What is the purpose of HepVu.org?
HepVu was developed by Emory University’s Rollins School of Public Health in partnership with Gilead Sciences, Inc. to help public health practitioners better understand the scope and health consequences of viral hepatitis in the United States. It is led by Dr. Patrick Sullivan, Professor of Epidemiology, along with stakeholders from the community, departments of public health, providers, and other academic partners.
Where does the HepVu data come from?
State-level Hepatitis C chronic and antibody prevalence estimates were obtained from the Coalition for Applied Modeling for Prevention (CAMP) at Emory University, a project supported by the Centers for Disease Control and Prevention. State-level Hepatitis C mortality data were obtained from the WONDER online database system developed by the Centers for Disease Control and Prevention (CDC). Data were compiled by researchers at the Rollins School of Public Health at Emory University. HepVu publishes the latest Hepatitis C data available. 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 maps Hepatitis C chronic and antibody prevalence estimates, as well as Hepatitis C -related mortality data at the state-level. HepVu is interactive and data can be visualized by rates and cases, as well as stratified by sex, race, and age. Social determinants of health are also available to be viewed as side-by-side comparisons.
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 visualization of the Hepatitis C epidemic across the United States. The interactive maps illustrate geographic variations in the epidemic, and how the epidemic affects communities differently. This information is important for individuals to understand Hepatitis C in their communities, and for health officials and policymakers to see where prevention and care programs are needed most.
- The HepVu maps illustrate the considerable geographic variations in Hepatitis C estimates mortality across the United States.
- The maps of the Hepatitis C estimates show high rates of people living with Hepatitis C in the Western and Southwestern areas of the United States compared to much of the rest of the country.
- The mortality data on HepVu’s maps can be viewed by different demographic filters. HepVu shows that Hepatitis C mortality rates are higher for males than females, higher for the Baby Boomer age group (50-69 years old) compared to those younger and older, and higher in white and black compared to other races.
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 people with Hepatitis C or deaths that occurred in people who had Hepatitis C. The 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 number of people with Hepatitis C who died, 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 are planning to update the Hepatitis C 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 are the Hepatitis C chronic and antibody prevalence data estimates 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, 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 exercises, 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 particular approach uses a model to predict the Hepatitis C -related chronic and antibody prevalence rates in each of the 18 demographic strata in each state. The mortality data used to inform the model are quite robust and this model predicted 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. It is important to remember that the 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 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?
The paper with descriptions of the methodology can be viewed here.
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 chronic and antibody prevalence estimates on HepVu are calculated using data from 1999-2012 and can be thought of as a rough average over that time period. Therefore, the prevalence estimates may not be as sensitive to short term changes in Hepatitis C incidence rates. Given the large number of people who already have Hepatitis C infection, the impact of recent changes in behavior (such as injection drug use) is better understood by looking at incidence rates.
Why use 2006-2010 ACS data for population estimates?
NHANES uses data from the American Community Survey (ACS) to calculate weights and population totals. NHANES is a national representative survey of the civilian noninstitutionalized U.S. population and ACS population totals can be used to estimate population totals (stratified by state and demographic group) for this population by excluding respondents in institutionalized group quarters. The 2006-2010 5-year ACS estimates include data collected continuously over the entire time period, which results in a sufficient sample size to calculate reliable estimates at small geographies.
Why do the chronic and antibody prevalence estimates say 2010 and the mortality data say 2016?
The Hepatitis C estimates are calculated using data from several years, but the population totals from the 2006-2010 American Census Survey (ACS) data were used to determine HCV prevalence in each state in 2010. The National WONDER mortality data are from 2016.
Why does HepVu primarily focus on Hepatitis C?
With the publication of the paper Estimation of State-level Prevalence of Hepatitis C Virus Infection, US States and District of Columbia, 2010 by E. Rosenberg et al., Hepatitis C prevalence data for mapping purposes was made available. The publication of the paper Estimates of state-level chronic Hepatitis C virus infection, stratified by race and sex, United States, 2010 by E. Hall et al., the CAMP team has expanded their analyses to include the chronic estimates, which have now been added to HepVu. These are initial starts to developing HepVu with the thought that other Hepatitis data will become available for mapping on HepVu in the future.