regression analysis showed that compared with never smokers, the prevalence of renal function decline was significantly higher in current smokers(2.5% versus 1.8%, OR=1.42, 95%CI: 1.05~1.92, P=0.022) and former smokers(3.6% versus 1.8%, OR=1.50, 95%CI: 1.04~2.17, P=0.030) after adjusting for study center, gender, age, body mass index, blood pressure, serum lipids, history of diabetes mellitus, taking antihypertensive drugs and alcohol consumption. However, current smokers(OR=0.98, 95% CI: 0.75~1.27, P=0.852), former smokers(OR = 0.97, 95%CI: 0.80~1.18, P=0.790) compared with never smokers, the prevalence of proteinuria had no statistically significant in the different smoking status. Among the different stratification of gender, age, region and taking antihypertensive drugs, smoking status and renal function decline had no significant relationships(interaction P values were greater than 0.10). However, cigarette smoking and elevated blood pressure(systolic blood pressure ≥160 mm Hg versus < 160 mm Hg, P value for interaction was 0.006) had a synergistic effect in prevalence of renal function decline. But diastolic blood pressure between groups had no statistically significant(≥100 versus <100 mm Hg, interaction P = 0.853).Conclusion Cigarette smoking(both current and former smokers) was significantly associated with the renal function decline in hypertensive patients. Elevated blood pressure levels and smoking had a synergistic effect in prevalence of renal function decline. It prompted that smokers who had a more stringent blood pressure control could reduce the early injury of renal target organs. There was no significant association between smoking status and proteinuria.