Are we correctly assessing transplant outcomes by using deprivation indices?

Abstract

To the Editor, We read the article “The influence of socioeconomic deprivation on outcomes in pancreas transplantation in England: registry data analysis” by Asderakis et al from the Cardiff Group with great interest.1Asderakis A Khalid U Madden S Dayan C The influence of socioeconomic deprivation on outcomes in pancreas transplantation in England: registry data analysis.Am J Transplant. 2018; 18: 1380-1387Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar They have pertinently proved that socioeconomic deprivation is a factor for pancreas graft and patient survival. The same group had earlier reported similar outcomes for renal transplantation in their study in 2010.2Stephens MR Evans M Ilham MA Marsden A Asderakis A The influence of socioeconomic deprivation on outcomes following renal transplantation in the United Kingdom.Am J Transplant. 2010; 10: 1605-1612Crossref PubMed Scopus (40) Google Scholar Multiple studies from the United Kingdom also have reported the related impact of socioeconomic deprivation and access to transplantation, kidney allograft outcomes, and mortality after commencing renal replacement therapy.3Begaj I Khosla S Ray D Sharif A Socioeconomic deprivation is independently associated with mortality post kidney transplantation.Kidney Int. 2013; 84: 803-809Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar Parallel outcomes have been reported from transplant of other organs and different patient groups in varied health models.4Thammana RV Knechtle SJ Romero R Heffron TG Daniels CT Patzer RE Racial and socioeconomic disparities in pediatric and young adult liver transplant outcomes.LiverTranspl. 2014; 20: 100-115Google Scholar,5Evans JD Kaptoge S Caleyachetty R et al.Socioeconomic deprivation and survival after heart transplantation in England.Circ Cardiovasc Qual Outcomes. 2016; 9: 695-703Crossref PubMed Scopus (24) Google Scholar The present study reports pancreas transplants done between 2004 and 2014, whereby during this period the English Index of Multiple Deprivation (EIMD) has had 3 modified versions: 2007, 2010, and 2015. From 2010 to 2017, a 17% change has been reported in deprivation index of English neighborhoods6Department for Communities and Local Government. English indices of deprivation 2015. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/465791/English_Indices_of_Deprivation_2015_Statistical_Release.pdf. Accessed August 5, 2018.Google Scholar. Between 2005 and 2016, net migration arising from internal migration (England) was 70.5/1000 population for predominantly rural areas and −105.1/of 1000 population for predominantly urban areas7Rural population and migration. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/682975/Rural_population_and_migration_February_2018.pdf. Accessed August 5, 2018.Google Scholar. With lack of electronic connectivity among 6 Pancreas Transplant Centers in England, it would be difficult to track patient outcomes if a transplant recipient migrates to another neighborhood that may be more or less deprived. It would be interesting to know how the change in relative deprivation over different versions of EIMD and reporting the transplant outcomes in view of significant population mobility was incorporated into the present registry-based study. The studies assessing influence of socioeconomic deprivation have used a static deprivation index that is effectively time variable. The lack of a single consistent time point for all indicators for Indices of Deprivations mars the effective relay of outcome studies. We thus feel that the present study along with others utilizing Indices for deprivation have an immortal time bias whereby time-fixed methodology has been utilized for a time-variable variant (eg, EIMD versions 2007, 2010, and 2015) to understand relationships between risk factors and clinical outcomes. The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.