Association of a new waitlist mortality metric with likelihood of delisting among kidney transplant candidates.

Prior transplant regulations have resulted in unintended consequences, including decreased volumes. A new waitlist mortality metric for centers was approved on December 6, 2021. We hypothesized that kidney candidates waiting for transplant after this approval would be at increased risk of delisting. Adult kidney candidates waiting between January 1, 2022, and December 2, 2024 (era 2) were subject to the new metric and compared to candidates waiting between June 1, 2020, and December 31, 2021 (era 1). We estimated the time to removal from the waitlist for being too sick for transplant or "other" causes, accounting for the competing risk of death and transplant, before and after metric approval. We assessed for effect modification by demographics. The cause-specific hazard of delisting for being too sick increased by 25% among candidates in era 2 compared to era 1 (95% confidence interval [CI]: 1.20, 1.30); the cause-specific hazard of delisting for "other" causes increased by 34% (95% CI: 1.28, 1.40). These increases were accompanied by a decrease in waitlist mortality (cause-specific hazard ratio: 0.80, 95% CI: 0.78, 0.83) and an increase in transplant (cause-specific hazard ratio: 1.09, 95% CI: 1.08, 1.11) among those remaining on the list. Delisting disproportionately increased among Black candidates and candidates with insurance other than private, Medicare, or Medicaid. Implementation of outcome metrics without a corresponding focus on access may result in unintended consequences.