Unknown unknowns for Hepatitis C

[T]here are known knowns; there are things we know that we know.
There are known unknowns; that is to say there are things that, we now know we don’t know.
But there are also unknown unknowns – there are things we do not know, we don’t know.
United States Secretary of DefenseDonald Rumsfeld February 2002

Reading a recent epidemiology article reminded me of the preceding referenced quote  (Hepatology 2012; 55: 1652-61).  This study took a close look at knowledge of being infected with hepatitis C virus (HCV) and what HCV infection may indicate.

The study identified 30,140 participants through the National Health and Nutrition Examination Survey (NHANES) conducted from 2001-2008.  The Centers for Disease Control (CDC) obtains nationally representative data on the health and nutritional status of noninstitutionalized civilians across the U.S.  NHANES uses a ‘complex, stratified, and mulitstage probability sampling design and collects information from approximately 5,000 persons per year using standardized household interviews, physical examinations, and testing of biologic samples.’

Participants 6 years of age or older who tested positive for anti-HCV antibodies were sent a report.  Out of the 30,140 participants, 393 (1.4%) had evidence of past or current HCV infection; 170 were available for the study investigators.  Only 49.7% were aware of HCV status prior to receiving NHANES letter.  Furthermore, only 3.7% were first tested for HCV because they or their doctor thought they were at risk for infection; most were tested as part of a routine exam (perhaps detected after elevated ALT values) (46.7%), due to symptoms (15.9%), or blood donation (9.7%).

Another aspect of the study was determining the participants’ understanding of HCV infection.  Correct responses to the HCV survey were more likely in individuals between 40-59 years of age, white non-Hispanics, and patients who had seen a doctor about their HCV infection.  Specific questions often answered incorrectly included the following:

  • whether HCV could be contacted by kissing –only 68% knew this was false
  • whether HCV could be transmitted sexually –only 64% knew this was true
  • whether HCV could be acquired during birth if mother had HCV –only 57% knew this was true

Take home points:

  • Risk-based screening for HCV will continue to fail.  Physicians may not elicit adequate information and patients may deny risky behaviors even if asked.
  • Approximately half of patients in this cohort were unaware of HCV infection.
  • Many misconceptions about HCV persist even among those who had received counseling.

Related blog posts:

Pediatric HCV Guidelines

HCV now more deadly than HIV

The cost of progress in treating Hepatitis C

Additional resource:

http://www.cdc.gov/hepatitis/RiskAssessment/  This website allows individuals to assess their risk for hepatitis.