Table of Contents

Component Description

Hepatitis viruses constitute a major public health problem because of the morbidity and mortality associated with the acute and chronic consequences of these infections. New immunization strategies have been developed to eliminate the spread of hepatitis B virus (HBV) and hepatitis A virus (HAV) in the United States. Recommendations have also been developed for the prevention and control of hepatitis C virus (HCV) infection. Because of the high rate of asymptomatic infection with these viruses, information about the prevalence of these diseases is needed to monitor prevention efforts. By testing a nationally representative sample of the U.S. population, NHANES will provide the most reliable estimates of age-specific prevalence needed to evaluate the effectiveness of the strategies to prevent these infections. In addition, NHANES provides the means to better define the epidemiology of other hepatitis viruses. NHANES testing for markers of infection with hepatitis viruses will be used to determine secular trends in infection rates across most age and racial/ethnic groups, and will provide a national picture of the epidemiologic determinants of these infections.

In 2013, CDC revised its guidelines for Hepatitis C (HCV) testing because of following: 1) changes in the availability of certain commercial HCV antibody tests; 2) evidence that many persons who are identified as reactive by an HCV antibody test might not subsequently be evaluated to determine if they have current HCV infection; and 3) there have been significant advances in the development of antiviral agents with improved efficacy against HCV.1 This new guidance was adopted beginning in the NHANES 2013-2014 cycle. Among persons aged 6 years and older who participated in NHANES during the 2013–2014 and 2015-2016 cycles, antibody confirmation testing was conducted using a 3rd generation commercial line immunoassay test for the subset of participants whose serum was reactive using a hepatitis C virus (HCV) antibody screening procedure, subsequently found to be negative for HCV RNA. In NHANES 2013-2014 cycle and 2015, only stored serum samples were analyzed. In 2016, serum samples were analyzed from all eligible participants during the 2016 NHANES.

For these reasons, use of 2013 and later data for comparisons or trending with data from 2012 and earlier is not advised.

The new Hepatitis C algorithm flow chart can be found in the laboratory method file and/or by following the MMWR link below:

https://www.cdc.gov/mmwr/pdf/wk/mm62e0507a2.pdf

Beginning in the 2017-2018 cycle, the HCV confirmatory antibody test (INNO-LIA) will be released in the HEPC dataset with HCV RNA and Genotype data.

Eligible Sample

Participants aged 6 years and older who participated in NHANES 2015, had stored sera, and were both HCV antibody screening reactive and HCV-RNA negative were eligible.

Description of Laboratory Methodology

Hepatitis C Confirmed Antibody (INNO-LIA)

In 2012 and earlier years, the hepatitis C virus testing algorithm began with an antibody screening test, and antibody screening reactive samples were then tested with a recombinant/synthetic immunoblot assay as the antibody confirmation test. Samples with positive antibody confirmation results were then tested with a nucleic acid amplification test for hepatitis C virus RNA. HCV-RNA positive samples were then tested with a line probe assay to determine the virus genotype from six genotypes, and subtype for genotype 1, the most prevalent genotype in the US. Beginning in 2013, samples reactive to the antibody screening test were first tested for RNA. Then, all RNA positive samples were tested for genotype, and only RNA negative samples were tested with an antibody confirmation test. This change in the testing algorithm was made to align the NHANES HCV testing algorithm with a 2013 update to CDC’s guidance on testing for HCV infection by clinicians and laboratorians. Additionally, the antibody confirmation test changed to a 3rd generation line immunoassay in 2013 because the test used in 2012 and earlier was no longer commercially available and the stored supply of these test kits had been exhausted.

For the antibody confirmation test, the manual 16-hour sample incubation test procedure is used. 10ul of specimens and controls are diluted in 1mL diluent in test troughs to ensure test strips will slide easily and remain submerged during incubation. Specimens and controls are incubated with agitation by rocker at 34 rpm overnight (16±2 hours) at room temperature (18–25°). After a 3X/5min each wash step on microtiter plate shaker, conjugate is added with a 30-minute incubation at room temperature, followed by aspiration, 3X/5min each wash step and 30-minute incubation in substrate solution also on microtiter plate shaker. Finally, strips are agitated with stop solution for 10–30 minutes at room temperature. The microtiter plate shaker is set for 160 rpm and used for all the washes and solution incubations. Strips are then dried completely in a dry incubator at 37°C for 30 minutes then mounted on the line immunoassay score data reporting sheet with inverted tape for reading within one hour using the reading card. The strips have lines for a background control, three reference lines for antibody (level ±, human IgG, weak positive; level 1+ human IgG, moderate positive; and level 3+, anti-human Ig, strong positive), and six lines for HCV antigens (C1, C2, E2, NS3, NS4, and NS5). Samples with a positive antibody confirmation test result are reported as positive. Samples with a negative antibody confirmation test result are reported as negative. Samples with an indeterminate antibody confirmation test result are released as missing. Only specimens insufficient in quantity are deemed indeterminate.

