Smoking reduces lifespans and overall chances of kidney transplantation in dialysis patients

Dialysis patients who smoke are much less likely to receive a life-saving kidney transplant and much more likely to die sooner according to researchers from the Health Research Institute (HRI) at the University of Limerick and UL’s Graduate Entry Medical School (GEMS).

Professor Austin Stack MD, Lead Author and Consultant Nephrologist at UL Hospitals & Director of UL Health Research Institute (HRI)

The findings, which are published in a study appearing online in the journal BMC Nephrology, provide compelling evidence that smoking reduces overall life expectancy of dialysis patients as well as their overall chances of receiving a kidney transplant.

Approximately 2 million patients in the world are treated with dialysis every year. Kidney transplantation is by far the best option for most patients who develop kidney failure as it is associated with the best survival and quality of life.

Patients with kidney failure who are on dialysis have life spans that can be one-fifth that of the general population according to Professor Austin Stack MD, Lead author and Consultant Nephrologist at UL Hospitals & Director of UL Health Research Institute (HRI). It is hugely important that we identify those factors that affect overall patient survival and quality of life, especially factors that can potentially be modified to improve patient lives. Although previous studies have clearly shown that smoking is a major risk factor for death in the general population, few studies have evaluated the impact of smoking among patients who develop kidney failure.

In our study funded by the Health Research Board (HRB) and the Irish Heart Foundation (IHF), we assessed the impact of smoking among new dialysis patients and evaluated the extent to which it affected overall mortality rates and rates of kidney transplantation. Using data from the US Renal Registry, we followed 1,220, 000 patients, who began dialysis in the United States from 1995 to 2010, for an average for 2 years.

Among the major findings we found that:

• Smokers were significantly more likely to die than non-smokers and this adverse risk was equally present for both men and women
• Smoking had a far greater negative impact on the lifespans of younger men and women than among older patients
• Smoking was associated with higher death rates for all patients but the adverse impact was far greater for those with pre-existing cardiovascular conditions including coronary disease, stroke and peripheral vascular disease
• Smokers were significantly less likely to receive a kidney transplant than non-smokers and this adverse risk was equally present for both men and women
• Smokers with pre-existing cardiovascular conditions had the lowest risk of receiving a kidney transplant
• The relationship of smoking with higher death rates and lower kidney transplantation rates was not explained by concurrent illness, socioeconomic status, or differences in care provided to patients prior to or after initiating dialysis.

“Dialysis patients have extremely high premature death rates that are between 10- and 100-fold higher than in the general population, and smoking contributes substantially to lower patient survival,” said Professor Stack, senior author of the study, Consultant Nephrologist at University Hospital Limerick and Director of ULs Health Research Institute. “Smoking is a well-known risk factor for death and disability for patients in the general population. Our study, one of the largest ever conducted; found that smokers have alarmingly high rates of premature death. Quite strikingly, the risks of death were far greater in younger men and younger women than in older patients. Equally concerning, dialysis patients who smoked experienced lower rates of kidney transplantation and thus the opportunity to extend survival and quality of life. These risks were considerable in that smokers were between 26% and 50% less likely to receive a kidney transplant taking all other factors into consideration.

“Smoking is a major risk amplifier for all patients on dialysis” said Dr Stack. Consequently, we believe that kidney specialists and all healthcare providers should engage with their patients to pursue smoking cessation strategies at each and every opportunity”.