Smoking is associated with a high prevalence of microalbuminuria in hypertensive high-risk patients: data from I-SEARCH

Background Microalbuminuria (MAU) is a marker of endothelial dysfunction and a predictor of cardiovascular events. The effects of cigarette smoking on the prevalence of MAU in a high-risk population with arterial hypertension are unclear. Methods The International Survey Evaluating Microalbuminuria Routinely by Cardiologists in patients with Hypertension (I-SEARCH) documented the clinical profile of 20,364 patients with arterial hypertension and cardiovascular risk factors. In this population, 13,690 patients had no history of smoking, 4,057 patients were former smokers and 2,617 patients were current smokers. Results The prevalence of MAU was associated with the smoking status. Consumption of 1–20 cigarettes per day leads to an increase of 6.8% in the prevalence of MAU compared to non-smokers (P < 0.001). Smoking of >20 cigarettes per day was associated with a 12.5% higher prevalence of MAU compared to non-smokers, while former smokers had a 4.7% higher prevalence of MAU. Multivariable analysis revealed that smoking was independently associated with MAU [odds ratio (OR) smoking vs. non-smoking 1.16; 95% confidence interval (CI) 1.01–1.33; P < 0.05]. Particularly, a consumption of >20 cigarettes per day was associated with high odds for MAU (OR 1.33; CI 1.01–1.75; P < 0.05). Interestingly, independently of blood pressure, the use of an angiotensin receptor blocker and an ACE was associated with significantly reduced odds ratio for MAU in the smoking group, while there was no significant association in the non-smoking group. Conclusion The prevalence of MAU in hypertensive patients is higher in smokers than in non-smokers with a strong dose dependency.