To estimate the potential economic benefit of reduced indirect antiglobulin screening for Rh(D)-negative pregnant women.
A chart review of all Rh(D)-negative mothers delivering at the University of Washington from 2002 to 2012 was conducted to determine the rate of gestational seroconversion to anti-D antibodies before 28 weeks of gestation. A decision tree was constructed to estimate the economic effects of eliminating the indirect antiglobulin screen at 28 weeks of gestation and instead immunizing all Rh(D)-negative, anti-D antibody-negative women with anti-D immune globulin at that time. A theoretical cohort of 100,000 women was modeled. Probabilities and costs were derived from published literature, chart review, and expert opinion. Univariate sensitivity analyses followed by a Monte Carlo analysis examined assumptions and uncertainties in our model across entire distributions.
The seroconversion rate of development of anti-D antibodies before 28 weeks of gestation in the cohort analyzed was 0.099% (2/2,029 women). From a societal perspective, the expected cost savings from implementing the reduced indirect antiglobulin screening strategy, per 100,000 women, ranged from $6 to $7.7 million. The overall cost savings for implementing this strategy in the United States for 1 year ranged from $34.7 to $35.6 million. This strategy remained cost-beneficial when varying our parameters (eg, anti-D immune globulin, antibody test cost) to their logical extremes. The Monte Carlo analysis verified the cost savings of our strategy.
The updated seroconversion rate and our model suggest that eliminating the 28-week antibody screen would be cost-beneficial from a societal perspective while posing minimal potential harm to the recipients.