Vital Signs

Newly Reported Acute and Chronic Hepatitis C Cases — United States, 2009–2018

A. Blythe Ryerson, PhD; Sarah Schillie, MD; Laurie K. Barker, MSPH; Benjamin A. Kupronis, MPH; Carolyn Wester, MD

Disclosures

Morbidity and Mortality Weekly Report. 2020;69(14):399-404. 

In This Article

Methods

National Notifiable Diseases Surveillance System (NNDSS) data for 2009–2018 were analyzed by age group to quantify the annual number of confirmed acute hepatitis C cases per 100,000 population (rate) reported to CDC. During 2016–2019, the Council of State and Territorial Epidemiologists (CSTE) defined a confirmed acute hepatitis C case as one that met both clinical and laboratory criteria, or test conversion criteria. To meet clinical criteria, a person must have been evaluated for discrete onset of any sign or symptom consistent with acute viral hepatitis and have had either jaundice or elevated serum alanine aminotransferase levels. To meet laboratory criteria, the person must have had a positive nucleic amplification test (NAT) for HCV RNA or HCV antigen test. Test conversion is defined as having received a positive anti-HCV test, HCV antigen test, or NAT within 12 months after a negative result for any of these tests. To account for underascertainment and underreporting in acute hepatitis C surveillance data, the total estimated number of cases of acute hepatitis C for 2018 was calculated using standard methodology as described in the CDC viral hepatitis annual surveillance reports.[9,12]

To quantify the number and rate of confirmed chronic hepatitis C cases newly reported to CDC by sex, age, and social generation (i.e., birth cohort), NNDSS data for 2018 were analyzed. In 2018, CSTE defined a confirmed chronic hepatitis C case as one that did not meet the definition of an acute case and had a positive NAT for HCV RNA or HCV antigen test. A newly reported chronic case is a chronic hepatitis C case that meets the CSTE case definition and has not been reported previously.§ All acute and chronic hepatitis C rates were calculated using yearly U.S. population estimates from 2009–2018. The p-values for all chi-squared tests were <0.001 and are not presented.

National Health and Nutrition Examination Survey (NHANES) data were analyzed to estimate the proportion of adults with confirmed current hepatitis C who reported having ever been told that they had hepatitis C. NHANES is an ongoing, nationally representative interview and examination survey of the U.S. noninstitutionalized population.** As part of the 2015–2016 and 2017–2018 surveys, participants were asked whether they had ever been told that they had hepatitis C and were then tested for hepatitis C during an examination (anti-HCV testing followed by reflex NAT testing for HCV RNA). Participants who answered "No" and had positive test results for HCV RNA were considered to be unaware of their infection. Those who refused to answer were classified as missing. Because the number of HCV RNA-positive NHANES participants during any given survey is small (e.g., 50 during 2015–2016 and 51 during 2017–2018), the two survey cycles were combined to improve stability of the estimates. The proportion of HCV RNA-positive persons aged ≥20 years aware of their infection during 2015–2018 was weighted to account for unequal probability of selection and nonresponse, and 95% Clopper-Pearson exact CIs accounted for the complex survey design. SUDAAN (version 11.0.1; RTI International) was used for the analyses. Stratifying the estimate by selected demographic and socioeconomic characteristics was attempted; however, no stratifications of interest met National Center for Health Statistics data presentation standards because of small cell counts.[13]

Complete CSTE case definitions for confirmed acute hepatitis C for 2011, 2012, and 2016 are available at https://wwwn.cdc.gov/nndss/conditions/hepatitis-c-acute.
§The 2016 CSTE definition for confirmed chronic hepatitis C is available at https://wwwn.cdc.gov/nndss/conditions/hepatitis-c-chronic/case-definition/2016.
U.S. population estimates were calculated using the Vintage 2018 Bridge-Race Postcensal Population Estimates available at https://www.cdc.gov/nchs/nvss/bridged_race.htm with states excluded as determined by case reporting status of acute hepatitis C.
**https://www.cdc.gov/nchs/nhanes/index.htm.

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