NEW YORK (Reuters Health) – Patients undergoing hemodialysis with a dialyzer that’s sterilized by electron beam have an increased risk of thrombocytopenia, a Canadian study has shown.“Because we were able to collect and analyze data from 2 large and distinct hemodialysis populations, we uncovered an association that might otherwise be missed or be reported only on a case-by-case basis,” Dr. Mercedeh Kiaii, at the University of British Columbia in Vancouver, and colleagues comment in their report in the October 19 issue of the Journal of the American Medical Association.The authors explain that the electron beam (e-beam) method has become popular for membrane sterilization. However, after the introduction of such dialyzers in one dialysis unit, significant thrombocytopenia was noted in 20 patients. This observation prompted a study of two hemodialysis populations using dialyzers from different manufacturers: 1706 patients in British Columbia and 425 in Alberta.Significant postdialysis thrombocytopenia was defined as the combination of both a platelet count of less than 11359,000/microliter and a count decrease of more than 15% from predialysis values.The team found that 7.2% of the patients in the British Columbia group and 7.3% of those in the Alberta cohort met both these criteria. On multivariate analysis, the adjusted odds ratio for thrombocytopenia associated with e-beam-sterilized dialyzer use was 2.52 (p=0.02).Not all patients were affected, the researchers point out, but they were unable to identify any patient characteristics, other than age, that were associated with postdialysis thrombocytopenia. “Thus, we suspect as yet unidentified patient-specific factors may contribute to the phenomenon,” they write.After the dialyzers were changed to non-e-beam sterilized machines in both provinces, the prevalence of significant postdialysis thrombocytopenia fell to just 2.1% in the British Columbia group and 1.6% among the Alberta patients, the report indicates.“These results support the hypothesis that the thrombocytopenia observed in this dialysis cohort is due to an idiosyncratic reaction to e-beam sterilized dialyzers,” Dr. Kiaii and colleagues conclude.They also note that this association is not just a Canadian phenomenon, as there have been three case reports with similar findings in two different US cities.In an accompanying editorial, Dr. Jonathan Himmelfarb, at the University of Washington, Seattle, comments: “Kiaii et al acknowledge that the mechanism by which e-beam sterilization contributes to thrombocytopenia risk is unknown and the clinical implications are also unclear at this time. Thus, many important questions remain to be investigated.”Source: http://www.jama.comJAMA 2011;306:1679-1687, 1707-1708.
