Smoking increases the risk for developing renal failure, according to a new study.
Among individuals younger than 70 years, current smokers and former smokers are at 3.3 times and 4.0 times increased risk of renal failure compared with individuals who never smoked, after adjusting for confounders, investigators reported in Kidney International (2011;80:516-523). Among individuals aged 70 years and older, current or former smoking was not at increased risk of renal failure.
Compared with men who never smoked, men who currently smoked and who used to smoke had a 3.7 times and 5.7 times increased risk of renal failure. The researchers, Stein I. Hallan, MD, of St. Olav University Hospital in Trondheim, Norway, and Stephen R. Orth, MD, of the University of Regensburg in Regensburg, Germany, observed no significant association between current or former smoking and renal failure in women.
In addition, compared with women who never smoked, men who currently smoked or used to smoke were at 4.3 times and 6.6 times increased risk of renal failure. Again, the study showed no significant association between smoking and renal failure risk in women.
The findings came to light from a study of 65,589 individuals who participated in the HUNT II study, a Norwegian general health survey. During a median follow-up of 10.3 years, 124 subjects progressed to stage 5 chronic kidney disease.
The study showed that, among men younger than 70 years who used to smoke, the risk of renal failure diminished with time since smoking cessation. For example, compared with men who never smoked, men who stopped smoking one to four years earlier had a 21.5 times increased risk of renal failure. However, men who had stopped smoking 20 years earlier or more had a 10.5 times increased risk.
In addition, the researchers observed that the risk of renal failure increased with the number of pack-years among men younger than 70. Compared with not smoking, 1-9, 10-19, 20-39, and 40 or more pack-years of smoking was associated with a 4.2, 8.8, 13.5, and 38 times increased risk of renal failure.
The authors concluded that “all CKD patients should now be very strongly encouraged to quite smoking, and if necessary given psychological and/or pharmacological support to achieve this very important goal. In this context, our finding of a progressive disease in renal risk with increasing time since smoking cessation is very encouraging.”