Hepatitis C Antibody Prevalence Estimates
The state-level Hepatitis C antibody prevalence estimates presented on HepVu were obtained from the Coalition for Applied Modeling for Prevention (CAMP) at Emory University. These estimates were calculated using three publicly available data sources – National Health and Nutrition Examination Survey (NHANES), National Vital Statistics System (NVSS), and U.S. Census data – intercensal data (1999-2012) and 2010 data.
Weighted sampled NHANES data represent all non-institutionalized people 6 years of age and older residing in the 50 states and the District of Columbia (DC). Demographic information and blood specimens are collected by the NHANES. For the CAMP analysis, persons with confirmed positive anti-HCV antibody results were considered to have prevalent Hepatitis C virus infection. Data from eight NHANES cycles were used, representing a 14-year span (1999-2012). NHANES responses were grouped by demographic information. Sex was categorized into male and female. Race/ethnicity was categorized into Hispanic, non-Hispanic white, non-Hispanic black, and other (including multi-racial). Age was categorized into three birth cohorts – before, during, and after 1945-1965.
The NVSS data are collected using information from death certificates of all U.S. residents within the 50 states and DC. Deaths of residents of Puerto Rico, other U.S. territories, and fetal deaths are not included. Demographic, geographic, and cause-of-death information for each individual is recorded. Any records that included the ICD-10 code for acute viral Hepatitis C (B17.1) or chronic viral Hepatitis C (B18.2) as the underlying or multiple cause of death were used to identify deaths related to Hepatitis C.
The U.S. Census Bureau produces demographic and geographic data through decennial censuses, annual surveys, and population estimates and projections. Annual intercensal population estimates datasets were used to provide denominators for HCV mortality rates for each year during 1999-2012. State-by-demographic group population totals from the 2010 U.S. Census were used in calculations to determine HCV antibody prevalence in each state in 2010.
The HCV antibody prevalence estimates analysis was restricted to people aged 18 years of age or older, living within the 50 states and DC. The NHANES data were used to calculate direct weighted estimates of national HCV-antibody prevalence in 24 strata formed by levels of sex (2), race/ethnicity (4), and birth cohort (3). The 2010 U.S. Census data were stratified by the same 24 strata within each state. These state-by-strata population totals were multiplied by the stratified HCV-antibody prevalence estimates to generate crude state-level estimates (adjusted for sex, race, and age). NVSS mortality data and intercensal population totals were used to model the HCV-related death rate in the same 24 strata within each state. The state-by-strata HCV-related death rates were then compared to the national HCV-related death rate in each strata, to create a ratio of state-by-demographic group stratum effects. The state effects ratios were multiplied by the crude state-level antibody prevalence estimates to generate mortality-adjusted HCV antibody prevalence totals in each strata in each state. These were summed across strata and combined with 2010 US Census population data to generate the HCV antibody prevalence estimates in each state.
Rates are expressed as the number of estimated cases per 100,000 people in the population, rounded to the nearest ten persons. It is an expression of the relative concentration of estimated people with Hepatitis C in an area (state). Estimated cases are rounded to the nearest hundred persons.
The range around each estimate is the 95% confidence interval. These intervals incorporate the joint statistical uncertainty of the stratified NHANES prevalence estimates in each demographic group and the modeled Hepatitis C mortality rates. The 95% confidence intervals were constructed using a Monte Carlo simulation with 10,000 runs that resampled values from those two original distributions.
A more detailed description of the HCV antibody prevalence estimation method is available in the peer-reviewed publication available at academic.oup.com.
Hepatitis C Mortality Data
HepVu’s state-level Hepatitis C mortality data were obtained from the National Vital Statistics System and compiled by researchers at the Rollins School of Public Health at Emory University. The NVSS data are collected using information from death certificates of all U.S. residents within the 50 states, DC, and Puerto Rico. Deaths of residents of other U.S. territories and fetal deaths are not included. Demographic, geographic, and cause-of-death information for each individual is recorded. Any records that included the ICD-10 code for acute viral Hepatitis C (B17.1) or chronic viral Hepatitis C (B18.2) as the underlying or multiple cause of death were used to identify deaths related to Hepatitis C.
Case counts represent Hepatitis C-related deaths of U.S. residents that occurred in the 50 states and in DC. Rates were calculated by using the 2010 US Census population data and are expressed as the reported number of Hepatitis C-related deaths during the calendar year per 100,000 population. Rates generated from a small number of cases should be interpreted with caution. If the death count for any particular group/state is less than 20, rate data are suppressed and appear as no color (white) on the maps.
HepVu allows viewers to look at Hepatitis C antibody prevalence estimates and mortality data at the overall state-level for cases and rates. The mortality data are also able to be stratified by sex, race, and age groups. Sex is displayed as male or female. Race is displayed as non-Hispanic American Indian, non-Hispanic Asian, non-Hispanic Black/African American, non-Hispanic White, and Hispanic/Latino. Non-Hispanic Pacific Islander was also included, but no cases were reported. Age is displayed as three birth cohorts – younger than Baby Boomers (0-49), Baby Boomers (50-69), and older than Baby Boomers (70+).
Displayed Legend Values
Legend values were developed by calculating deciles in SAS analytic software (SAS Institute, Cary, NC) and rounding to create the legend values for each group. In order to illustrate the variation in rates and case counts, values were developed specific to each demographic grouping (i.e., overall, and separately by sex, by race, and by age group). Thus, a total of 8 map scales exist (rate/case count by overall/sex/race/age group) for the mortality data, and 2 map scales exist for the antibody prevalence estimates (overall estimated rate/case count). Because the ranges that produce the map colors may differ, users should be careful in comparing maps between demographic categories (sex, race, and age group).
|Data Element||Location on HepVu||Data Source||Anticipated Update Frequency on HepVu Website|
|Estimated Rates and Case Counts of Persons Living with HCV, State Data||Maps||National Vital Statistics System; Data Request, July 2016.||When Available|
|2010 Population||Profile||U.S. Census Bureau, 2010 Census.||When Available – Annuall|
|Drug Overdose Mortality||Profile||Centers for Disease Control and Prevention. National Center for Health Statistics. Health Indicators Warehouse. www.healthindicators.gov. September 2016.||When available|