Impact of comorbidity on outcome in kidney transplant recipients: a retrospective study in Italy

The aim of this study was to relate in-hospital mortality (IHM), cardiovascular events (CVEs) and non-immunologic comorbidity evaluated on the basis of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codification, in Italian kidney transplant recipients (KTRs). We evaluated IHM and admissions due to CVEs between 2000 and 2013 recorded in the database of the region Emilia Romagna. The Elixhauser score was calculated for evaluation of non-immunologic comorbidity. Three main outcomes (i.e. IHM, admission due to major CVEs and combined outcome) were the dependent variables of the multivariate models, while age, gender and Elixhauser score were the independent ones. During the examined period, a total of 9063 admissions in 3648 KTRs were recorded; 1945 patients were males (53.3 %) and 1703 females (46.7 %) and the mean age was 52.9 ± 13.1 years. The non-immunological impaired status of the KTRs, examined by the Elixhauser score, was 3.88 ± 4.29. During the 14-year follow-up period, IHM for any cause was 3.2 % (n = 117), and admissions due to CVEs were 527 (5.8 %). Age and comorbidity were independently associated with CVEs, IHM and the combined outcome. Male gender was independently associated with IHM and combined outcome, but not with CVEs. Evaluation of non-immunological comorbidity is important in KTRs and identification of high-risk patients for major clinical events could improve outcome. Moreover, comorbidity could be even more important in chronic kidney disease patients who are waiting for a kidney transplant.