1 Greater Glasgow Health Board, Glasgow, United Kingdom.
2 School of Nursing, Midwifery and Health, University of Paisley, Paisley, United Kingdom.
3 Scottish Centre for Infection and Environmental Health, Glasgow, United Kingdom.
4 Public Health and Health Policy Section, University of Glasgow, Glasgow, United Kingdom.
5 Regional Virus Laboratory, North Glasgow Hospitals University Trust, Glasgow, United Kingdom.
6 Scottish Prisons Service, Edinburgh, United Kingdom.
Received for publication January 22, 2003; accepted for publication September 9, 2003.
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ABSTRACT |
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hepacivirus; hepatitis C; incidence; prisoners; prisons; risk-taking; substance abuse, intravenous
Abbreviations: Abbreviations: CI, confidence interval; HCV, hepatitis C virus; HMP, Her Majestys Prison.
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INTRODUCTION |
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In Western countries, HCV is most commonly transmitted among injecting drug users who share injecting equipment (2). It is well recognized that the prevalence of HCV among prison inmates, especially those who inject drugs, is high (3) and that most drug injectors eventually become incarcerated (4). Five cases of HCV infection occurring during incarceration have been reported in Australia (5, 6), and a few cohort studies (712) have examined the incidence of HCV among prison inmates, though not all could categorically exclude transmission occurring during the period just prior to prison entry; all but one involved the use of attributable HCV testing. This report presents the findings of a cohort study conducted, using a novel recruitment and testing approach, to gauge the incidence of HCV infection and associated risk factors among inmates during their imprisonment.
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MATERIALS AND METHODS |
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To ensure that any HCV antibody seroconversions observed were the result of transmission in prison, we required inmates to have been incarcerated for at least 6 months before providing their first sample; it is estimated that 97 percent of persons seroconvert within 6 months of acquiring HCV (11). Only those inmates who did not leave prison, for any reason, during their sentence were eligible for inclusion. Ethical permission was granted by the local Health Board Ethics Committee. Inmates were told that separate, additional arrangements would be made if they wanted a named HCV test.
Setting
The study was undertaken at Her Majestys Prison (HMP) Shotts in central Lanarkshire, Scotland, a large (460 inmates), maximum-security, long-stay (all sentences exceeding 4 years) male prison serving all of Scotland.
Recruitment
The participants were recruited between April 1999 and October 2000. The first of five cohorts was accessed from all existing inmates as of April 1999. Cohorts 25 comprised new entrants to the prison, and these inmates were enlisted at 3-month intervals. Participation was voluntary and anonymous, thus allowing inmates who would not have participated if they had had to undergo named testing to participate; consent was verbal.
Prior to the first day of data and saliva collection for each cohort, the principal researcher held study briefings and question/answer sessions attended by over 70 percent of eligible inmates and by prison staff. A team of assistants, independent of the prison service, was trained to help with recruitment, the collection and labeling of saliva samples, and administration of the questionnaire. Fifteen inmate "volunteer overseers" were recruited to ensure that the agreed-upon study procedure was adhered to, to publicize the study, and to encourage fellow inmates to attend talks and participate. The prison officers were not directly involved in the study, and at all times the research teams independence from the Scottish Prison Service was emphasized.
Questionnaire
The first questionnaire inquired about demographic factors and risk behaviors engaged in before and during the inmates current sentence. The follow-up questionnaire asked about behaviors in the previous 6 months. The questionnaire was pilot-tested on 40 inmates in HMP Edinburgh.
HCV antibody testing
We chose saliva as the body fluid for HCV antibody testing (3) to avoid venipuncture. Samples were tested at the West of Scotland Regional Virus Laboratory using an assay that has 85 percent sensitivity and 100 percent specificity (13).
Procedure for collecting and linking samples
On data collection days, the assistants and volunteer overseers distributed the questionnaires to the participants, who completed them in the privacy of their own cells. Inmates were then escorted to a recreation hall, where they provided a saliva sample by chewing on a swab that was then returned to its container.
We adopted the following design to link two sets of saliva samples and questionnaires that were anonymous. On the first data collection day, the participant was asked to choose an envelope that contained two smaller envelopesone marked "open first visit" and the other marked "open second visit." Inside each of these smaller envelopes was a pair of numbered stickers. The numbers on all four stickers were identical, but those in the first envelope were printed in red and those in the second were printed in black. The participant attached one red sticker to his saliva sample container and one to his questionnaire. He then wrote his prisoner number across the edge of the sealing flap of the large envelope, with the "open second visit" envelope still inside, and resealed it. Transparent cellophane tape was then placed over the written number, thus ensuring that it could not be altered. The envelope was kept in a safe until the second study day, when the participant repeated the above process with the black stickers. Thus, corresponding saliva samples and questionnaires for both occasions could be linked via the numbered labels. The study components were then rendered anonymous by destroying, in his presence, the participants study envelope on which was written his prisoner number.
Statistical analysis
Analysis was confined to inmates who were negative for HCV antibody in their saliva at recruitment and who had a 6-month follow-up HCV saliva test result. Data were analyzed using Stata software (14). The incidence of HCV infection was calculated using the person-years method (15), where the date of seroconversion was taken as the midpoint of the follow-up period. Confidence intervals for incidences were calculated using an exponential error factor (16). Binomial regression was used to assess risk factors for HCV seroconversion.
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RESULTS |
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HCV antibody prevalence
Of the saliva samples taken from the 612 inmates recruited, 17 were insufficient for HCV antibody testing and four generated inconsistent results. Of the remaining 591 inmates, 93 (16 percent; 95 percent confidence interval (CI): 13, 19) had HCV antibodies in their saliva.
