Cost-Effectiveness of Universal Compared With Voluntary Screening for Human Immunodeficiency Virus Among Pregnant Women in Chicago
Authors: Immergluck Lilly Cheng , Cull William L. , Schwartz Alan , Elstein Arthur S. 
Published: August 2004

Objectives.
To determine and compare the cost-effectiveness of implementing 3 screening strategies to detect human immunodeficiency virus (HIV) infection among pregnant women in Chicago, Illinois: no screening, voluntary screening, and universal screening.

Methods.
A decision-analysis model was developed, using standard cost-effectiveness analysis from a societal perspective. Reference case estimates were derived from a surveillance project conducted by the Illinois Department of Public Health and studies were published in the medical literature. Costs included direct and indirect medical costs associated with identification of pregnant women infected with HIV and identification, prevention, and treatment of perinatally HIV-infected newborns. Specifically, for each screening option, the cost per pregnant woman screened, the resulting number of pediatric HIV infections, and the number of newborn life-years were calculated. All costs were adjusted to the 1997 dollar value and discounted at 3%. Sensitivity analyses were determined for all variables included in the decision model.

Results.
The estimated prevalence of HIV infection among pregnant women in Chicago is .41%. For every 100 000 pregnant women, it is estimated that 104.6 children would be infected with HIV if no screening strategy were implemented and 44.8 children would be infected if voluntary HIV testing (assuming a 92.7% acceptance rate) were available. In comparison, if universal HIV testing was performed, the number of children infected with HIV would decrease to 40 cases. Sensitivity analysis across a maternal HIV prevalence rate of .01% to 2.2% found that universal screening would be cost-saving in communities where the seroprevalence is .21%. In Chicago, it would take an estimated 5.2 months of screening pregnant women to avert 1 case of pediatric HIV. Taking into consideration the lifetime costs of treating a child with HIV infection, universal HIV testing of 100 000 pregnant women would result in a cost-savings of $3.69 million when compared with no screening, and $269 445 when compared with voluntary screening. We estimated that it would cost $11.1 million to screen 100 000 pregnant women in Chicago. The cost-savings produced with increased screening are the direct result of reduced cases of newborns infected with HIV. A 2-way sensitivity analysis was performed to examine how costs vary as a function of the voluntary rates for HIV-positive and HIV-negative women. When screening falls below 50% for HIV-positive mothers, universal screening becomes cheaper than voluntary screening even if no HIV-negative mothers were screened.

Conclusion.
Reference case analyses showed that universal HIV screening of pregnant women in Chicago would both decrease the number of HIV-infected newborns and save money in comparison to voluntary or no testing strategies. Sensitivity analysis was robust across all variables for the conclusion that universal screening was more effective than voluntary screening. For many communities that have HIV prevalence rates for mothers of &gt;.21%, universal screening would also save money in comparison to voluntary screening. For communities with prevalence rates &lt;.21%, the benefits of universal screening may outweigh the costs for screening as we found that desirable incremental cost-effectiveness ratios were found for prevalence rates as low as .0075%.