Examining trends in the incidence of HIV infection among people with a history of drug use to inform an outbreak investigation and response: A retrospective cohort study.

Background: In the context of an outbreak of HIV among people who inject drugs in Glasgow, Scotland, identified in 2015, our objectives were to: (1) develop epidemiological methods to estimate HIV incidence using data linkage, and (2) examine temporal changes in HIV incidence to inform public health responses.

Methods: This was a retrospective cohort study involving data linkage of laboratory HIV testing data to identify individuals with a history of drug use. Person-years (PY) and Poisson regression were used to estimate incidence by time period (pre-outbreak: 2000-2010 and 2011-2013; early outbreak: 2014-2016; ongoing outbreak: 2017-2019).

A Statistical Model for Inference of Recent and Incident HIV Infection Using Surveillance Data on Individuals Newly Diagnosed With HIV Infection in Scotland.

Background: To inform global ambitions to end AIDS, evaluation of progress toward HIV incidence reduction requires robust methods to measure incidence. Although HIV diagnosis date in routine HIV/AIDS surveillance systems are often used as a surrogate marker for incidence, it can be misleading if acquisition of transmission occurred years before testing. Other information present in data such as antibody testing dates, avidity testing result, and CD4 counts can assist, but the degree of missing data is often prohibitive.