Published Online: August 05, 2011
Douglas W. Roblin, PhD; Bryce D. Smith, PhD; Cindy M. Weinbaum, MD, MPH; and Miriam E. Sabin, PhD
Background/Objective: The Centers for Disease Control and Prevention recommends routine screening for the hepatitis C virus antibody (anti- HCV) among persons most likely to be infected. Little is known about anti-HCV screening and prevalence in routine practice settings. We studied anti-HCV screening rates, anti-HCV positivity, and demographic and risk factors associated with increased likelihood of anti-HCV screening or positivity in a managed care organization (MCO).
Methods: This was a retrospective observational study of 17-to-74-year-old MCO enrollees from 2000 to 2007 (N = 557,056; 1,949,499 enrollee years). The primary outcome measures were likelihood of anti-HCV screening and HCV positivity (both in the total population and among those screened). Independent variables were: birth cohort, gender, HCV risk factors, and socioeconomic status (SES) and race of residents’ neighborhoods. Likelihood of each outcome as a function of the independent variables was estimated using logistic regression.
Results: Over the 8-year period, 4.31% of the total population received anti-HCV screening; 0.22% had a positive HCV result. Among those screened, HCV positivity was 5.15%. HCV screening and positivity rates increased over time. Both likelihood of HCV screening and HCV positivity were highest (P <.05) among persons born during 1945-1964, males, those with HCV risk factors, and residents of neighborhoods of lower SES or with higher percentages of African Americans.
Conclusions: Although HCV screening and detection improved in this MCO over an 8-year period, anti-HCV screening was lower than expected. Many persons at risk for HCV remained unscreened. Strategies for improving anti-HCV screening in routine practice are recommended for patients at increased risk.
(Am J Manag Care. 2011;17(8):548-555)
A study was performed of HCV screening and prevalence estimates in a managed care organization, unadjusted and adjusted for HCV risk factors.
This study updates one of the few practice-based assessments of HCV prevalence and positivity previously published in AJMC.
Study results indicate that HCV screening is more likely among adults with HCV risk factors, but that screening rates remain sub-optimal.
Efforts to improve rates and timeliness of anti-HCV screening generally and in specific high prevalence subgroups could identify currently undiagnosed HCV-infected patients, lead to initiation of HCV pharmacotherapy, and reduce future rates of end-stage liver disease.
According to an Institute of Medicine report released in 2010, hepatitis C virus (HCV) infection is a serious public health concern.1 In liver transplant centers in the United States, HCV infection has been found to be the most frequent risk factor for liver cancer.2 Incidence rates of hepatocellular carcinoma in the United States have tripled from 1975 to 2005,3 and have increased at an average annual rate of 3.5% from 2001 to 2006.4 Five-year survival rates for liver cancer are less than 15%,3 and more than 35,000 incident deaths are forecast to be attributable to HCV by 2030 given the aging of the population with chronic HCV infection.5
A study of HCV infection prevalence in the United States using the 1999-2002 National Health and Nutrition Examination Survey (NHANES) estimated that 1.6% of the non-institutionalized non-homeless US population had measurable antibody to HCV (anti-HCV).6 HCV prevalence was significantly higher among specific demographic groups (persons born 1945-1964 [“high prevalence birth cohort”]), males, individuals with specific behavioral risk factors (injection drug use [IDU]), medical and behavioral characteristics associated with HCV infection (elevated serum alanine aminotransferase [ALT] levels, HIV (human immunodeficiency virus) infection, blood transfusion before 1992, higher numbers of lifetime sexual partners), and those with selected socioeconomic characteristics (high school education or less, income below the poverty threshold). Screening among a random sample of Veterans Administration (VA) medical center users indicated that HCV positive rates were approximately 5.4%.7
Since 1998, the Centers for Disease Control and Prevention (CDC) has recommended that screening for anti-HCV should be routinely offered to persons most likely to be infected with HCV.8 Yet, little is known about anti-HCV screening practices and HCV infection prevalence in routine practice settings. Analysis of UnitedHealthcare medical claims from 1997 to 1999 indicated that 0.7% of enrollees were ever screened for HCV and, of those, 6.7% were HCV-positive (approximately 0.08% of the enrollee population).9 This HCV infection prevalence was much lower than that detected in the NHANES and VA studies and suggests that current anti-HCV screening practice may fail to detect many infected persons who could benefit from primary and secondary prevention counseling and medical management.
Both provider and patient factors might influence anti-HCV screening in routine practice. Physicians frequently do not collect HCV risk factor information from new patients; and, even if a patient has a risk factor, providers often do not order anti-HCV screening tests.10-13 Patients may not admit to stigmatizing behaviors, such as IDU, that might prompt providers to screen.14,15 Consequently, the majority of HCV-infected adults are most likely unaware of their infection and therefore do not seek out appropriate treatment or prevention services.16-19
To assess how CDC recommendations for anti-HCV screening are currently implemented in a typical healthcare setting, we conducted a retrospective observational study of HCV screening and HCV infection prevalence among adult enrollees of a managed care organization (MCO) from 2000 through 2007. Our study had 2 objectives: to estimate 1) cumulative rates of anti-HCV screening and positivity in this MCO, and 2) association of enrollee demographic and risk factors with likelihood of anti-HCV screening and positivity.
