Jim Kling

May 30, 2013

ISTANBUL, Turkey — A worldwide analysis of patients on dialysis reveals that more women than men die during treatment. Researchers suggest that catheter use and control of secondary hyperparathyroidism underlie the surprising mortality rate.

"Men and women have a lot of differences genetically, and there are many studies out there suggesting that treatments should be personalized according to sex," said Manfred Hecking, MD, a resident in nephrology and dialysis at the Medical University of Vienna in Austria. He also works with the Arbor Research Collaborative for Health in Ann Arbor, Michigan, which is a nonprofit organization that conducts studies of epidemiology and public health.

Dr. Hecking presented the study results here at the European Renal Association-European Dialysis and Transplant Association 50th Congress

The researchers analyzed male and female participants in the international Dialysis Outcomes and Practice Patterns Study (DOPPS) for characteristics and mortality risk.

 
Women have a natural survival advantage over men, but it is almost completely eradicated in dialysis patients. That is striking.
 

They used Cox regression models to evaluate mortality in the 36,216 patients. Because of regional variation in the differences between male and female participants, the researchers performed separate analyses for Japan and for North America, and combined analyses for Australia, Europe, New Zealand.

The researchers report that hypertension occurred less frequently in women than in men, diabetes occurred more frequently, and levels of serum phosphorous were similar.

There were significant regional mortality differences by sex. In principle, the mortality ratio of women to men should be 0.6, because that is the mortality ratio found in the general population, according to Dr. Hecking. However, in many countries, that ratio is closer to 1.0 in dialysis patients. "Women have a natural survival advantage over men, but it is almost completely eradicated in dialysis patients. That is striking," he said.

Table. Mean Characteristics of Male and Female Dialysis Patients

Characteristic Females Males P value
Composition 43% 57% <.001
Age 63.1 years 61.9 years <.001
Length of time on dialysis 5.4 years 5.2 years <.001
Body mass index 25.3 kg/m² 24.6 kg/m² <.001
Obesity 21.2% 13.4% <.001
Serum creatinine 8.4 mg/dL 10.0 mg/dL <.001
Parathyroid hormone 302 pg/mL 285 pg/mL <.001
Catheter use 18.5% 12.4% <.001

 

A key issue is the underlying cause of that difference. "It could be that dialysis is a deadly process that affects men and women equally. Or it could be that care for women is different than care for men, and we might actually get closer to the 0.6 figure by improving care for women on dialysis," Dr. Hecking explained.

The data suggest a possible culprit. The frequency of catheter access use is significantly different in men and women; after adjustment for that, survival in women improved. "This could be an indication that catheters are a modifiable practice and women could be treated better," he noted.

The difference in parathyroid hormone suggests that control of secondary hyperparathyroidism is another factor.

"It's an interesting study," said Christoph Wanner, MD, from the University Clinic Würzburg in Germany. "This is the only dataset in which you can do this type of analysis, covering many parts of the world and different ethnicities. It's a huge database with a long time span," he noted.

"Because these survival differences are seen not in only 1 country, it would be interesting to compare" differences in dialysis treatment between men and women in different countries, Dr. Wanner told Medscape Medical News.

Dr. Hecking and Dr. Wanner have disclosed no relevant financial relationships.

European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) 50th Congress: Abstract MP563. Presented May 20, 2013.

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