Cytomegalovirus-related disease and risk of acute rejection in renal transplant recipients: a cohort study with case-control analyses

The relationship between a cytomegalovirus (CMV) infection and the acute re jection of a renal transplant is not well established. The aim of the study was to document whether the clinical presentation of a CMV infection as a diffuse inflammatory disease or as a clinically asymtomatic illness is a ri sk factor of acute renal transplant rejection. One hundred and ninety-two c onsecutive renal transplant recipients were included in a historical cohort study for exposed - non exposed analyses. CMV infection after transplantat ion was the exposure factor. Before transplantation, 113 patients had antib odies against CMV and 79 were seronegative. The patients were divided into three groups: Group 1 consisted of 64 patients who had neither clinical sig ns of CMV disease nor CMV serological changes after transplantation, Group 2 consisted of 77 seropositive patients with asymptomatic viremia, and Grou p 3 consisted of 51 seropositive patients with clinical signs of diffuse in flammation that included fever, neutropenia, and various visceral involveme nts (CMV disease). Groups 2 and 3, the seropositive patients, were paired w ith Group 1 patients. Acute rejection was considered as CMV-induced when it occurred within one month following viremia, during the first year after t ransplantation. Transplant patients with CMV disease, had a significant lik elihood of developing acute rejection after CMV infection or reactivation ( P < 0.01). The odds ratio for developing rejection was 5.98, 95 % confidenc e interval: 1.21-29.40. Such a link was not documented for recipients with asymptomatic CMV infection. In conclusion CMV disease, but not asymptomatic viremia, is a risk factor of acute renal transplant rejection. On epidemio logical grounds, these results support the hypothesis that factors controll ing both the viral replication and the diffuse inflammatory process are imp licated in acute graft rejection.