Preliminary Report of a Nationwide Case-Control Study for Identifying Risk Factors of Tuberculosis Following Renal Transplantation

BackgroundTuberculosis (TB) is an important infection encountered posttransplantation, especially among patients in developing countries, where there are high incidences of morbidity and mortality.Materials and MethodsOne hundred and twenty subjects (1%) from 15 major kidney transplantation centers in Iran from 1984 to 2003 were compared with 440 controls who were matched for operative time, treatment center, and surgical team.ResultsMean ages of research subjects and controls were 38.6 and 36.6 years (P = .04), respectively. The mean duration of pretransplantation hemodialysis was 29 months (range, 2 to 192 months) in research subjects and 20 months (range, 1 to 180 months) in controls (P = .003). Positive past history of tuberculosis was detected in 4 (3.3%) research subjects and in 7 (1.5%) controls (P = .2). Fifty-two research subjects (43.3%) and 241 controls (54.8%) had pretransplantation purified protein derivative of tuberculin less than 5 mm (P = .02). Mean dosages of initial and maintenance immunosuppressive drugs in research subjects and in controls were not significantly different. Sixty research subjects (50%) and 152 controls (34.5%) had rejection prior to diagnosis of TB (P = .03).ConclusionTo our knowledge, this is the first study that demonstrates an increased risk of posttransplant TB by prolonged duration of pretransplant hemodialysis and number of posttransplant rejection episodes. Further study is needed to clarify these findings specifically with respect to various immunosuppressive regimens.