Why we carried out the study

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The prevalence of antibodies to hepatitis B core antigen, hepatitis C virus, and HIV in prison inmates is high.¹ The burden of these infections among those entering the Irish prison system was unknown.

	What were the main findings?

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The overall prevalence of antibodies to hepatitis B core antigen was 6%, to hepatitis C virus 22%, and to HIV 2%. A third of prison entrants (197/591) had never previously been in prison. Only 7% (14/197) of those entering prison for the first time had ever injected drugs, compared with 40% (157/394) of those previously imprisoned (P<0.0001). Bloodborne infections were more common among drug injectors who had previously been in prison than among injectors who had not previously been in prison.

	How did we perform the study?

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We used similar methods to those we used in the recent national census survey.¹ There are about 11 000 committals to seven prisons each year in the Republic of Ireland. We excluded two of these committal prisons from the survey because the numbers committed in preceding years were small (5% of annual committals). Between 6 April and 1 May 1999 we visited each of the five prisons daily and interviewed all those committed within the previous 48 hours. The survey was anonymous and comprised a questionnaire, derived from questionnaires used in other prison surveys,^1-7 and collection of an oral fluid sample.¹

Our study received ethical approval from the Federated Dublin Voluntary Hospitals Joint Research Ethics Committee.

	What were the detailed results?

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Details of participants and prevalence of viral antibodies
During the survey period 607 of the 627 available entrants to the five survey prisons took part (97%). Our analyses refer to the 596 participants who provided analysable oral fluid samples or, for use of injected drugs, the 593 respondents who also declared their injector status. Denominators vary because not all respondents answered all questions.

Injecting drug use, tattoos, treatment for sexually transmitted diseases, and hepatitis B vaccination
Over 70% (120/167) of injecting drug users stated that they had injected drugs in the month before the survey; 85 reported injecting more than 20 times. Of the 156 injectors previously in prison, over half (85/156) reported sharing needles while incarcerated; almost a fifth (29/156) reported starting their injecting habit in prison.

Clarifying the association between risk behaviours and presence of viral antibodies
We developed multiple logistic regression models to clarify the associations between prisoners' characteristics and reported risk behaviours and their likelihood of testing positive for the three viral antibodies (table 2). The most important predictor of hepatitis antibodies was a history of injecting drugs. The likelihood of testing positive for hepatitis C antibodies increased with increasing time spent in prison in the preceding 10 years. Although inferences from the HIV regression model are limited by small numbers, those who had spent more than three of the preceding 10 years in prison were significantly more likely to test positive for HIV antibodies.

	What did other studies find?

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Most important risk factor for hepatitis C is injecting drug use
Although the overall prevalence of hepatitis antibodies was lower in prison entrants, the prevalence of these antibodies in entrants previously in prison was similar to that reported in the prison inmates, as was the prevalence in recidivist drug injectors.¹ In both surveys injecting drug use was by far the most important risk factor for hepatitis C, with injectors who reported sharing needles in prison or frequent current injecting being more likely to test positive (see full version of article on bmj.com). In both surveys about a fifth of injectors reported that they had started injecting in prison. Surveys in some Scottish prisons have reported similarly high initiation figures. ^{4 6 8}

Prevalence of hepatitis B in drug injectors entering Irish prisons was lower than in other countries
The prevalence of hepatitis B core antibodies (18%) in drug injectors entering Irish prisons was lower than the 52% and 43% reported in drug injectors entering Australian prisons, ^{9 10} and also lower than in drug injectors entering French prisons (37%).¹¹ Ireland has a programme of proactive hepatitis B vaccination in prisons, and the vaccination coverage is higher than reported in UK prisons.⁷ This may contribute to the lower than expected prevalence of hepatitis B in Irish prisoners. Offering the vaccine to all prisoners during committal procedures could further reduce the transmission of hepatitis B virus in Irish prisons.

Tattooing in prison may cause hepatitis C
Tattooing in prison was the only independent risk factor identified for the presence of hepatitis C antibodies in respondents who had never used injected drugs (see full version of article on bmj.com). Abildgaard and Peterslund reported the presence of hepatitis C antibodies in an individual with a tattoo but no other risk factors,¹² and Turnbull et al reported that 6% of prisoners interviewed had a tattoo done on their last occasion in prison and that half of these had shared tattooing equipment.¹³ Taken together, these findings suggest that tattooing may be responsible for transmission of hepatitis C in prison. It may be advisable to include a question on tattooing in future studies of viral prevalence.

