Higher pregnancy rate in women who switched from conventional to nocturnal home hemodialysis


Mounting evidence suggests that nocturnal hemodialysis (NHD) has advantages over conventional hemodialysis (CHD), and improved pregnancy rates may be one of them, according to a small study by Canadian researchers.

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The study, led by Christopher Chan, MD, assistant professor of medicine at the University of Toronto, showed that women on NHD had a conception rate of 15.6%, which is substantially higher than the benchmark 2.2% rate found in a previous study by another research team.

The pregnancy analysis focused on five female patients who became pregnant while being treated with NHD through the University Health Network, St. Michael’s Hospital, and the Humber River Regional Hospital in Toronto between 2001 and 2006.


The five women, who were among 45 women of childbearing age who received NHD in Toronto in that period, had a total of seven pregnancies. Six of these resulted in live births and the seventh was terminated early because the woman’s obstetrician was concerned about it being a molar pregnancy.


At conception, the five women had an average age of 32 years. Their mean duration of NHD before pregnancy was three years, with all patients previously receiving CHD; one woman had also been on peritoneal dialysis. The women’s average number of prescribed NHD hours per week was 48.


Each woman’s BP remained within normal physiological ranges during gestation, although two of the women needed antihypertensive medication to achieve this. Furthermore, the rate of complications was lower in the six babies than that documented in the literature. Findings appear in the Clinical Journal of the American Society of Nephrology (2008;3:392-396).


“Many high-risk obstetricians provide at least a comment about therapeutic abortion in the record of a patient who has end-stage renal failure, because of the risk of failure of the pregnancy,” said Dr. Chan, medical director for home hemodialysis at the University Health Network.


“We now have achieved results that indicate there is a different approach to the problem; if someone with end-stage renal disease would like to have a family, and she is suitable for home hemodialysis, we would first train the person to do home nocturnal dialysis, get the uremia controlled as intensely as possible, and then advise her to try to have a family.”


In an accompanying editorial, Susan Hou, MD, professor of nephrology at Loyola University Medical Center in Maywood, Ill., observed that the new study “is the most encouraging report I have seen since the first time I started a pregnant woman on dialysis in 1984 and since the first successful pregnancy in a dialysis patient reported in 1971.” Despite the small number of patients and limitations of the study, she added, “it is hard to escape the conclusion that the better outcomes were the result of longer dialysis times.”


Dr. Hou concluded that it seems reasonable to offer NHD to pregnant women and to suggest it to women who want to become pregnant.

Another researcher who has studied NHD, John Burkart, MD, professor of nephrology at Wake Forest University School of Medicine in Winston-Salem, N.C., commented: “The significance of the fact that there seems to be a higher pregnancy rate while on NHD suggests that there are a lot of other biological benefits accruing.”


The new study adds to a growing body of evidence demonstrating that NHD is associated with improved health outcomes compared with CHD. At the recent National Kidney Foundation 2008 Spring Clinical Meetings in Grapevine, Tex., researchers reported that NHD was associated with improved nutrition compared with CHD as suggested by such measures as increases in body weight and protein and vegetable intake.


Dr. Chan’s group previously showed that switching patients from conventional to NHD increases vitamin D levels and improves cognition. More recently, the team demonstrated that NHD may reduce the risk of cardiovascular-related hospitalizations. The finding is based on a study of 32 people who received NHD in Toronto between 1999 and 2003. The team compared NHD patients’ outcomes to those of 42 people on CHD in the same period.


The hospitalization rate for dialysis- or cardiovascular-related admissions dropped from 0.5 per patient-year to 0.17 among those who switched to NHD, the researchers reported in Clinical Nephrology (2008;69:33-39). It was 0.48 per patient-year at baseline and 0.40 at the end of the study among those on CHD. In the NHD group, access problems were the most common cause of hospitalization, accounting for 56% of admissions. Cardiovascular problems accounted for 9% of hospitalizations in NHD patients versus 37% among patients on CHD.


“The hospitalization-rate results are not surprising as they are consistent with other observations that there is a reduction in the cardiovascular-related hospitalization rate with NHD,” Dr. Burkart noted. “It’s not a randomized, controlled trial, and it doesn’t prove you would live longer with NHD. But it’s another piece of information regarding why people should consider NHD as a treatment for their end-stage renal disease.”


At the European Renal Association-European Dialysis and Transplant Association congress in Barcelona last year, Bruce Culleton, MD, of the University of Calgary in Alberta, and colleagues reported study findings showing that NHD improves both cardiac and metabolic parameters and reduces the need for medication compared with CHD.


At six months, the mean left ventricular mass for patients on NHD was 13.8 grams less than baseline measurements compared with a mean increase of 1.5 grams for patients on CHD. Systolic BP declined by 7 mm Hg in the NHD group but increased by 4 mm Hg in the CHD group. Additionally, mean serum phosphate levels declined by 0.37 mmol/L in the NHD patients but increased by 0.11 mmol/L in the CHD patients.