Evaluation of the scale-up of HIV testing among people who inject drugs in Scotland in the context of an ongoing HIV outbreak

Background: A large outbreak of HIV among people who inject drugs (PWID) has been ongoing in Glasgow city centre (GCC), Scotland since early 2015. The outbreak is associated with high levels of homelessness, cocaine injecting and injecting in public places. A key component of the public health response was the scale-up of HIV testing in a range of services engaged with PWID. Our aims were to: 1) evaluate the extent of and change in HIV testing over the course of the outbreak and 2) examine factors associated with reporting an HIV test. Methods: Self-report of an HIV test in the last 12 months was collected for 15,081 PWID interviewed in six national cross-sectional bio-behavioural surveys during 2008–2018. Multi-variate logistic regression was undertaken to determine trends in HIV testing by region of recruitment (GCC; rest of Glasgow; other Scottish city centres (SCC); and rest of Scotland) and outbreak period (pre: 2008-14; early: 2015-16; ongoing: 2017-18). Results: HIV testing increased across all regions and was most pronounced in GCC comparing the ongoing (67%) to the pre-outbreak period (33%) (aOR=4.68, 95% CI 3.23 to 6.77, p