	What are the limitations of our study?

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Conclusions from cross sectional surveys are limited. It is therefore not possible to deduce from this survey whether the higher infection rates in recidivist prisoners are because of their more chaotic drug use patterns (for example, a higher proportion of injectors previously imprisoned had started injecting more than three years earlier) or because of the previous exposure to prison. Increased risk associated with exposure to prison is probably because of the high risk injecting practices adopted in prison (such as sharing a small number of needles with a large and varied cohort of inmates) rather than spending time in prison in itself.

The validity of oral fluid assays is high except for the 80% sensitivity of the hepatitis C antibody test.¹ The prevalence of hepatitis C antibodies reported in this survey is therefore likely to be an underestimate of the true prevalence, which could be as high as 90% in injecting drug users entering Irish prisons. This is substantially higher than the prevalence reported in entrants to Australian prisons (64% and 66%). ^{9 10}

	What are the implications for practice?

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It is clear that both use of injected drugs and infection with hepatitis C virus are endemic in Irish prisons. As imprisonment leads to high risk practices, this survey points to the need for increased infection control and harm reduction measures in Irish prisons.

	Acknowledgments

We thank Una Cronin, Carrie Garavan, Geraldine McCullough, and Ailbhe Mealy for help with the fieldwork. We also thank the governors and staff of the prisons visited and especially the prisoners who participated in this study. We thank Linda Donovan and Josephine Morris at the Public Health Laboratory Service (PHLS), London, for laboratory testing, and Noel Gill and Andrew Weild for support and sharing of information. Finally, we thank Alan Kelly of the Department of Community Health and General Practice, TCD, for statistical advice.

Contributors: See bmj.com

	Footnotes

Funding: The Department of Justice, Equality and Law Reform, Republic of Ireland. The views expressed in this paper are those of the authors and not necessarily those of the Department of Justice, Equality and Law Reform, Republic of Ireland.

Competing interests: FB has contributed to policy development on prison health for the Labour Party (Ireland) and, until recently, was a part time prison medical officer. JB is a member of the National Drugs Strategy Team (Ireland).

	References

Top Abstract Why we carried out... What were the main... How did we perform... What were the detailed... What did other studies... What are the limitations... What are the implications... References

1.	Allwright S, Bradley F, Long J, Barry J, Thornton L, Parry J. Prevalence of antibodies to hepatitis B, hepatitis C and HIV and risk factors in Irish prisoners: results of a national cross sectional survey. BMJ 2000; 321: 78-82[Abstract/Full Text].
2.	Bird AG, Gore SM, Jolliffe DW, Burns S. Anonymous HIV surveillance in Soughton Prison, Edinburgh. AIDS 1992; 6: 725-773[Medline].
3.	Bird AG, Gore SM, Burns SM, Duggie JG. Study of infection with HIV and related risk factors in young offenders' institution. BMJ 1993; 307: 228-231[Medline].
4.	Gore SM, Bird AG, Burns SM, Goldberg DJ, Ross AJ, Macgregor J. Drug injection and HIV prevalence in inmates of Glenochill prison. BMJ 1995; 310: 293-296[Abstract/Full Text].
5.	Bird AG, Gore SM, Cameron S, Ross AJ, Goldberg DJ. Anonymous HIV surveillance with risk factor elicitation at Scotland's largest prison, Barlinnie. AIDS 1995; 9: 801-808[Medline].
6.	Gore SM, Bird AG, Burns S, Ross AJ, Goldberg D. Anonymous HIV surveillance with risk-factors elicitation: at Perth (for men) and Cornton Vale (for women) Prisons in Scotland. Int J STD AIDS 1997; 8: 166-175[Medline].
7.	Weild A, Gill O, Bennett D, Livingstone S, Parry J, Curran L. Prevalence of HIV, hepatitis B and hepatitis C antibodies in prisoners in England and Wales: a national survey. Commun Dis Public Health 2000; 3: 121-126[Medline].
8.	Bird AG, Gore SM, Hutchinson SJ, Lewis SC, Cameron S, Burns S. Harm reduction measures and injecting inside prison versus mandatory drugs testingresults of a cross sectional anonymous questionnaire survey. BMJ 1997; 315: 21-24[Abstract/Full Text].
9.	Crofts N, Stewart T, Hearne P, Ping XY, Breschkin AM, Locarnini SA. Spread of bloodborne viruses among Australian prison entrants. BMJ 1995; 310: 285-288[Abstract/Full Text].
10.	Butler TG, Dolan KA, Ferson MJ, McGuinness LM, Brown PR, Robertson PW. Hepatitis B and C in New South Wales Prisons: prevalence and risk factors. Med J Aust 1997; 166: 127-130[Medline].
11.	Rotily M, Vernay-Vaisse C, Bouliere M, Galinier-Pujol A, Rousseau S, Obadia Y. HBV and HIV screening, and hepatitis B immunization programme in the prison of Marseille, France. Int J STD AIDS 1997; 8: 735-759[Medline].
12.	Abildgaard N, Peterslund NA. Hepatitis C virus transmitted by tattooing needle. Lancet 1991; 338: 460[Medline].
13.	Turnbull PJ, Dolan KA, Stimson GV. Prisons HIV and AIDS: risks and experiences in custodial care. Horsham: AVERT, 1991.

