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High prevalence of HCV in a cohort of injectors on methadone substitution treatment

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Abstract

Background

In Hong Kong, methadone treatment is widely accessible. Injecting drug users (IDU) have a relatively low risk behavioural profile and low HIV prevalence (0.3%). The corresponding Hepatitis C (HCV) level, however, is unclear.

Objectives

To determine the HCV prevalence in IDU in Hong Kong and to identify any associated factors.

Study Design

A community-based HCV prevalence study of IDU was conducted in methadone clinics. Demographics and drug use pattern were collected through a questionnaire survey and blood samples were obtained for HCV serological tests.

Results

Data of 567 IDU were analyzed. Most were male (84%) and ethnic Chinese (98%). The median age was 49 years and median injection duration 17 years. Two-thirds (62%) admitted ever sharing injecting equipments. Most (76%) reported having injection drug use in the preceding 3 months, and 44% abused midazolam/triazolam in addition to heroin. Prevalence of HCV antibodies was 85% (95% confidence interval 82.5–88.3%). Injection duration, recent injection, ever sharing injecting equipments and concomitant use of other drugs were independent factors associated with HCV infection.

Conclusions

HCV prevalence is high in IDU despite a low HIV prevalence and widely available substitution treatment, which has probably slowed but not prevented the HCV epidemic in IDU in Hong Kong.

Introduction

Hong Kong has a long established methadone treatment programme with over 90% coverage (Hong Kong Advisory Council on AIDS, 2006). By reducing risk behaviours, the programme is considered to have contributed significantly to the low HIV level in drug users. The HIV prevalence among drug users in Hong Kong, 0.3% in 2006 (Department of Health, 2007), is only a tenth of that in neighbouring cities or a hundredth of that in Guangxi province, China (Liu et al., 2006).

Hepatitis C (HCV) and HIV transmit similarly through the transfer of infected blood. It would be interesting to know the HCV epidemiology in drug users in Hong Kong among whom the HIV level is low. Statistics from testing laboratory left-over samples indicated a HCV prevalence of 75% (n = 99, late 80s) and 46% (n = 210, year 2000), but these results are difficult to interpret because of the small sample sizes and lack of subject characteristics such as injection history. The present study has therefore been conceptualized to establish HCV prevalence among injecting drug users (IDU) in Hong Kong and to identify any associated demographic or behavioural risk factors.

Section snippets

Methods

A community-based HCV prevalence study comprising of a behavioural risk questionnaire survey and a seroprevalence study of IDU was conducted. Methadone clinics (MCs) that were attended by at least 200 drug users per day or 40 per hour served as sites for subject recruitment. A series of 4-h sessions were scheduled over a month's time, aiming to recruit 500 IDU with the assistance of four trained peer workers. Inclusion criteria were (a) ever injected illicit drug, (b) agreed to be interviewed

Characteristics of respondents

Twenty-three sessions were held between 20 February and 27 March 2006 in 12 MCs. Excluding 11 duplicated entries and 9 inadequate blood samples, 567 IDU were included in the analysis. A majority were male (n = 477, 84%) and Chinese (n = 546, 98%) with a median age of 49. About one quarter (n = 132, 23%) were not born locally, of whom most (n = 125, 94%) had resided in Hong Kong for at least 5 years.

Drug abuse pattern

Subjects had long injection history (median 17 years). Almost all were currently on methadone treatment (n

Discussion

The HCV prevalence in IDU in Hong Kong is high at 85%. Irrespective of local HIV prevalence, the HCV level is similar to reports elsewhere: 72–95% in Guangxi, China (Garten et al., 2004, Garten et al., 2005), 75% in Australia (Bradshaw et al., 2005), 80% in Europe (Touzet et al., 2000) and 90% in Northern Thailand (Apichartpiyakul et al., 1999). A similar large discrepancy between HIV and HCV prevalence has been reported in Australia (Crofts et al., 1999) and Philippines (Agdamag et al., 2005).

Acknowledgements

The project team is supported by the Research Fund for the Control of Infectious Diseases (RFCID) from the Health, Welfare and Food Bureau of the Hong Kong Special Administrative Region Government. The authors would like to thank staff and peer workers of Society for the Aid and Rehabilitation of Drug Abusers for advice and support, Narcotics and Drug Administration Unit, staff of Auxiliary Medical Staff and Special Preventive Programme of Department of Health for administrative support and

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