Geographic Disparities in Lung Transplant Rates

Martin Kosztowski; Sheng Zhou; Errol Bush; Robert S. Higgins; Dorry L. Segev; Sommer E. Gentry

Disclosures

American Journal of Transplantation. 2019;19(5):1491-1497. 

In This Article

Abstract and Introduction

Abstract

In November 2017, in response to a lawsuit from a New York City lung transplant candidate, an emergency change to the lung allocation policy eliminated the donation service area (DSA) as the first geographic tier of allocation. The lawsuit claimed that DSA borders are arbitrary and that allocation should be based on medical priority. We investigated whether deceased-donor lung transplant (LT) rates differed substantially between DSAs in the United States before the policy change. We estimated LT rates per active person-year using multilevel Poisson regression and empirical Bayes methods. We found that the median incidence rate ratio (MIRR) of transplant rates between DSAs was 2.05, meaning a candidate could be expected to double their LT rate by changing their DSA. This can be compared directly to a 1.54-fold increase in LT rate that we found associated with an increase in lung allocation score (LAS) category from 38–42 to 42–50. Changing a candidate's DSA would have had a greater impact on the candidate's LT rate than changing LAS categories from 38–42 to 42–50. In summary, we found that the DSA of listing was a major determinant of LT rate for candidates across the country before the emergency lung allocation change.

Introduction

The 1998 Final Rule sought to "assure that allocation of scarce organs will be based on common medical criteria, not accidents of geography."[1] In accordance with the Final Rule's emphasis on ranking candidates by medical urgency, the lung allocation score (LAS) was introduced in 2005. The LAS is a weighted combination of the predicted risk of death on the waiting list and the predicted likelihood of survival during the first year after transplantation.[2,3] Although there is broad consensus that the LAS system was a vast improvement over waiting list time, the 2005 policy change did not address the impact of geography on allocation. Transplant candidates are prioritized by LAS, but lungs were offered first to candidates within the boundaries of the donor's donation service area (DSA).

On November 19, 2017, Miriam Holman filed a lawsuit against the U.S. Department of Health and Human Services challenging the DSA as the first unit of allocation.[4] She was a 21-year-old woman with pulmonary hypertension who was hospitalized in an intensive care unit (ICU) in New York City with an LAS of greater than 90. The lawsuit claimed that "by prioritizing available lungs to candidates in the local DSA, The Organ Procurement and Transplantation Network (OPTN) policy limits the number of lungs available to high priority transplant candidates like Miriam and effectively allocates available lungs based on a candidate's place of residence instead of medical priority." The United Network for Organ Sharing (UNOS) Executive Committee acknowledged that lung allocation within a DSA was inconsistent with the Final Rule, and 5 days after the lawsuit was filed, it agreed to eliminate the DSA as the first unit of allocation and instead use a 250 nautical mile circle from the donor hospital.[5]

At the time of the lawsuit, were candidates in New York City uniquely disadvantaged in access to deceased-donor lungs, or were candidates in transplant centers across the country experiencing disparate access to transplantation? The present study seeks to quantify geographic disparity in lung transplant (LT) rate prior to the allocation policy change. We used a metric called the median incidence rate ratio (MIRR) that has also been used to measure geographic disparity in kidney and liver transplantation (M.G. Bowring, E.H. Chow, X. Luo, et al., unpublished data, 2018).[6] MIRR is a robust metric of heterogeneity in LT rates across DSAs that accounts for time-varying allocation LAS and characterizes the variation in transplant rates per waitlist-year across DSAs. MIRR has a natural interpretation as the increase in access to LT that candidates could expect if they moved from their DSA to a DSA with higher transplant rates.

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