(Accepted 30 May 2001)

Commentary: efficient research gives direction on prisoners' and the wider public healthexcept in England and Wales.

Sheila M Bird, senior statistician. 

MRC Biostatistics Unit, Cambridge CB2 2SR

sheila.bird{at}mrc-bsu.cam.ac.uk

Cost efficient, prison based medical research ^{1 2} has made an impact on enlightened prison services, such as in Scotland and Ireland, where short-course hepatitis B immunisation is offered. Long et al provide evidence of success: in the Republic of Ireland eight out of 10 recidivist prisoners who were vaccinated against hepatitis B had received their immunisation in prison. Clearly, community services have some catching up to do. Despite being limited to prisoners with longer sentences, hepatitis B immunisation in Irish prisons had reached a quarter of recidivists. Long et al suggest that offering it to all prisoners during committal procedures, as occurs in Scotland, could further reduce transmission of hepatitis B.

By contrast, the prison service in England and Wales has still failed to implement its strategy to provide hepatitis B immunisation for prisoners at risk of infection, despite research evidence of the need for it,³ nor has it provided sterilisation tablets for inmates to clean needles and injecting equipment. By not condemning the prison service's procrastination on harm reduction,⁴ the Department of Health condones this situation. Sir David Ramsbotham, the former chief inspector of prisons, had higher, fearless expectations for the treatment of prisoners⁵ but was let go.

Long et al have successfully applied the same methods (unattributable saliva sample plus self completion questionnaire) to prison entrants as they had done recently to inmates in the same prisons⁶a methodological first in prison based research into HIV infection and hepatitises related to injecting drugs. Notably, a third of prison entrants had never been in prison before; only 7% (14/197) of these first time entrants reported ever injecting drugs compared with 40% (157/394) of recidivist entrants, and 43% (509/1178) of prison inmates.⁶

The table shows the prevalence of prison inmates who had ever injected drugs among those who participated in nine first "willing anonymous salivary HIV/hepatitis C" (WASH-C) studies in Scotland: 26% (765/2895) of inmates had never been in prison before. The combined Scottish and Irish data point to a doubling of prevalence of injectors between first and subsequent incarceration, with a further doubling thereafter.

This is a critical observation operationally because prison services know how many times an inmate has been in prison before but not necessarily his or her history of injecting drugs. Since the proportion of inmates with a history of injecting rises steeply with the number of previous incarcerations, most injectors with rehabilitation needs will be found among those who have been inside two or more times before. Prevention initiatives, including how to avoid being initiated into injecting drugs, are best directed at those with most to gainfirst and second time prisoners, especially young offenders.

