Anonymous HIV surveillance with risk factor elicitation at Scotland's largest prison, Barlinnie

To determine prevalence of HIV infection and risk behaviours among male inmates of Her Majesty's Prison (HMP) Barlinnie, Glasgow, Scotland on 8-9 September 1994.

Cross-sectional study: voluntary, anonymous HIV surveillance (using saliva samples) of all inmates and linked self-completion risk-factor questionnaire.

Of 1073 prisoners available to participate, 985 (92%) completed a risk-factor questionnaire and 982 salivettes were received for testing, of which 978 were tested for HIV antibodies (four were dry samples); 928 questionnaires passed logical checks for consistency.

HIV prevalence on saliva testing, related risk behaviours and ratio of overall-to-disclosed HIV prevalence. Proportion of all inmates who have ever injected drugs, ever injected inside prison, started injecting inside, ever had acute hepatitis, had a recent personal HIV test (since January 1993).

Nine saliva samples [eight injecting drug users (IDU), one recognized other risk] out of 978 were HIV-antibody-positive (three presumptively from known HIV-infected inmates). Overall HIV prevalence was estimated at 1% compared with a known prevalence of 0.4%, giving an overall-to-disclosed HIV prevalence ratio of 2.6 in HMP Barlinnie in September 1994. A higher proportion of prisoners from Glasgow (48%) than elsewhere (19%) were IDU. Year of first injection was also different by residence with 23% of Glasgow IDU having first injected after 1988 compared with 45% of IDU from elsewhere, mainly West and South Scotland. Half the IDU inmates reported having injected while incarcerated and 6% had started to inject while incarcerated. Ten per cent of all prisoners and 20% of IDU inmates had had a personal HIV test since January 1993. Logistic regression showed that there was a significant deficit of recent HIV test uptake by Glasgow residents (odds ratio, 0.5; 95% confidence interval, 0.27-0.89), that IDU were more likely to have had treatment for a sexually transmitted disease, and that IDU who had injected inside and those whose injecting career began prior to 1989 were more likely to have had acute hepatitis.

A consistent harm-reduction policy is needed across prisons in the United Kingdom to avoid transmission of blood-borne viral infections. Drug injecting inside prison is common, a proportion of IDU inmates having first injected drugs while in prison, and much higher rates of hepatitis have been reported in association with injecting while incarcerated compared with that for IDU who only injected outside prison.