Study suggests time of day may affect dialysis

CHICAGO -- Some kidney failure patients live longer if they undergo dialysis in the morning instead of the afternoon, a study suggests. But some kidney specialists say the study was seriously flawed.

The Emory University study involved 242 end-stage kidney failure patients 60 and older. A total of 167 had dialysis in the morning and 75 had the procedure in the afternoon. The patients were followed for several years.

The morning patients survived more than a year longer than the afternoon group. Their average survival was two years and seven months, compared with one year and three months for the afternoon group.

Researcher Donald Bliwise and his co-authors said the reason is unclear, but they speculated that the morning patients may have dozed during their treatments and were better-rested than the afternoon ones.

The study, published in Wednesday's Journal of the American Medical Association, is not the first study to suggest a connection between health problems and the time of day.

Previous research has shown that heart attacks are more common in the morning and that night-shift workers have more health problems. But experts not involved in the study said it does not prove that time of day makes any difference for dialysis.

For one thing, there were more blacks in the morning group than in the afternoon one, and blacks on dialysis are known to have better survival rates than whites, said Dr. Paul Scheel, a Johns Hopkins University nephrologist.

The morning patients weighed more overall than the afternoon ones. Heavier patients tend to do better on dialysis because their treatments are longer, said Dr. Leslie Spry.