What is the purpose of HepVu.org?
HepVu was developed with the goal of making Hepatitis C (HCV) data widely available and locally relevant. HepVu’s data can help inform decisions about the best use of hepatitis C prevention, testing and treatment resources. These data also underscore the importance of testing for certain high-risk groups.
Where does the HepVu data come from?
State-level Hepatitis C antibody prevalence estimates were derived from the Coalition for Applied Modeling for Prevention (CAMP) at Emory University, a project supported by the Centers for Disease Control and Prevention (CDC). State-level Hepatitis C mortality data were obtained from the National Vital Statistics System (NVSS) and compiled by researchers at the Rollins School of Public Health at Emory University. All data received by Emory University are anonymous, meaning that no names or other personally identifying information are provided.
What is a Hepatitis C antibody?
An antibody is a substance found in the blood that the body produces in response to a virus. Having a positive Hepatitis C antibody test means that a person was exposed to the virus at some time in his or her life. If the antibody test is positive, a doctor will most likely order a second test to confirm whether the virus is still present in the person’s bloodstream. 15-25 percent of people exposed to Hepatitis C will clear the virus from their bodies and not develop chronic infection. HepVu.org antibody prevalence estimates are based on the number of people who have evidence of exposure to Hepatitis C, as this is the best indicator of the overall epidemic and informs public health strategies to address the epidemic.
What does HepVu show?
HepVu provides interactive maps that illustrate Hepatitis C antibody prevalence estimates and mortality data at the state level. Data can be visualized by rates and cases, and mortality data can be stratified by sex, race, and age. The state-level antibody prevalence estimates on HepVu are based on the National Health and Nutrition Examination Survey (NHANES), which uses a complex sampling design to estimate the number of past and current Hepatitis C infections in the U.S. by testing a smaller representative sample. The Emory CAMP team then used small-area estimation techniques to allocate the national number of estimated infections to each state. State-level Hepatitis C mortality data are obtained from the National Vital Statistics System (NVSS).
What does HepVu not show?
The state-level Hepatitis C antibody prevalence estimates are rooted in data from the National Health and Nutrition Examination Survey (NHANES), which only samples non-institutionalized adults and therefore excludes incarcerated persons, homeless persons and those in active military service.
We aggregated data across multiple years to produce stable estimates of the underlying antibody prevalence of Hepatitis C. As a result, our data sources are likely less representative of populations of persons infected in recent years. Incidence of HCV infection has been increasing since 2010, largely due to an increase in injection drug use associated with the opioid epidemic. Nationally, the number of recent new infections is small relative to the prevalent population, although some states have had larger increases than the national trends.
Why are there data delays?
HepVu publishes the latest mortality data available. There are delays in the reporting of the mortality data due to the time it takes to collect the information and make corrections if necessary. HepVu uses and reports the most recent existing data possible provided by the National Vital Statistics System.
What does HepVu demonstrate about Hepatitis C in the U.S.?
HepVu provides a comprehensive visual overview of the Hepatitis C epidemic across the U.S. The interactive maps illustrate geographic variations in the epidemic, and how the epidemic affects different communities. This information is intended to help individuals understand how Hepatitis C affects their communities, and allows health officials and policymakers to see where prevention and care programs are needed most.
- The Western U.S. had the highest rate of people with evidence of Hepatitis C infection, with 10 of the region’s 13 states having an estimated Hepatitis C antibody prevalence rate above the national average of 1,670 Hepatitis C cases per 100,000 persons (2010).
- Eight states—California, Texas, Florida, New York, Pennsylvania, Tennessee, Ohio and Washington—make up more than 50% of all persons living with evidence of Hepatitis C infection (2010).
- The estimated antibody prevalence rate of Hepatitis C among adults in each state ranged from 0.71% (Illinois) to 3.34% (Oklahoma).
- There were an estimated 1.56 million persons with evidence of Hepatitis C infection in the South, the highest of any region (2010).
- American Indians/Alaskan Natives in California have the highest antibody rate of Hepatitis C related deaths of all races in any state at 31 deaths per 100,000.
Why does the map differ between rate and number of cases?
The scales in the legends for rates and cases differ because the rate (expressed as the number of cases per 100,000 people in the population) is an expression of the relative concentration of estimated people with Hepatitis C or deaths related to Hepatitis C in an area (state). Rates differ from the number of cases, which is the actual number of estimated past or current cases or deaths that occurred in people who had Hepatitis C. Infection rates can be useful for comparing the severity of the Hepatitis C epidemic in areas with different population sizes – such as comparing densely populated areas to a more sparsely populated one. The number of cases can identify areas where the greatest or fewest number of people estimated to have Hepatitis C live, or where Hepatitis C deaths have occurred.
For example, in a state with fewer people, but with a relatively large mortality rate, the state may be shaded a dark purple when viewing the mortality rate. However, the same state may not appear dark purple when viewing the map by the total number of cases because the state has a smaller number of cases compared with other states.
