BACKGROUND:
Pregnant women who are infected with hepatitis B can transmit the disease to their infants and household contacts. The California Perinatal Hepatitis B Prevention Program (CA-PHPP) was initiated in 1991 as a means to identify pregnant hepatitis B carriers and to ensure their infants and household contacts are appropriately immunized.

OBJECTIVE:
To compare the actual number of cases enrolled in CA-PHPP with the expected number of births to HBsAg-positive women by race/ethnicity.

METHOD:
HBsAg seroprevalence estimates from the third National Health and Nutrition Examination Survey (1988-1994) and California Center for Health Statistics natality data were used to estimate expected numbers of births to HBsAg-positive women in California from 2000-2002. Data from CA-PHPP case/household management report forms submitted in 2000-2002 were analyzed in order to compare the demographic profiles of actual versus expected CA-PHPP cases.

RESULT:
8,754 cases were reported to CA-PHPP from 2000-2002, including repeat enrollees. The profile of CA-PHPP enrollees did not change significantly in this time. Compared to program estimates, CA-PHPP identified the minimum expected numbers of pregnant HBsAg-positive Hispanic, African American, white, and U.S.-born Asian/Pacific Islander (A/PI) women. However, the program did not identify the minimum expected number of foreign-born A/PI women. This varied by A/PI ethnicity. For example, while the minimum expected number of Vietnamese cases was identified, only 23.8-26.3% of the minimum expected number of Filipina cases was identified.

CONCLUSION:
Estimating expected numbers is one way to evaluate the effectiveness of CA-PHPP. Seroprevalence estimates for different A/PI ethnicities could provide an even clearer picture of expected CA-PHPP cases. The differences observed between actual and expected numbers in different A/PI populations could be due to under-identification or to actual differences in risk, and merit further investigation.

LEARNING OBJECTIVES:
To understand the strengths and limitations of estimating expected program enrollment numbers.