Impact of Cigarette Smoking among Living Donors on Kidney Transplant Graft Survival.

BACKGROUND: Current evidence on the impact of living donor smoking on kidney transplant outcomes is conflicting. This study aimed to evaluate the association between living donor smoking history and graft survival. We hypothesized that any donor smoking history is associated with increased risk of graft loss, but this risk is attenuated with donor smoking cessation, lower pack-year history and longer duration of smoking abstinence. METHODS: We conducted a retrospective cohort study using the Organ Procurement and Transplantation Network database, including 88,490 individuals who underwent living donor kidney-only transplantation between June 2004 and June 2022. The exposure was living donor smoking history (ever vs never, former vs active, pack-year history, years of abstinence)The primary outcome was all-cause graft loss, analyzed using multivariable Cox proportional hazard models. Secondary outcomes of delayed graft function and first year acute rejection were analyzed using multivariable logistic regression. RESULTS: Recipients of organs from donors with any smoking history had an increased risk of all-cause graft loss (HR: 1.13 [1.09-1.16], p<0.001) and first year acute rejection (OR: 1.18 [1.11-1.25], p<0.001). Compared to never smokers, both active and prior smoking in the donor was associated with a higher hazard of graft loss (HR:1.19 [1.13-1.25] and 1.10 [1.07-1.14], respectively, both p<0.001), with higher hazard in active vs. prior (p=0.02). Grafts from donors with >20 pack-year smoking history experienced the highest risk of graft loss (HR: 1.29 [1.21-1.37], p<00.1), delayed graft function (OR: 1.24 [1.03-1.49], p=0.001), and acute rejection (OR: 1.31 [1.16-1.50], p<0.001). CONCLUSIONS: Cigarette smoking in living kidney donors is associated with modest increase in a risk for all-cause graft loss, with the greatest risk observed among recipients of grafts from donors with a significant pack-year smoking history.