Management of the presumed susceptible varicella (chickenpox)-exposed gravida: a cost-effectiveness/cost-benefit analysis.

OBJECTIVE To compare the cost-effectiveness and cost-benefit of different strategies for managing the presumed susceptible varicella (chickenpox)-exposed gravida. METHODS Three strategies were evaluated: 1) a do-nothing or observation strategy; 2) a testing strategy, in which immune status was assessed and varicella-zoster immune globulin was administered to those who tested nonimmune; and 3) a universal-administration strategy, in which varicella-zoster immune globulin was given to all exposed, presumed susceptible gravidas. Because precise data are unavailable about varicella mortality and hospitalization rates in pregnancy, a range of potential rates was evaluated, from one to greater than 20 times healthy nonpregnant adult rates. The potential efficacy of varicella-zoster immune globulin varied from 1 to 99%. A strategy was defined as cost-effective if it cost less than $50,000 per life-year gained. RESULTS If the mortality rate from varicella infection in pregnancy was increased fivefold over the nonpregnant healthy adult rate (ie, from 31/100,000 to 155/100,000 cases), efficacy would have to be at least 49% for the immune-testing strategy to be cost-effective. If pregnancy only doubled the varicella mortality rate, then even with perfect efficacy, the immune-testing strategy would not be cost-effective. Under most assumptions, the universal-administration strategy was cost-ineffective when compared with the immune-testing strategy. Similar results were obtained in the parallel cost-benefit analysis, which considered hospitalization costs and rates. The analysis was sensitive to the varicella transmission rate and the discount rate. CONCLUSION From a cost-effectiveness/cost-benefit standpoint, management based on immune testing is preferable to universal varicella-zoster immune globulin administration when caring for the varicella-exposed gravida with a negative or indeterminate infection history.