Strategies for Prevention of Varicella Pneumonia: A Cost-Effectiveness Analysis

OBJECTIVE The objective of this study was to compare the cost-effectiveness of 3 strategies of serologic enzyme-linked immunosorbent assay (ELISA) testing and post-exposure varicella zoster immune globulin (VZIG) prophylaxis for the prevention of maternal varicella pneumonia during pregnancy in patients with negative or uncertain histories of varicella infection. METHODS A decision tree was constructed to compare the following strategies: 1) routine serologic testing for varicella immunity followed by targeted post-exposure VZIG prophylaxis, 2) post-exposure serologic testing followed by targeted VZIG prophylaxis, and 3) untargeted post-exposure VZIG administration. The probabilities for the model were obtained from the medical literature and supplemented by expert opinion. The costs were obtained by a review of inpatient hospitalizations for varicella pneumonia. All costs were converted to 1995 dollars. RESULTS Routine serologic testing followed by targeted post-exposure VZIG prophylaxis was the most costly strategy ($37.22/person), with no demonstrable increase in benefit compared with the other 2 strategies. The disutility of this strategy compared with the others was stable across a wide range of values for the probabilities and costs utilized in the sensitivity analysis. We were unable to differentiate between the cost-effectiveness of the other 2 strategies. CONCLUSIONS Routine serologic testing for varicella immunity in patients with negative or uncertain histories of varicella infection should not be performed. The remaining options of screening and prophylaxis appear to be reasonable alternatives for dealing with varicella exposures.