Long-term mortality risk following live donor liver donation was nearly identical to that of matched live kidney donors as well as healthy, demographically matched controls, according to a report by Dr. Abimereki D. Muzaale and colleagues published in the February issue of Gastroenterology.

"Donor-related complications not resulting in immediate death or acute liver failure do not seem to result in decreased long-term longevity," they wrote.

Dr. Muzaale, of Johns Hopkins University, Baltimore, followed the 4,111 patients in the United States who had donated a portion of their livers between April 1, 1994, and March 31, 2011. The donors were followed for a median of 7.6 years (Gastroenterology 2012 February [doi:10.1053/j.gastro.2011.11.015]).

Most livers (77%) were donated to a biological relative of the donor. Nonspousal, nonbiologically related donations made up 17% of the total, and spousal donations made up the remaining 6%.

"All living donors had reportedly excellent hepatic and renal function" at the time of transplant, the researchers wrote. Body mass index was greater than 30 in 15% of the donors. At some point, 22% had smoked cigarettes, and 90% of the donors were under 50 years old.

This cohort was compared with live kidney donors, who were matched to the liver donors according to year of donation, age, gender, race, education background, and BMI. Finally, liver donors also were compared with a third cohort of healthy adults, similarly matched, from the National Health and Nutrition Examination Survey III (NHANES III). None of the NHANES III patients had comorbidities that might have deemed them ineligible for liver donation, according to the authors.

All deaths were determined from the Social Security Death Master File.

Overall, the researchers found that in the first 90 days after donation, 7 living liver donors died, for a rate of 1.7 deaths per 1,000 donors (95% confidence interval, 0.7-3.5). Compared with kidney donors, this rate was higher, but not significantly higher (0.5 deaths per 1,000 donors; 95% CI, 0.1-1.8, P = .09).

"By contrast, as would be anticipated, living liver donors had a significantly higher risk of early death than matched NHANES III participants who likely did not undergo a surgical procedure in their first 90 days of follow-up (P = .008)," wrote the authors.

Among the decedents, neither donor age, recipient age, portion of liver donated, center volume at time of donor death, nor cause of death correlated with 90-day mortality.

Causes of death included anaphylaxis, multiorgan failure, infection, drug overdose and suicide, and cardiovascular and respiratory arrest.

Beyond 90 days, however, the differences in mortality decreased even more among cohorts.

For example, at 2 years, live liver donors had a cumulative mortality of 0.3%, compared with 0.2% among kidney donors and 0.3% among healthy NHANES III participants.

At 5 years, the results were similar, with all three cohorts registering a 0.4% cumulative mortality.

By 9 years, liver donors could expect a 0.9% mortality rate, compared with 1.0% among the kidney donors and 0.8% among healthy controls.

Finally, at 11 years out, the respective mortality rates were once again similar or identical among cohorts, with 1.2% for liver donors, 1.2% for kidney donors, and 1.4% for healthy controls.

The authors conceded that the study was limited by the fact that live liver donors were "meticulously screened and likely more healthy than NHANES-III participants.

"The ideal comparison group would have included healthy individuals who were cleared for donation but did not proceed to donation," they wrote. "However, this comparison group was not available."

Dr. Muzaale and the authors of this study stated that they had no financial disclosures. They added that the Organ Procurement and Transplantation Network is supported by the U.S. Health Resources and Services Administration.