'Weekend Effect' May Limit Use of Deceased Donor Kidneys

Diana Phillips

July 18, 2016

The likelihood of a deceased donor kidney being procured and transplanted may depend on the day of the week it becomes available, according to a study published in the July issue of Kidney International.

Sumit Mohan, MD, MPH, from the Division of Nephrology, Columbia University Medical Center, New York City, and colleagues report that as many as one in five deceased donor kidneys may be discarded because of the so-called "weekend effect," leading experts to call for a reevaluation of resource allocation in transplant centers and the factors that contribute to utilization decisions.

The "weekend effect" describes the association between worse outcomes among patients who receive hospital care during the weekend vs weekdays. Although the phenomenon is well reported in the literature, recent studies suggest the underlying mechanisms are more complex.

For the current study, the researchers examined information from the Scientific Registry of Transplant Recipients to investigate the possible influence of weekend resource limitation on kidney transplantation. Of 181,799 deceased donor kidneys recovered for transplantation in the United States from 2000 to 2013, 144,943 were available for procurement from Sunday through Thursday, and 57,013 were available Friday or Saturday.

Of the organs procured for transplant, 18.6% of the weekend kidneys were discarded compared with 16.4% of the weekday kidneys, the authors report, indicating that the weekend kidneys were significantly more likely to be discarded (odds ratio, 1.16; 95% confidence interval, 1.13 - 1.19; P < .001). The increased risk persisted even after adjusting for organ quality based on Kidney Donor Profile Index (KDPI) scores (adjusted odds ratio, 1.13; 95% confidence interval, 1.10 - 1.17), they report.

"The odds of discard of a kidney after procurement tended to increase over the week," as did the quality of discards, the authors state.

The researchers also looked at kidney discard rates by donor service area and transplant center and observed considerable variation both geographically and by center size in the proportion of weekend transplants. Specifically, a greater than expected share of weekend transplants occurred in Arkansas, Alabama, South Carolina, Kentucky, West Virginia, and Virginia, as well as Minnesota, Iowa, and Ohio. A smaller than expected share of weekend transplants occurred in Wyoming, Utah, Colorado and Nevada, as well as Arizona and Oklahoma (28.58% - 33.51% vs 18.98% - 25.55%). Larger transplant centers were more likely to use kidneys available for transplant during the weekend than were smaller centers (P = .037).

The findings also indicate that weekend kidneys were significantly more likely to be shared without payback (P = .001) and experienced shorter cold ischemia times (P = .002), the authors report. The latter finding may suggest an awareness among transplant experts of the increased challenge of accepting organs during the weekend "and the development of organ offer strategies to mitigate this effect," they hypothesize. "Alternatively, transplant centers may use lower thresholds for cold ischemia time for accepting a deceased donor kidney over the weekend."

The temporal kidney procurement trends and use patterns independent of kidney quality, together with the increased use of weekend kidneys at large transplant centers, "suggests that organizational and systemic factors that extend beyond the quality of the available organ appear to be contributing to the high rate of discard of kidneys from deceased donors in the United States," the authors write. For example, limited surgical manpower on weekends may contribute to a reluctance or inability, particularly among smaller transplant centers, to accept organs for transplant, they state. "Large transplant centers tend to have more resources, including manpower, and while they may also experience resource constraints over the weekend, the impact may be smaller."

Investigating the short- and long-term outcomes of transplantation that takes space at centers with high weekend use "could potentially provide an opportunity for quality improvement efforts, as well as changes in policy to improve organ utilization," the authors conclude.

Although limited by the lack of comprehensive data regarding the specific reasons for kidney discard, which the KDPI does not capture, the study findings point to "an important issue that warrants attention by the transplant community," according to Sunita K. S. Singh, Division of Nephrology and the Kidney Transplant Program, Toronto General Hospital, University Health Network, and Institute of Health Policy, Management and Evaluation, University of Toronto, Ontario, Canada, and S. Joseph Kim, MD, PhD, MHS, Division of Nephrology and the Kidney Transplant Program, Toronto General Hospital, University Health Network, and Institute of Health Policy, Management and Evaluation, University of Toronto, Ontario, Canada, and Division of Nephrology and the Renal Transplant Program, St. Michael's Hospital, Toronto, Ontario, Canada.

If the weekday kidney discard rate of 16.4% in the study were applied to the reported number of kidneys recovered over the weekends, "an additional 1123 deceased donor kidneys would have been available for transplantation if the weekend effect was eliminated," they write in an accompanying commentary. "Assuming that the quality of kidneys available for transplantation were similar on weekends versus weekdays, these findings have important implications for patients on the transplant waiting list, because an additional 80 patients per year could have been transplanted."

Improved data collection to determine the appropriateness of discard decisions and additional research into the healthcare delivery variables that drive discard decisions may yield useful insights into necessary organizational procedures and resource allocation changes to achieve parity between weekend and weekday procurement and use of deceased donor kidneys, the commentators write.

"Given that kidney transplantation improves life expectancy and is less costly to the health care system than chronic dialysis, a careful reevaluation of resource allocation on weekdays versus weekends in transplant centers is need to ensure that the benefits of transplantation is maximized for the patients who need this life-saving therapy," they stress.

The authors and commentators have disclosed no relevant financial conflicts.

Kidney Int. 2016;90:26-28, 157-163. Article abstract, Commentary extract

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