Incidence of conversion to active waitlist status among temporarily inactive obese renal transplant candidates.

Background: Candidates may be active or temporarily inactive (status 7) on the kidney transplant waiting list. One reason candidates may be inactive is for a "weight currently inappropriate for transplantation." We hypothesized that many of these candidates would not achieve active status.

Methods: Using OPTN/UNOS data from 2006 to 2012, we used competing risks methods to determine the cumulative incidence of conversion to active status (activation), death, and delisting before conversion among 1679 obese adult kidney candidates designated as status 7 because of a weight inappropriate for transplantation. Fine and Gray competing risks regression was performed to characterize factors associated with conversion to active status in the overall study population and of transplantation among a subgroup of activated candidates.

Results: At 6 years, the cumulative incidence of activation was 49%, of death before conversion was 15%, and of delisting was 21%. Higher body mass index (BMI) was strongly associated with a decreased subhazard of activation (BMI ≥45 versus 30-34.9, sHR: 0.22; 95% CI, 0.16-0.33). Female sex, diabetic end-stage renal disease, history of a previous transplant, panel reactive antibodies less than 80%, dialysis dependence at listing, and UNOS region 5 were negatively associated with activation. Among activated candidates, the cumulative incidence of transplantation at 6 years after initial waitlisting was 61%.

Conclusion: Our findings indicate that half of obese status 7 candidates with a weight inappropriate for transplantation will not achieve active waitlist status. BMI at listing had a strong association with conversion to active status; comorbid factors and regional variation also impact activation.