There were no changes to the lab method, lab equipment, or lab site for this component in the NHANES 2015-2016 cycle.

Laboratory Method Files

Laboratory Quality Assurance and Monitoring

Serum samples were processed, stored, and shipped to the Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA for analysis.

Detailed instructions on specimen collection and processing are discussed in the NHANES Laboratory Procedures Manual (LPM). Vials are stored under appropriate frozen (–30°C) conditions until they are shipped to Division of Viral Hepatitis, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention for testing.

The NHANES quality assurance and quality control (QA/QC) protocols meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed QA/QC instructions are discussed in the NHANES LPM.

Mobile Examination Centers (MECs)

Laboratory team performance is monitored using several techniques. NCHS and contract consultants use a structured competency assessment evaluation during visits to evaluate both the quality of the laboratory work and the quality-control procedures. Each laboratory staff member is observed for equipment operation, specimen collection and preparation; testing procedures and constructive feedback are given to each staff member. Formal retraining sessions are conducted annually to ensure that required skill levels were maintained.

Data Processing and Editing

The data were reviewed. Incomplete data or improbable values were sent to the performing laboratory for confirmation.

Analytic Notes

Refer to the 2015-2016 Laboratory Data Overview for general information on NHANES laboratory data.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted using the appropriate survey design and demographic variables. The NHANES 2015-2016 Demographics File contains demographic data, health indicators, and other related information collected during household interviews as well as the sample design variables. The recommended procedure for variance estimation requires use of stratum and PSU variables (SDMVSTRA and SDMVPSU, respectively) in the demographic data file.

A special one-year MEC sample weight (WTMEC1YR) is provided for the 2015 Surplus Specimen Hepatitis C antibody (confirmed) dataset (SSHC_I_R), and the 2016 Hepatitis C antibody (confirmed) dataset (HEPC_I_R). This sample weight, along with strata (VSTRA) and PSUs (VPSU) are used to calculate variance estimates based on the Taylor Series Linearization method. In addition, 15 Jackknife replicate weights (WTM1YR01 – WTM1YR15) can be used with VSTRA and VPSU, and are included in the files to obtain variance estimates based on a replication method.

This laboratory data file can be linked to the other NHANES data files using the unique survey participant identifier (i.e., SEQN).

Detection Limits

This data is qualitative. The use of lower limits of detection (LLODs) is not applicable.

Exam sample weights should be used for analyses. Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 6 YEARS - 150 YEARS

VPSU - Variance PSU

Variable Name:
VPSU
SAS Label:
Variance PSU
English Text:
Variance PSU
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 15 Range of Values 4133 4133
. Missing 0 4133

VSTRA - Variance stratum

Variable Name:
VSTRA
SAS Label:
Variance stratum
English Text:
Variance stratum
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 1 4133 4133
. Missing 0 4133

WTMEC1YR - Full Sample 1 Year MEC Exam Weight

Variable Name:
WTMEC1YR
SAS Label:
Full Sample 1 Year MEC Exam Weight
English Text:
Full Sample 1 Year MEC Exam Weight
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7275.95925 to 438729.41522 Range of Values 4133 4133
0 No complete MEC collection 0 4133
. Missing 0 4133

WTM1YR01 - 1 Year MEC Weight - Jackknife 01

Variable Name:
WTM1YR01
SAS Label:
1 Year MEC Weight - Jackknife 01
English Text:
1 Year MEC Weight - Jackknife replicate weight 01
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8247.701229 to 440150.40271 Range of Values 3863 3863
0 Not in Replicate Sample 270 4133
. Missing 0 4133

WTM1YR02 - 1 Year MEC Weight - Jackknife 02

Variable Name:
WTM1YR02
SAS Label:
1 Year MEC Weight - Jackknife 02
English Text:
1 Year MEC Weight - Jackknife replicate weight 02
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7480.396762 to 515579.03271 Range of Values 3830 3830
0 Not in Replicate Sample 303 4133
. Missing 0 4133

WTM1YR03 - 1 Year MEC Weight - Jackknife 03

Variable Name:
WTM1YR03
SAS Label:
1 Year MEC Weight - Jackknife 03
English Text:
1 Year MEC Weight - Jackknife replicate weight 03
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
9333.577559 to 443870.47823 Range of Values 3808 3808
0 Not in Replicate Sample 325 4133
. Missing 0 4133

WTM1YR04 - 1 Year MEC Weight - Jackknife 04

Variable Name:
WTM1YR04
SAS Label:
1 Year MEC Weight - Jackknife 04
English Text:
1 Year MEC Weight - Jackknife replicate weight 04
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7778.572341 to 449405.45992 Range of Values 3851 3851
0 Not in Replicate Sample 282 4133
. Missing 0 4133

