Infection by the hepatitis C virus in chronic renal failure patients undergoing hemodialysis in Mato Grosso state, central Brazil: a cohort study

BACKGROUND Hepatitis C virus (HCV) is a significant problem for patients undergoing hemodialysis therapy. This situation has never been studied in Mato Grosso state, central Brazil. This study was conducted aiming to estimate the prevalence of the anti-HCV and the incidence of seroconversion in the main metropolitan region of the state. METHODS 433 patients from the six hemodialysis units were interviewed and anti-HCV was tested by a third-generation enzyme immunoassay. An open cohort of patients who tested negative for anti-HCV at the entry of the study was created and seroconversions was assessed monthly. The staff responsible for the units were interviewed to assess whether the infection control measures were being followed. Logistic and Cox regression analysis were performed in order to assess risk factor to HCV. RESULTS The entry on the study took place between January 2002 and June 2005. 73 out of 433 (16.9%, CI 95%: 13.3-20.8) was found to be anti-HCV reactive. The multivariate analysis indicated as risk factors associated to anti-HCV the duration of the hemodialysis treatment, the number of transfusions received, and the unit of treatment. An open cohort of 360 patients who tested negative for anti-HCV was created, with a following average of 24 (+/- 15) months. Forty seroconversions were recorded corresponding to an incidence density of 4.6/1000 patient-months, ranges 0 to 30 among the units. Cox regression indicated the time of hemodialysis (RR = 2.2; CI 95%: 1.1-4.6; p < 0.05) and the unit where treatment was performed (RR = 42.4; CI 95%: 9.9-180.5; p < 0.05) as risk factors for seroconversion. The three units with highest anti-HCV prevalence and incidence were identified as those that more frequently failed to apply control measures. CONCLUSION The study demonstrated high prevalence and incidence of anti-HCV in some of the hemodialysis units. Time on hemodialysis therapy was an independent factor associated to HCV. Blood transfusion was associated with anti-HCV in initial survey but was not important in incident cases. Failure of applying control measures was more evident in units with the highest HCV prevalence and incidence. The results suggest that nosocomial transmission was the main spread factor of HCV in the studied population.