Cigarette smoking — a universal health hazard — may particularly damage kidney function in African-Americans, according to new research in the Journal of the American Heart Association.
“Cardiovascular and kidney diseases are closely linked, but few people are aware of the impact of smoking on kidney function,” said Michael Hall, M.D., study lead author and an assistant professor of medicine at the University of Mississippi Medical Center in Jackson.
Researchers determined rates of decline in kidney function in 3,648 African-Americans in the Jackson Heart Study, which examines cardiovascular disease in African-Americans ages 21-84 in the Jackson, Mississippi, area. Participants completed three questionnaires over 12 years.
After adjusting for factors such as age, gender, physical activity, diabetes, hypertension and prevalent cardiovascular disease, researchers found:
Kidney function declined 83 percent higher in smokers compared to those who had never smoked.
The rate of kidney decline worsened with more smoking: those who smoked up to 19 cigarettes daily had 75 percent greater decline in kidney function and those who smoked 20 or more cigarettes a day had a 97 percent greater decline in kidney function.
Smokers had 38 percent higher inflammation levels compared to non-smokers.
“It’s important for those who have risk factors for kidney disease to realize that smoking is a significant risk factor and could ultimately end up leading to dialysis,” Hall said. “And once you have kidney disease, it exacerbates the risk of cardiovascular diseases.”
African-Americans are disproportionately affected by chronic kidney disease because of higher rates of hypertension, obesity and diabetes, and may be more susceptible to adverse effects of smoking to the kidneys. Yet little data exist examining the effects of smoking and kidney disease among African-Americans.
While blacks are less likely than whites to smoke, their metabolism of substances in cigarettes also differs compared with other ethnic groups.
Menthol-flavored cigarettes — popular among many African-American smokers — has been associated with increased concentrations of blood cadmium, a toxic metal used in protective coatings. Exposure to low levels of the metal has also been linked to kidney damage.
“We should be aggressive with screening patients who have risk factors for kidney disease by finding out if they smoke and, if so, encourage them to quit or cut back as much as possible if they can’t quit,” Hall said. “There does seem to be a dose-dependent effect, meaning patients who smoke more are at higher risk for having worsening kidney injury over time.”