Six-month follow-up and participation
Of the 612 inmates recruited, 171 (28 percent) were ineligible to participate in the 6-month follow-up interview for reasons of liberation, transfer to another prison or a court, or a hospital visit. Eighty-five percent (375/441) of the eligible inmates participated in the second stage of data collection; consistent questionnaire information and sufficient saliva samples, generated on the first study day, were available for 362 of the 375 inmates.
Characteristics of the follow-up group
The characteristics of the follow-up group (n = 362) were compared with those of inmates who similarly provided consistent questionnaire information and sufficient saliva samples on the first day of the study but were not followed up because of either nonparticipation or ineligibility (n = 229 (i.e., 591 362)). The former group had shorter sentences (83 percent and 74 percent of those followed up and those not followed up, respectively, were incarcerated in 1995 or later; p = 0.009) and were younger (24 percent and 35 percent of those followed up and not followed up, respectively, were over age 35 years; p = 0.01); however, no other significant demographic or behavioral differencesparticularly injection-related differences (32 percent and 26 percent of those followed up and not followed up, respectively, were ever injectors; p = 0.1)between the two groups were evident.
HCV antibody incidence
Of the 362 inmates followed up, 53 had a first saliva specimen that was positive for antibodies to HCV; all corresponding second specimens tested positive. Of the remaining 309 inmates, two of the second saliva specimens were insufficient. Five of the 307 inmates who were initially negative for antibodies to HCV seroconverted to positive. Thus, the cumulative exposure time for all 307 inmates was 152.25 years ([(307 5) x 0.5 years] + [5 x 0.25 years]). Hence, the incidence was 3.3 per 100 person-years of incarceration risk (5 x 100/152.25) (table 1).
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For participants who reported having shared needles/syringes during follow-up (3 percent), having injected drugs during follow-up (4 percent), having ever injected drugs (24 percent), and having never injected drugs (76 percent), the respective incidences per 100 person-years of incarceration risk were 26.7 (95 percent CI: 3.8, 100), 19.1 (95 percent CI: 2.7, 100), 11.9 (95 percent CI: 4.5, 31.8), and 0.9 (95 percent CI: 0.1, 6.3) (table 1). In univariate analyses, inmates who reported having ever injected drugs (relative risk = 13.0, 95 percent CI: 1.5, 114.3) and having shared needles/syringes during follow-up (relative risk = 9.0, 95 percent CI: 1.1, 71.7) were at significantly increased risk of incident HCV infection compared with those who had never injected and never shared, respectively. Upon adjustment for other factors, ever having injected drugs was the only independent significant risk factor.
Other risk behaviors that applied to the 6-month period of follow-upbeing involved in a bloody fight (reported by 14 percent), being stabbed with a needle (1 percent), having ones body pierced (1 percent), being tattooed (2 percent), and engaging in anal sex (1 percent)were not associated with HCV seroconversion.
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DISCUSSION |
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The potential to identify the exact means through which the five inmates became infected was limited by our study design, which depended on self-reporting of risk behaviors. The use of self-completed questionnaires should have minimized socially desirable responding (18); the validity of self-reported drug use outside, though not within, the prison setting has been demonstrated to be satisfactory (19, 20). Nevertheless, risk behavior data should be interpreted with caution. Four of the five seroconverters had ever injected drugs; only one admitted to injecting during his current sentence. Since those who had ever injected drugs, but not during the current sentence, had no additional significant risk factors (tattooing, body piercing, bloody fights, anal sex) over their noninjector counterparts, injecting in prison seems the most likely explanation for infection occurring in at least four of the five cases.
A community study of drug injectors conducted in nearby Glasgow during 1999 (A. Taylor, University of Paisley, personal communication, 2000) confirmed that the great majority of HCV-infected drug injectors acquire their infection outside of prison (21, 22). What this study has demonstrated, however, is that HCV can be transmitted within a prison, most likely as a consequence of injecting drug use. Following an outbreak of human immunodeficiency virus infection at HMP Glenochil in 1993 (23), the Scottish Prison Service introduced several measures to prevent the transmission of bloodborne infections inside prison; these included the provision of bleach tablets for sterilizing injection equipment and drug counseling, detoxification, and drug behavior management programs. These interventions were unable to prevent the infections detected at HMP Shotts, though it is possible that more would have occurred if, for example, bleach tablets had not been available (24).
In late 2000, following the conclusion of the study, methadone maintenance programs began to be introduced in Scottish prisons, as advocated in the Scottish Prison Service strategy "Action on Drugs," published that year (25). While this intervention has not been well evaluated in the prison environment, it is hoped that its effectiveness in reducing injectors need to inject drugs outside the prison (26) will be replicated inside. Indeed, one of the seroconversions in our study might have been prevented if such programs had been implemented earlier.
Another method of bloodborne virus prevention among drug injectorsneedle/syringe exchangehas not yet been shown to prevent HCV in the community (27). Although a few prisons worldwide provide inmates with sterile needles and syringes (28), the concept is anathema to most prison officers and is unlikely to be adopted in this setting in the United Kingdom.
It is clear that drug injection equipment is shared inside prisons. The most effective way to prevent HCV transmission in prisons is to avoid, where possible, the incarceration of drug injectors. Drug courts, which offer injectors who have offended because of their drug use a treatment regimen as an alternative to imprisonment, are functioning in parts of some countries, including the United States and the United Kingdom. With prison populations in Scotland and throughout the rest of Europe continuing to increase in size (28, 29) and with these populations harboring reservoirs of HCVas the prevalence of HCV infection (16 percent) at HMP Shotts indicatesthe enormity of the challenge of curbing injecting drug use in prisons is evident.
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ACKNOWLEDGMENTS |
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NOTES |
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REFERENCES |
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