Varicella in the first year after renal transplantation: a report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS).

Prior reports document that children with renal transplants are at risk of severe varicella, with a 5-25% mortality rate. We have examined the current incidence and mortality of varicella requiring hospitalization in pediatric patients in the first year after kidney transplantation through a multi-center retrospective cohort study. Data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) for 2320 pediatric patients who received renal transplants between 1987 and 1993 and were followed until 1995 were examined. Varicella requiring hospitalization in the first post-transplant year occurred in 44 children. Characteristics of the patients who developed varicella were compared to the rest of the NAPRTCS cohort using chi-square analysis. Kaplan-Meier estimates of graft survival were used to compare graft survival in varicella patients and other NAPRTCS patients. Varicella patients tended to be younger (p=0.09) and more often male (p=0.07, chi-square) than other NAPRTCS patients. None of the 44 patients with varicella in their first post-transplant year died from this infection. The number of episodes of acute rejection per transplant and the time to first rejection was not different in patients with varicella compared to the other NAPRTCS patients. Five-year graft survival was not different for varicella cases when compared to other NAPRTCS patients with grafts surviving at least 6 months post-transplant. We conclude that the mortality rate of patients hospitalized with varicella in the first post-transplant year and the risk of subsequent graft dysfunction may be significantly lower than previously described. However, varicella remains a significant cause of potentially avoidable hospitalization in the first post-transplant year. Further study of the safety and efficacy of varicella vaccination in children with renal insufficiency and those post-transplant is warranted.