Factors Associated With Prevalent Hepatitis C: Differences Among Young Adult Injection Drug

Users in Lower and Upper Manhattan, New York City

American Journal of Public Health 23

January 2001, VoL91, No.

Theresa Diaz, MD, MPH, Don C. Des Jarlais. PhD, David Vlahov. PhD. Theresa E. Perlis, PhD, Vincent Edwards. Samuel R. Friedman. PhD. Russell Rockwell, PhD, Donald Hoove1; PhD. Ian T Williams. PhD, and Edgar R. Monterroso, MD

Abstract

Objectives:  This study examined correlates of prevalent hepatitis C virus (Hepatitis C Virus) infection among young adult injection drug users in 2 neighborhoods in New York City.

Methods:  Infection drug users aged 18 to 29 years were street recruited from the Lower East Side and Harlem.  Participants were interviewed about drug use and sex practices; venipuncture was performed for hepatitis B virus (HBV), Hepatitis C Virus, and HIV serologies.

Results:  In both sites, testing positive for Hepatitis C Virus antibody (anti-Hepatitis C Virus) was associated with having injected for more than 3 years.  Additionally, Hepatitis C Virus infection was positively associated with injecting with someone known to have had hepatitis (but the association was significant only in the Lower east Side) and with sharing cotton (but the association was statistically significant only in Harlem).  Being in drug treatment and older than 24 years were associated with Hepatitis C Virus in the Lower East Side but not in Harlem.  Receiving money for sex was associated with anti-Hepatitis C Virus positively in Harlem but not in the Lower East Side.

Conclusion:  Several differences in factors associated with prevalent Hepatitis C Virus infection existed among 2 populations of young injection drug users from the same city.  Indirect transmission of Hepatitis C Virus may occur.  (Am J Public Health 2001; 91: 23-30)

Injection drug users are at high risk for hepatitis C virus (Hepatitis C Virus) infection.^1-3 Although geographic variation exists, Hepatitis C Virus rates among injection drug users are often higher than 60% and in many cities approach 90%.^4-7 A recent study in Baltimore, Md, showed that Hepatitis C Virus infection rates were 60% among injection drug users with less than 2 years ' experience with injection.⁸ If transmission is indeed this rapid (and efficient), then more aggressive public health measures are needed to reduce trans- mission in this vulnerable population. Aggressive prevention of Hepatitis C Virus also is important be- cause therapy for Hepatitis C Virus is costly and, so far in the United States, usually not offered to active injection drug users!'3 Unfortunately, some studies suggest that high Hepatitis C Virus infection incidence among injection drug users is the result of the already high proportion with chronic infection (approaching 85% of those infected), providing a huge reservoir from which trans- mission can occur.² High Hepatitis C Virus prevalence among young injectors from different locations adds additional urgency to the call for more in- tense and sustained preventive measures.

The purpose of this study was to examine rates and correlates of Hepatitis C Virus infection among young adult (mostly recent onset) injection drug users in 2 very different neighborhoods in New York City: the Lower East Side and Harlem. We examined factors associated with prevalent Hepatitis C Virus infection from baseline inter- views conducted from 1997 through 1998 among injection drug users aged 18 to 29 years in these 2 neighborhoods.

Methods

Study Population

The study population was recruited (during 1997-1998) as part of a cohort study from 2 of 6 Centers for Disease Control and Prevention sites for the Collaborative Injection Drug User Study II. The 2 New York City sites were located in the Lower East Side (conducted by Beth Israel Medical Center and National Development and Research Institutes) and in Central and East Harlem (conducted by Center for Urban Epidemiologic Studies, New York Academy of Medicine ). Eligibility criteria and the core questionnaire were the same for all sites; recruitment methods may have varied slightly by sites, but for all sites, street recruitment (not recruitment from drug treatment programs) was the focus.

Eligibility

To be eligible for the study, participants needed for more of the following criteria: to report injection drug use during the previous 6 months, to have injected for less than 3 years, or to be between 18 and 29 years of age. Potential participants were asked a series of questions unrelated to the eligibility criteria (e.g., "Do you have siblings?"). The eligibility criteria were not advertised because we thought that knowledge of these criteria might lead persons to falsely represent their injection practices and age in order to enter the study. Because few injection drug users older than 29 had injected for less than 3 years, for this analysis we included only persons between 18 and 29 years of age.

Sites

The Harlem study, known as Harlem Out-reach Prevention and Education, was conducted from a building in Central Harlem, New York City. Recruitment took place in both Central Harlem (predominantly African American) and East Harlem (predominantly Latino).

For the Lower East Side, the study was conducted in a research storefront office located in that neighborhood. The research store- front has been in continuous operation since 1989 and is well known among drug users in the community. The Lower East Side is an ethnically diverse neighborhood with a large transient population of young White persons from nearby suburbs and the rest of the United States.

