Smoking as a risk factor for renal impairment and proteinuria: a case control study

ABSTRACT

In this study, the aim is to examine the association between current smoking status and indicators of kidney affection shown by reduced GFR and elevated urine protein/creatinine ratio in a population free of hypertension and diabetes mellitus, The study was carried out on 190 subjects [90 smokers and 100 non smokers]. Both smokers and non smokers were not diabetics nor hypertensives. For each subject serum creatinine [an indicator of GFR] and protein/creatinine ratio in urine [an indicator of proteinuria] were determined. Smokers were classified according to smoking index, which equals number of cigarettes smoked per day multiplied by the number of years of smoking, into mild smokers [smoking index <200], moderate smokers [smoking index 200-600] and heavy smokers [smoking index >600]. In our study, the socio-demographic characteristic of the study population were matched and there was no statistically significant difference between smokers and non smokers as regards residence, education, occupation and marital status. Males represent 95.6% and females represent 4.4% of the smokers while males represent 97% and females represent 3% of the non smokers. Smokers were more likely to have higher diastolic blood pressure and serum creatinine and lower GFR. In spite of the limited number of the study sample results pointed to the negative effect of smoking on kidney. There was a relation between smoking and renal impairment. A dose-response effect on GFR was shown with lifetime exposure to smoking. The relation between smoking and proteitnuria was less significant. However, one of the few females, who shared our study and was mild smoker, had been with proteinuria. This gives some relation between smoking and proteinuria especially in females. However. longitudinal studies with clear identification of abnormal glucose metabolism and hypertension will be required to provide the missing evidence for causality. The fact that smoking is an important renal risk factor trust be taken into consideration in the management of patients with renal disease. A concerted effort to encourage renal patients to give up smoking. Effective programs aimed at stroking prevention and cessation are highly needed