Effect of treatment with cyclosporine versus azathioprine on incidence and severity of cytomegalovirus infection posttransplantation.

The incidence and severity of cytomegalovirus (CMV) infection were evaluated in 24 renal transplant patients treated with steroids and cyclosporine and compared with 40 patients treated with steroids and azathioprine: 58% of patients receiving azathioprine and 33% of patients receiving cyclosporine required additional therapy with antithymocyte globulin (ATG) to treat steroid-resistant rejections. CMV antibody titers and cultures of urine and saliva were determined monthly for 4-6 months following transplant in all patients. Both the frequency of CMV infection (occurring in 58% of patients on steroids and cyclosporine and in 48% of patients on steroids and azathioprine) and its severity (21% of cyclosporine-treated patients and 22% of azathioprine-treated patients with symptoms) were similar in both groups. Use of ATG was associated with an increased incidence of CMV disease, especially for patients in the azathioprine group. Both the incidence of CMV disease, and the number of patients with symptoms in the azathioprine group were significantly lower when patients who had received ATG were excluded from analysis. When results were analyzed in just the cadaveric recipients in each group, the incidence and severity of CMV infection tended to be higher in azathioprine-treated patients compared with those maintained on cyclosporine. This could have been explained by the more frequent use of ATG in 84% of azathioprine maintained patients compared with 35% of cyclosporine-treated patients (P less than 0.002) since other factors, such as risk for CMV infection and Solumedrol dose for rejection were similar in both groups. The data demonstrate that ATG has a deleterious influence on the incidence and severity of CMV infection in renal transplant patients, even when the dosage of other immunosuppressive drugs is decreased during ATG therapy. Since patients treated with steroids and azathioprine tend to require ATG to treat steroid-resistant rejection more frequently than do patients on cyclosporine, this effect of ATG must be taken into account when evaluating CMV infection in patients on these two drug regimens.