Kaiser Permanente Georgia (KPG) is a federally qualified, group- and network-model MCO that, during the study period, provided comprehensive medical services to approximately 275,000 members per year in the metropolitan Atlanta area. This study protocol was reviewed and approved by the KPG Institutional Review Boards (IRBs) and CDC.
Practice Guidelines for HCV Screening
KPG’s clinical practice guidelines recommend enzyme immunoassay (EIA) for anti-HCV screening, with confirmation by reverse transcriptase–polymerase chain reaction if the initial screening test is reactive. These guidelines recommend anti-HCV testing according to “risk for infection” including: IDU history or other illegal drug use, history of chronic hemodialysis, persistently abnormal ALT levels, receipt of clotting factor concentrate before 1987, and receipt of blood transfusion or organ transplant before July 1992.
KPG computerized databases were the source of data for enrollee demographics, enrollment history, laboratory screens and results, and diagnoses and procedures (both International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]-coded and Current Procedural Terminology, 4th Edition [CPT-4]-coded) associated with ambulatory, emergent, and hospital care. All records can be linked at the individual level using unique identifiers. Residential addresses of KPG enrollees are geocoded to US Census tracts and block groups using MapMaker Plus (Mapinfo, Troy, New York) for linking to Summary File 3 (SF3) records.
The study population consisted of 557,056 enrollees, aged 17 to 74 years, impaneled to a KPG primary care physician, and enrolled at least 1 month during 2000-2007. The population was constructed year by year, with age defined as of January 1st of each year. Thus, an enrollee who was 17 to 74 years of age as of January 1st of a year and enrolled for at least 1 month during that year would be included for that year. An enrollee <17 years or >74 years as of January 1st of a year or an enrollee without enrollment in a year would not be included for that year. Thus, the final analysis data set included 1,949,499 enrollee-years.
HCV Screening. HCV screening was defined as having had an HCV antibody laboratory assay performed, either an anti-HCV EIA or recombinant immunoblot assay (RIBA). HCV RNA assays, for quantitative measurement of viral load, were not considered to be screening tests in this study.
Annual and cumulative anti-HCV screening rates were defined. For tracking annual rates of HCV screening, each age-eligible enrollee with enrollment in a study year was ascertained for receipt of at least 1 anti-HCV screening test in that year. History of anti-HCV screening for each enrollee was then assessed across the 8-year period to determine if the enrollee was “ever screened.”
HCV Positivity. HCV positivity was defined as an indication in the laboratory records of a positive result on an anti-HCV screening test. Annual and cumulative anti-HCV positivity rates were defined similar to HCV screening.
Neighborhood Socioeconomic Status Index. A neighborhood socioeconomic status (SES) index is defined from principal components analysis of 7 of the 2000 SF3 variables for each enrollee’s geocoded Census tract or block group (518,639 of the 557,056 enrollees in the study population): 1) Percent of households with income below the poverty level, 2) Percent of households receiving public assistance, 3) Percent of households with annual income below $30,000, 4) Percent of working age adult males not in the labor force, 5) Percent of adults 25 years and older with a high school education or less, 6) Log of median household income, and 7) Log of median value of single family homes. The selected variables are based on previous studies.20,21 Factor scores obtained from the principal components analysis are used to assign enrollees to quartiles of an SES index.
Percent African American Residents in Neighborhood. Percent of African American residents in a neighborhood was also obtained from the 2000 SF3 data set for each enrollee’s geocoded Census tract or block group. This variable serves as a proxy measure for race since individual-level race is not generally available. Internal KPG studies show a significant positive correlation at the Census tract level between self-report from surveys and this SF3 measure (Pearson coefficients >0.80).
Covariates. In addition to these 2 area-based measures, individual-level covariates were defined for duration of enrollment during 2000-2007 (<1, 1-2, 3-4, and >4 years), selected HCV risk factors, and birth cohort. Given the potential confusion caused by differences in terminology regarding behavioral risk factors, medical risk markers, and healthcare and environmental exposures, we consolidate these categories under the single term risk factors for the sake of brevity in the narrative. HCV risk factors were defined for IDU, coagulation defects (eg, hemophilia), dialysis, HIV, and elevated ALTs (eAppendix, available at www.ajmc.com). These measures were selected because they were 1) listed as indications for HCV screening in KPG’s clinical practice guidelines or referenced in the provider focus groups and 2) could be measured using KPG computerized data beginning with 1995 (the first year for which reliable and complete computerized data were available). Other HCV risk factors (eg, blood transfusions prior to 1992) were not measured due to incomplete data prior to 1995. Birth cohorts were defined by year of birth and classified into 5-year subgroups.
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