Do you intend to update HepVu data?
Mortality data will be updated on a yearly basis. We plan to update the antibody prevalence estimates, and add new data features and greater geographic detail when new data are available.
What is "Powered By AIDSVu"?
Powered By AIDSVu projects use the existing AIDSVu (AIDSVu.org) infrastructure to expand to other projects that visualize complex information to inform public health actions. Powered By AIDSVu incorporates collaborative content and programs from additional data sources and partners.
Why is Hepatitis C antibody prevalence an estimate and not the actual number?
Although viral hepatitis is a reportable condition to the National Notifiable Diseases Surveillance System (NNDSS), most viral hepatitis infections are asymptomatic and not all cases are identified or reported. As a result, Hepatitis C surveillance is incomplete and the precise number of cases are not able to be counted.
The state-level estimates on HepVu are based on the National Health and Nutrition Examination Survey (NHANES), which uses a complex sampling design to estimate the number of Hepatitis C infections in the U.S. by testing a smaller representative sample. The Emory CAMP team then used small-area estimation techniques to allocate the national number of estimated infections to each state. A small degree of statistical error is expected in all estimation approaches, but this approach provides a systematic and robust method for quantifying Hepatitis C infection in all 50 states and Washington D.C.
The Hepatitis C antibody prevalence estimates for each state show a range. What does that mean?
The range around each estimate is the 95% confidence interval. These intervals represent statistical uncertainty in the antibody prevalence estimates that are created during the estimation process. The interpretation of the range is that we are 95% confident from the data we used that the actual prevalence estimate would fall within this range. Confidence intervals are commonly used when you are not able to directly count the number of cases and must use estimation methods. More details about the methods used for the Hepatitis C antibody prevalence estimates are in the paper published in Clinical Infectious Diseases
What is a model and how was it used to create the Hepatitis C antibody prevalence estimate?
A model is a mathematical process that aims to predict or describe the dynamics in a system as accurately as possible using collected information (i.e. data). This approach uses a model to predict the Hepatitis C antibody prevalence rates in each of the 24 demographic strata in each state. The mortality data used to inform the model is quite robust, and this model predicted antibody prevalence rates that were very close to the observed rates in each stratum.
My state reports a different number of people living with Hepatitis C infection than HepVu. Why is that?
Many states have their own unique methods for quantifying the number of Hepatitis C infections in their state. Estimates on HepVu represent non-institutionalized persons 18 years of age or older. Some states try to also estimate and include the number of infections among populations that are not included in NHANES sampling (homeless, incarcerated, hospitalized, etc.) Also, methods based on locally available surveillance data may generate different results. As a result of the variability in approaches and data sources among individual states, it is difficult to compare results across jurisdictions. The systematic nature of the antibody prevalence estimates on HepVu provide an opportunity to quantify and compare the Hepatitis C burden across all 50 states and Washington D.C.
Where can I go to get more information about the methods for the antibody prevalence estimates?
State-level Hepatitis C antibody prevalence estimates were derived from an Emory University Coalition for Applied Modeling for Prevention (CAMP) modeling project, “Estimation of State-level Prevalence of Hepatitis C Virus Infection, US States and District of Columbia, 2010,” which was published in the peer-reviewed journal Clinical Infectious Diseases. Click here to read the paper.
There has been a large increase in injection drug use in my state over the last year. Is this reflected in the antibody prevalence estimate?
The antibody prevalence estimates on HepVu are calculated using data from 1999-2012, and can be thought of as a rough average over that period. Therefore, the antibody prevalence estimates may not be as sensitive to short term changes in Hepatitis C incidence rates. Given the large number of people already living with Hepatitis C, the impact of recent changes in behavior (such as injection drug use) is better understood by looking at incidence rates.
Why do the antibody prevalence estimates say 2010 and the mortality data say 2014?
The antibody prevalence estimates are calculated using several years (1999-2012) of NHANES data on Hepatitis C infection, but the population totals from the 2010 U.S. Census data were used to determine HCV antibody prevalence in each state in 2010. The National Vital Statistics System mortality data are from 2014.
Why does HepVu primarily focus on Hepatitis C?
The 2017-2020 National Viral Hepatitis Action Plan has brought national attention to the urgent need to address viral hepatitis. At present, the best available data pertains to Hepatitis C. However, as the Action Plan notes, surveillance on all types of Hepatitis is severely limited by a lack of comprehensive data. As a Powered by AIDSVu platform, HepVu seeks to use the highest quality data to inform public policy. Emory University’s “Estimation of State-level Prevalence of Hepatitis C Virus Infection, US States and District of Columbia, 2010,” published in the peer-reviewed journal Clinical Infectious Diseases, offers the most up-to-date standardized state-level Hepatitis C antibody prevalence rate estimates. This is an initial start in developing HepVu with the thought that other Hepatitis prevalence data will become available for mapping on HepVu in the future.