Impact of Social Deprivation on Mortality 1- and 5-Years Post Kidney Transplantation in England Over the Last Decade

Abstract

Introduction: Social deprivation is an important determinant of poor health outcomes, with greater degrees of deprivation associated with increased mortality. In the context of kidney transplantation, studies have demonstrated an adverse association between social deprivation and post-transplant outcome. However several limitations prohibit clear interpretation of these earlier studies and confines extrapolation between different countries. The aim of this study was to assess the impact of social deprivation on mortality post kidney transplantation in England in the context of universal health coverage. Methods: Data was obtained from Hospital Episode Statistics (HES), an administrative data warehouse containing admissions to all National Health Service hospitals in England. Data extraction was facilitated utilizing codes on procedural classification (Office of Population Censuses and Surveys Classification of Interventions and Procedures [OPCS-4]) and medical classification (ICD-10). We obtained data on all kidney transplant procedures performed in England between April 2001 and March 2010 with patient demographics obtained at time of transplant including age, sex, ethnicity, medical co-morbidities and social deprivation. The latter assessment was based upon the Index of Multiple Deprivation (IMD 2007) and comprised an aggregate of the following seven parameters; income, employment, health deprivation and disability, education skills and training, barriers to housing and services, crime and living environment. On the IMD 2007 quintile scale, 1 represented the most deprived and 5 the least deprived classification respectively. The primary outcome measure was mortality 1-year post kidney transplantation (HES data linked to Office for National Statistics to identify all mortality events), with 5-year mortality (for recipients between 2001-2006) the secondary outcome measure. Logistic regression algorithms were performed (R stats package) to identify independent factors associated with mortality (p < 0.05 considered significant). Results: Data analysis was performed on 15,218 kidney transplant procedures performed in England between 2001-2010 (adult and paediatric). Breakdown of patients by IMD 2007 classification were (from most to least deprived respectively): 1 (22%, n=3238), 2 (21%, n=3201), 3 (20%, n=2986), 4 (18%, n=2694) and 5 (18%, n=2675), with 198 (1%) unknown. Modal score age category for kidney transplant recipients per IMD 2007 quintile were: 1 (age 40), 2 (age 41), 3 (age 47), 4 (age 54) and 5 (45). There were 473 recorded deaths at 1-year post kidney transplantation for this study population. 1-year patient survival post kidney transplantation per IMD 2007 quintile was: 1 (96.3%), 2 (97.0%), 3 (96.8%), 4 (97.1%) and 5 (97.5%). Logistic regression analysis identified social deprivation quintile as an independent predictor for both 1-and 5-year patient mortality (factored against age, sex, ethnicity and medical co-morbidities such as diabetes, cardiovascular or lung disease). Compared to most deprived individuals, the least deprived recipients had decreased risk of mortality at 1-year post kidney transplant (OR 0.89, p = 0.001) and 5-years post kidney transplant (OR 0.90, p < 0.001). Conclusion: Socioeconomic deprivation is independently associated with increased mortality 1- and 5-years post kidney transplantation. This link was independent of age, sex, ethnicity and medical co-morbidities within the context of a universal health coverage system in England.