Recruitment

Community-based outreach techniques were used to recruit young adult injection drug users. First, ethnographic techniques were used to map Central and East Harlem and the Lower East Side to determine specific areas where young injection drug users congregated. Recruiters were then sent to these areas, where they approached young persons, engaged them in conversation, formally assessed eligibility by asking structured questions, and asked persons who were eligible to participate in the study. Those who agreed to participate in the study were escorted to the study office to receive information about the study and provide informed consent. They also were given a small monetary incentive ($25) after completion of an interview

Data Collection

At baseline, eligible and consenting participants unde1Went standardized face-to-face interviews conducted by trained interviewers in private rooms as well as venipuncture. Participants received pretest counseling about the serologic tests (Hrv; hepatitis E virus (HEY], and Hepatitis C Virus). Participants were given risk reduction counseling and referral information for services such as drug treatment and social services. To minimize bias, however, this was not done until after the interview was completed.

All participants were offered test results and posttest counseling. Participants with any positive test results were offered referrals for follow-up medical evaluation. Those with negative HBV test results were offered referral for hepatitis B vaccination. The study received institutional review board approval from Beth Israel Medical Center, the National Development and Research Institutes, the New York City Department of Health, and the Centers for Disease Control and Prevention.

Interviews

The interview included questions on sociodemographics, injecting behaviors, sexual behaviors, and quasi networks. Drug use questions included age at which the participant first injected drugs and the age of the person(s) who initiated the participant into injection drug use. Other drug use questions focused on the 6 months prior to the interview and included frequency of injecting, type(s) of drug injected, use of direct sharing (using a syringe after someone else) and indirect sharing (using cot- ton, rinse water, or a cooker after someone else), and use of syringe exchange or drug treatment. Sex practice variables, including number of sex partners, sexual preference, exchange of sex for money or drugs, and use of condoms (separately for steady and non-steady partners), were ascertained for 6 months preceding the interview. Finally, persons were asked whether they had ever been raped, been in prison, or injected with someone known to have had hepatitis (quasi network).

Laboratory Analysis

Serum from blood specimens was analyzed for HIV-I antibodies by standard techniques at local laboratories. Specimens repeatedly reactive on enzyme-linked immunosorbent assay were confirmed with Western blot.

Blood specimens were sent to the Centers for Disease Control and Prevention to test serologic markers for HBV arid Hepatitis C Virus infection. Samples were tested for antibody to Hepatitis C Virus (Abbott Hepatitis C Virus EIA 2.0, Abbott Laboratories, Chicago, Ill). A sample of 100 specimens repeatedly reactive for Hepatitis C Virus based on enzyme immunoassay received supplemental testing, and results for all were found to be positive. Because of the high positive predictive value of repeat reactive enzyme immunoassay testing in this population, no further supplemental Hepatitis C Virus testing was performed. Therefore, persons with positive repeat reactive enzyme immunoassay test results were considered to have evidence of past Hepatitis C Virus infection.

Samples were tested for antibody to HBV core antigen (anti-HBc) (CORAB, Abbon Laboratories, Chicago, III). Samples testing positive for anti-HBc were then tested for hepatitis B surface antigen (HBsAg) (AUSAB EIA, Abbon Laboratories), and if the results were negative, the samples were tested for antibody to HBsAg (anti-HBs) (AUSTRIA II-125,Ab- bon Laboratories). Because of this sequence of testing, many serum samples of blood did not contain sufficient amounts for the anti-HBs testing. Therefore, in the analysis, only data on anti-HBc and HBsAg are presented. Persons with positive test results for either anti-HBC alone or for anti-HBc in combination with HBsAg were considered to have evidence of HBV infection.

Statistical Analysis

Initial frequency comparisons were made between the 2 sites to examine the proportion of subjects by sociodemographic characteristics; initiation of injection drug use; gender; whether participants had ever been raped or been in prison; quasi network; HC~ HB~ and HN status; and drug use behaviors and sexual behaviors in the past 6 months.

The prevalence of Hepatitis C Virus infection by num- her of years of injection drug use was calculated separately for each site, and Mantel-Haenszel X2 tests for linear trend were used to determine whether Hepatitis C Virus infection was associated with the number of years of injection drug use.

Within each site, contingency tables with prevalence odds ratios (ORs) and 95% confidence intervals (CIs) were used to study un- adjusted associations between different risk factors and Hepatitis C Virus infection. Because of the great differences between Harlem and the Lower East Side, these associations were examined separately for each site.

To study adjusted associations between risk factors and Hepatitis C Virus infection, we developed multivariate logistic regression models separately for each site in the following manner. All factors found in the univariate analysis for the given site to have prevalence odds ratios that (with 95% confidence intervals) excluded unity were entered into each model. HBV infection was not considered because it is an out- come of the same risky behavior that leads to Hepatitis C Virus infection.

Backward stepwise elimination was done with SAS (SAS Institute Inc, Cary, NC) de- fault criteria for removal from the model. For each site-specific analysis, the remaining variables were examined for collinearity (i.e., Pearson correlation coefficient>O.5) within each site. The following pairs of variables were found to be collinear within both sites: (1) use

TABLE 1-Baseline Sociodemographics, Lifetime Events, Network, Behaviors, and Serologic Test Results of Young Injection Drug Users in New York City, by Site of Recruitment