Overall, 35 participants tested anti-HCV-positive, for a weighted prevalence of 2.2% (95% CI 1.5% to 3.3%). Multiplying this by 80% to adjust for the fact that some antibody-positive individuals are no longer infected gives a chronic HCV infection prevalence estimated at 1.8%.
Anti-HCV prevalence was strongly associated with age (p
0.001 for linear trend), with the highest rate among those aged 50–59 years (5.8%, 95% CI 3.3% to 10.0%), corresponding to dates of birth from 1945 to 1954. Among 476 study participants age 20 to 29 years, none were anti-HCV-positive (Table ). Anti-HCV prevalence was higher among US-born than foreign-born participants (3.1% vs. 1.3%, p
0.04), and higher among those with a lifetime history of incarceration as an adult than those never incarcerated (8.4% vs. 1.5%, p
0.02). Prevalence was higher among those with less education (p
0.04) and those receiving public assistance (p
0.03). Differences by race and ethnicity were not statistically significant.
Anti-HCV prevalence in NYC by selected demographic, health, and behavioral characteristics
The largest differences in prevalence were associated with well-established risk factors for acquiring HCV. Among the 35 anti-HCV-positive participants, 13 reported a history of injection drug use and five reported a blood transfusion prior to 1992 (two of these reported both injection drug use and transfusion). Among participants with a lifetime history of injection drug use, anti-HCV prevalence was 64.5%, compared to 1.1% among those with no history of drug use (p
0.001). Of the 13 anti-HCV-positive participants with a history of injection drug use, ten reported no current drug use, two reported current drug use, and one did not respond. Anti-HCV prevalence was 11.9% among those with a history of blood transfusion prior to 1992, compared to 1.8% among those without (p
Telephone follow-up interviews were attempted with 34 of the 35 anti-HCV-positive participants (one had requested in advance that survey staff not contact him). Sixteen were unreachable (four disconnected telephones, two apparent wrong telephone numbers, two participants with unknown telephone numbers, and the remainder did not respond to telephone messages or letters). Of 18 reached by phone, 13 reported that they had been aware of their HCV status prior to the survey, and five learned about their HCV status as a result of the survey. Of note, four of these five had no obvious risk factors for infection.
Anti-HCV prevalence in NYC HANES was compared to that in the national NHANES (Table ). After age adjustment, the overall anti-HCV prevalence was 2.3% in NYC (95% CI 1.5–3.5%) and 1.8% in NHANES (95% CI 1.3–2.6%); the observed difference was not statistically significant. For each of the subgroups examined, by gender, age, or race/ethnicity, the prevalence in NYC was somewhat higher than nationally, again without statistical significance. The same patterns were seen in NYC as nationally, i.e., higher prevalence for men, Blacks, and people in their 50s. NYC HANES data allowed an estimation of prevalence for Asians (2.4%, 95% CI 0.6–9.2), whereas in the national data an estimate for Asians was not available because of small sample size. Hispanic populations are presented differently in NYC and nationally, so direct comparisons are not possible. In NHANES, most Hispanic participants are Mexican-American and are presented separately as such. Most Hispanics in NYC, however, have ancestors from the Caribbean, and for NYC HANES, all Hispanics are presented together, with an anti-HCV prevalence of 1.4% (95% CI 0.6–3.4).
Comparison of age-adjusted anti-HCV prevalence between NYC HANES and national HANES