Case-control study of hepatitis B and hepatitis C in older adults: healthcare exposures contribute to burden of new infections

Background: In the United States, unsafe injection practices and other infection control breaches are associated with the transmission of hepatitis B virus (HBV) and hepatitis C virus (HCV) in the context of outbreaks.

Objective: To examine the contribution of healthcare exposures to sporadic cases of acute hepatitis B and hepatitis C reported as part of national hepatitis surveillance.

Methods: We conducted a case control study to examine risk factors for sporadic acute hepatitis B and hepatitis C at 3 sites (New York City, the rest of New York State, and Oregon) that conduct enhanced surveillance for viral hepatitis. Confirmed cases occurring in persons aged ≥ 55 years from 2005-2007 were eligible for enrollment. Nursing home residents and cases identified as a result of outbreak investigations were excluded. Potential controls were identified using telephone and address directories and were matched to cases by age group (55-59 years, 60-69 years, and ≥70 years) and ZIP code of residence. Data including behavioral and healthcare-related exposures that occurred in the 6 months prior to symptom onset (cases) or prior to the date of interview (controls) were collected from consenting study participants via telephone interviews. Stratified univariate and multivariate analyses of the matched risk factor data were performed.

Results: Forty-eight (37 hepatitis B; 11 hepatitis C) case- and 159 control-patients were enrolled. Males were over-represented among cases (67%) compared with controls (39%; p< 0.001). Fourteen (29%) cases reported sexual or household contact with an HBV or HCV patient (n=4; 8%) or high risk personal behaviors such as >1 sex partner during the previous six months (n=8 [7 hepatitis B cases]; 17%). Cases were more likely than controls to report multiple sex partners (p<0.001). Other variables that were significantly associated (p<0.05) with case status in univariate analyses included: hemodialysis (8% of cases exposed during the six months prior to infection); injections in a healthcare setting (excluding vaccinations; 59%); and surgery (33%).  Multiple sex partners (aOR=40.4, 95% confidence interval [95%CI] 4.6-356), injections (aOR=2.9, 95%CI 1.3-6.3) and dialysis (aOR=17.7, 95%CI 1.8-178) were associated with infection in a multivariate model controlling for gender. Similar results were obtained when the analysis excluded hepatitis C cases or included available information from medical chart reviews.

Conclusions: Healthcare exposures likely represent an important but overlooked source of sporadic HBV and HCV infection among older adults. Our findings underscore the need for hepatitis B vaccination of persons at risk for infection, enhanced viral hepatitis surveillance, increased support for health departments to investigate possible cases, and stronger oversight of infection control procedures in healthcare facilities.