For research, the high recidivism and low prevalence of injectors in first time prison entrants make prisons and young offenders institutions a cost efficient setting in which to monitor trends in recidivists' incidence of initiation into injecting of drugs (and incidence of hepatitis C among injectors). A suitable paired sample method has been devised, ^{7 8} and Long et al have shown that its application in the 48 hours after prisoners' committal to prison could work well. Questions such as what characterises new initiates into drug injecting could be answered. Monitoring the incidence of initiation into injecting of drugs and the context of initiation (in or out of prison) is key to any drugs strategy and for reducing the transmission of hepatitis C.

Long et al also showed that carriage of hepatitis C by non-injectors was linked to their having been tattooed in prison. To reduce that risk, tattooists should not use the same device on inmates who inject drugs and then on non-injectors, the use of sterilisation tablets should be promoted, and the booking of sterile equipment be considered with appropriate safeguards for staff and prisoners.

Surveys of people arrested by the police have not enjoyed the high volunteer rates that prisoner surveys donearer 40% than 80%. ^{9 10} If answers to common questions are similar across different settings in the criminal justice system (people under arrest, prison entrants and inmates), future studies could concentrate on the setting where answers are available most cost efficiently. It is time for surveys of prisoners to address wider issues (on drugs, morbidity, and acquisitive crime) than risk factors for bloodborne viruses. Time indeed for a wider epidemiological research programme on prisoners' healtha prudent investment with likely dividends for prisoners' and public health (provided, of course, that coercion is avoided, confidentiality is secured, methods are acceptable to prisoners, and they are informed of outcomes¹¹).

	Footnotes

   Competing interests: I have published research on similar themes among Scottish prisoners and have a research interest in prisoners' health.

The full version of this article appears on bmj.com

	References

1.	Bird AG, Gore SM, Hutchinson SJ, Lewis SC, Cameron S, Burns S, for the European Commission Network on HIV infection and Hepatitis in prison. Harm reduction measures and injecting inside prison versus mandatory drugs tests: results of a cross sectional anonymous questionnaire survey. BMJ 1997; 315: 21-24[Abstract/Full Text].
2.	Gore SM, Bird AG, Cameron SO, Hutchinson SJ, Burns SM, Goldberg DJ. Prevalence of hepatitis C carriage in Scottish prisons: willing anonymous salivary hepatitis C surveillance linked to self-reported risks. Q J Med 1999; 92: 25-32.
3.	Weild AR, Gill ON, Bennett D, Livingstone SJM, Parry JV, Curran L. Prevalence of HIV, hepatitis B, and hepatitis C antibodies in prisoners in England and Wales: a national survey. Commun Dis Public Health 2000; 3: 121-126[Medline].
4.	Department of Health and Expert Working Group. Appendix G: application of guidance to the prison setting in hepatitis Cguidance for those working with drug users. London: DoH, 2001:46-48.
5.	HM Chief Inspector of Prisons (Sir David Ramsbotham). Patient or prisoner? London: Home Office, 1996.
6.	Allwright S, Bradley F, Long J, Barry J, Thornton L, Parry JV. Prevalence of antibodies to hepatitis B, hepatitis C, and HIV and risk factors in Irish prisoners: results of a national cross sectional survey. BMJ 2000; 321: 78-82[Abstract/Full Text].
7.	Gore SM, Bird AG, Burns SM. HIV epidemiology in prisons: anonymous voluntary HIV surveillance with risk factor elicitation. In: Liebling A, ed. Deaths in custody. Caring for people at risk. London: Whiting and Birch, 1996:114-142.
8.	Bird SM, Rotily M, Bird AG (deceased). Inside methodologies: for counting blood-borne viruses and injector-inmates' behavioural risks, with results from European prisons. Howard J Criminal Justice (in press).
9.	Bennett T. Drugs and crime: the results of the second developmental stage of the NEW-ADAM programme. Home Office research study 205. London: Home Office Research and Statistics Directorate, 2000.
10.	McKeganey N, Connelly C, Knepil J, Norrie J, Reid L. Interviewing and drug testing of arrestees in Scotland: a pilot of the arrestee drug abuse monitoring (ADAM) methodology. Edinburgh: Central Research Unit, Scottish Executive, 2000.
11.	Bird AG, Gore SM. Inside methodology: HIV surveillance in prisons. AIDS 1994; 8: 1345-1346[Medline].