WTM1YR05 - 1 Year MEC Weight - Jackknife 05

Variable Name:
WTM1YR05
SAS Label:
1 Year MEC Weight - Jackknife 05
English Text:
1 Year MEC Weight - Jackknife replicate weight 05
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7795.706633 to 470951.58808 Range of Values 3859 3859
0 Not in Replicate Sample 274 4133
. Missing 0 4133

WTM1YR06 - 1 Year MEC Weight - Jackknife 06

Variable Name:
WTM1YR06
SAS Label:
1 Year MEC Weight - Jackknife 06
English Text:
1 Year MEC Weight - Jackknife replicate weight 06
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7684.808411 to 456551.09648 Range of Values 3889 3889
0 Not in Replicate Sample 244 4133
. Missing 0 4133

WTM1YR07 - 1 Year MEC Weight - Jackknife 07

Variable Name:
WTM1YR07
SAS Label:
1 Year MEC Weight - Jackknife 07
English Text:
1 Year MEC Weight - Jackknife replicate weight 07
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8271.785033 to 480173.70938 Range of Values 3862 3862
0 Not in Replicate Sample 271 4133
. Missing 0 4133

WTM1YR08 - 1 Year MEC Weight - Jackknife 08

Variable Name:
WTM1YR08
SAS Label:
1 Year MEC Weight - Jackknife 08
English Text:
1 Year MEC Weight - Jackknife replicate weight 08
Target:
Both males and females 20 YEARS - 69 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7563.254009 to 455216.39006 Range of Values 3907 3907
0 Not in Replicate Sample 226 4133
. Missing 0 4133

WTM1YR09 - 1 Year MEC Weight - Jackknife 09

Variable Name:
WTM1YR09
SAS Label:
1 Year MEC Weight - Jackknife 09
English Text:
1 Year MEC Weight - Jackknife replicate weight 09
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7651.242087 to 472153.09801 Range of Values 3868 3868
0 Not in Replicate Sample 265 4133
. Missing 0 4133

WTM1YR10 - 1 Year MEC Weight - Jackknife 10

Variable Name:
WTM1YR10
SAS Label:
1 Year MEC Weight - Jackknife 10
English Text:
1 Year MEC Weight - Jackknife replicate weight 10
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7275.84585 to 497919.89118 Range of Values 3823 3823
0 Not in Replicate Sample 310 4133
. Missing 0 4133

WTM1YR11 - 1 Year MEC Weight - Jackknife 11

Variable Name:
WTM1YR11
SAS Label:
1 Year MEC Weight - Jackknife 11
English Text:
1 Year MEC Weight - Jackknife replicate weight 11
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7378.103483 to 522362.98389 Range of Values 3846 3846
0 Not in Replicate Sample 287 4133
. Missing 0 4133

WTM1YR12 - 1 Year MEC Weight - Jackknife 12

Variable Name:
WTM1YR12
SAS Label:
1 Year MEC Weight - Jackknife 12
English Text:
1 Year MEC Weight - Jackknife replicate weight 12
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7585.373999 to 498117.42312 Range of Values 3870 3870
0 Not in Replicate Sample 263 4133
. Missing 0 4133

WTM1YR13 - 1 Year MEC Weight - Jackknife 13

Variable Name:
WTM1YR13
SAS Label:
1 Year MEC Weight - Jackknife 13
English Text:
1 Year MEC Weight - Jackknife replicate weight 13
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8624.806378 to 452639.16422 Range of Values 3801 3801
0 Not in Replicate Sample 332 4133
. Missing 0 4133

WTM1YR14 - 1 Year MEC Weight - Jackknife 14

Variable Name:
WTM1YR14
SAS Label:
1 Year MEC Weight - Jackknife 14
English Text:
1 Year MEC Weight - Jackknife replicate weight 14
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8027.195571 to 465861.1139 Range of Values 3843 3843
0 Not in Replicate Sample 290 4133
. Missing 0 4133

WTM1YR15 - 1 Year MEC Weight - Jackknife 15

Variable Name:
WTM1YR15
SAS Label:
1 Year MEC Weight - Jackknife 15
English Text:
1 Year MEC Weight - Jackknife replicate weight 15
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7529.52883 to 472359.3067 Range of Values 3942 3942
0 Not in Replicate Sample 191 4133
. Missing 0 4133

LBDHCI - Hepatitis C Antibody (confirmed)

Variable Name:
LBDHCI
SAS Label:
Hepatitis C Antibody (confirmed)
English Text:
Hepatitis C Antibody (confirmed)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Positive 18 18
2 Negative 9 27
3 Negative Screening HCV Antibody 3717 3744
4 Positive HCV RNA 31 3775
. Missing 358 4133