Cytomegalovirus (CMV) excretion as a factor in the severity of CMV disease in kidney and simultaneous kidney and pancreas transplantation

Abstract

The aim of the study was to evaluate the virological parameters associated with the severity of cytomegalovirus (CMV) disease in renal and simultaneous renal and pancreatic transplantation. The association of the viral profile and the severity of the viral disease was analysed taking into account different confounding variables susceptible to linkage with the severity of the CMV infection and the viral parameters. All the patients transplanted between 1 January 1989 and 31 December 1990, a total of 242, were prospectively followed by viral cultures in blood and urine and by serological methods using the detection of CMV-specific IgM and the complement fixation (CF) test. The samples were taken systematically each week for the first month and then at day 90, 180 and every 6 months and also in cases of clinical manifestations related to viral disease. CMV infection was diagnosed virologically by the presence of viraemia, viruria, IgM, or a significant rise in CMV antibody titre in CF. CMV disease was classified as asymptomatic, mild (fever and/or leukopenia), moderate (fever, leukopenia and liver abnormalities), severe (CMV pneumopathy and/or gastrointestinal disease) or fatal. The incidence of CMV infection was 65% (157/242): 32% asymptomatic, 36% mild, 30% moderate and 2% severe. The presence of IgM was associated with the severity of CMV disease: 51.4% of moderate and severe CMV infections in the group with IgM versus only 16% in the group without IgM (P < 0.0001). The risk of having severe or moderate CMV disease was 3.28 times higher in patients with positive IgM. However the serological changes in CF were not significantly associated with the severity of the viral disease since 34.6 % of the patients with CF changes had a severe form versus 20.8% in the group without CF modification. Viruria was significantly associated with moderate or severe infection: 43.6% of the patients with viruria had severe infection versus only 12.5% in the patients without viruria (P < 0.0002). The risk of having moderate or severe CMV disease was 3.48 times higher in the patients with viruria. Viraemia was also associated with more severe CMV infection: 48.6% of moderate or severe CMV infection in the group of patients with viraemia versus 19% in the group without viraemia (P < 0.0001). The risk of having severe or moderate CMV infection was 2.58 times higher in the patients with viraemia. Viraemia was not more associated with severe CMV infection than viruria. Using the maximum likelihood ratio method and the logistic regression model, CMV-specific IgM, viruria and viraemia were each shown to be associated with the severity of CMV disease and the addition of one parameter to the other(s), whatever the type (except the CF changes) and whatever the order of this addition, did not remove the link between the severity and IgM, viruria and viremia. The incidence of severe and moderate CMV disease increased with the number of positive viral parameters (PVP) from 2% of moderate and severe infections in the group with one PVP, to 28% in the group with two PVP, to 39% in the group with three PVP and 68% in the group with four PVP (trend, 35.95; P < 0.0001). Taking the absolute risk of the group of patients without IgM, viruria or viraemia as the basal level, the observed relative risk of severe CMV infection varied from 6.45 in the group with positive IgM without viruria or viraemia, to 10.74 in the group with positive IgM and viruria without viraemia and to 22.5 in the group with the three positive parameters IgM, viruria and viraemia. The different potential confounding factors (recipient and donor serology, renal or renal and pancreatic transplantation, DR compatibility, rejection before CMV infection) did not modify the link between the viral profile and the severity of CMV disease. This study suggests that the severity of CMV disease might be linked to the overspread of the virus as well as to the consequences of a CMV-specific humoral immune response.