Kaiser program dramatically cuts vertical hep B transmission

By Megan Brooks

NEW YORK (Reuters Health) - A comprehensive program of prenatal hepatitis B virus (HBV) screening followed by postnatal immunoprophylaxis with hepatitis B immunoglobulin is proving highly effective at preventing perinatal HBV transmission at Kaiser Permanente Northern California, researchers there say.

Their observational study also shows that the highest risk of transmission is in e antigen-positive mothers with very high viral load (>50 million IU/mL).

"This group of women may benefit from additional therapy to prevent vertical transmission. However, for others, the risk of transmission is extremely low as long as the infants are immunized according to the guideline," Dr. Ai Kubo of Kaiser Permanente Division of Research in Oakland, California, who co-led the study with Dr. Lyle Shlager of Kaiser Permanente San Francisco Medical Center, told Reuters Health by email.

The Centers for Disease Control and Prevention (CDC) recommends that pregnant women be screened for HBV and that infants of HBV-positive mothers receive immunoprophylaxis.

"Our findings do support current guidelines in a way that with adherence, the rate of transmission was very low, which is the purpose of the guideline," Dr. Kubo said. "The CDC guideline works for the majority of infants in preventing vertical transmission, if the immunizations are done according to the recommended schedule."

As reported online May 26 in Annals of Internal Medicine, the researchers examined the health records for 4,446 infants born to 3,253 HBV-positive mothers between 1997 and 2010 within Kaiser Permanente Northern California, an integrated health services delivery organization with roughly 3.3 million members.

The infant infection rate was 0.75 per 100 births from 1997 to 2010. Rates per 100 births were 3.37 for e antigen-positive mothers compared with 0.04 for e antigen-negative mothers.

Among mothers with known viral loads, the lowest level associated with transmission was 6.32 x 10^7 IU/mL. Infection rates per 100 births were 3.61 among the 83 births to mothers with viral loads of 5 x 10^7 IU/mL or greater and 0 among the 831 births to mothers with viral loads lower than this level, regardless of e antigen status.

"Until now, nobody has really known who to treat," Dr. Shlager noted in an interview with Reuters Health. "This study identifies the women that are at highest risk for transmitting hepatitis B to their child, who may need a secondary therapy like an oral antiviral medication to lower the viral load of the mother before they deliver to prevent transmission in these very high risk births," he said.

Kaiser Permanente Northern California's Perinatal Hepatitis B Screening Program "case-manages each mother-infant pair (if positive for HepB), enabling the almost complete immunization rate. This is important, as without an organized effort, immunization and follow-up rates can be low, and there is greater chance of transmission," Dr. Kubo said.

"The program has been in effect since 1988 and it has evolved over the years," Dena Lakritz, the program's nurse coordinator, told Reuters Health by phone. "We make sure that every (pregnant) patient has a hepatitis B test . . . We look at all aspects of patient care and don't leave any stone unturned. We interact with all the ob/gyn offices in northern California, the pediatrician offices, and the regional labs."

"The program is very successful and incredibly well-run centrally," Dr. Shlager added.

The study was funded by Kaiser Permanente Community Benefit and the National Institutes of Health.

SOURCE: http://bit.ly/1h9QZAh

Ann Intern Med 2014.