How Big Is Too Big?: Donor Severe Obesity and Heart Transplant Outcomes

As the population becomes increasingly obese, so does the pool of potential organ donors. We sought to investigate the impact of donors with body mass index ≥40 (severe obesity) on heart transplant outcomes.

Single-organ first-time adult heart transplants from 2003 to 2017 were evaluated from the United Network for Organ Sharing database and stratified by donor severe obesity status (body mass index ≥40). Demographics were compared, and univariate and risk-adjusted analyses evaluated the relationship between severe obesity and short-term outcomes and long-term mortality. Further analysis evaluated the prevalence of severe obesity within the pool of organ donation candidates.

A total of 26 532 transplants were evaluated, of which 939 (3.5%) had donors with body mass index ≥40, with prevalence increasing over time (2.2% in 2003, 5.3% in 2017). Severely obese donors more likely had diabetes mellitus (10.4% versus 3.1%, P<0.01) and hypertension (33.3% versus 14.8%, P<0.01), and 67.4% were size mismatched (donor weight >130% of recipient). Short-term outcomes were similar, including 1-year survival (10.6% versus 10.7%), with no significant difference in unadjusted and risk-adjusted long-term survival (log-rank P=0.67, hazard ratio, 0.928, P=0.30). Organ donation candidates also exhibited an increase in severe obesity over time, from 3.5% to 6.8%, with a lower proportion of hearts from severely obese donors being transplanted (19.5% versus 31.6%, P<0.01).

Donor severe obesity was not associated with adverse post-transplant outcomes. Increased evaluation of hearts from obese donors, even those with body mass index ≥40, has the potential to expand the critically low donor pool.