from Market Design at https://bit.ly/31HV5uy on August 31, 2020 at 12:53PM
Two papers have made me think about the power of econometric methods applied to studies of medical issues related to matching deceased donor kidneys to patients.
I recently heard Chuck Manski give a seminar on this paper published last year in PNAS:
One thing I took away from it is that proportional hazard (Cox) models are very popular in the medical literature, but they assume that effects (e.g. rejection of a graft) are proportional to time, and there are immunological processes that don’t in fact have a constant hazard rate, but build up over time, so that isn’t a good model for those things.
Charles F. Manski, Anat R. Tambur, and Michael Gmeiner, PNAS October 8, 2019 116 (41) 20339-20345
"Abstract: We consider prediction of graft survival when a kidney from a deceased donor is transplanted into a recipient, with a focus on the variation of survival with degree of human leukocyte antigen (HLA) mismatch. Previous studies have used data from the Scientific Registry of Transplant Recipients (SRTR) to predict survival conditional on partial characterization of HLA mismatch. Whereas earlier studies assumed proportional hazards models, we used nonparametric regression methods. These do not make the unrealistic assumption that relative risks are invariant as a function of time since transplant, and hence should be more accurate. To refine the predictions possible with partial knowledge of HLA mismatch, it has been suggested that HaploStats statistics on the frequencies of haplotypes within specified ethnic/national populations be used to impute complete HLA types. We counsel against this, showing that it cannot improve predictions on average and sometimes yields suboptimal transplant decisions. We show that the HaploStats frequency statistics are nevertheless useful when combined appropriately with the SRTR data. Analysis of the ecological inference problem shows that informative bounds on graft survival probabilities conditional on refined HLA typing are achievable by combining SRTR and HaploStats data with immunological knowledge of the relative effects of mismatch at different HLA loci."
And here’s a recent working paper that says that if we want to maximize life years added by transplant, more organs should go more quickly to healthier patients:
Nikhil Agarwal, Charles Hodgson, Paulo Somaini, August 17, 2020