This paper describes the development of the UK Collaborative HIV Cohort (CHIC) Study. The aim of the study is to collate routinely collected data on HIV-infected individuals attending one of seven clinical centres in the UK since 1 January 1996, with the objectives of describing changes over time in the frequency of AIDS-defining illnesses, describing the uptake of and response to highly active antiretroviral therapy (HAART), and identifying factors associated with virological and immunological responses to HAART.
By December 2002, demographic, clinical and laboratory data had been collected on HIV-positive patients seen at six of the seven HIV centres. Missing and inconsistent data had been investigated and the datasets audited. Records identified as relating to the same patient had been merged, and cross-checks made with UK death registers to improve the accuracy of death reporting.
The cohort currently contains information on 13 833 individuals. Eighty-two per cent of the cohort are male, and the median age was 34 years at first follow-up. The main risk factors for HIV infection have been determined as sex between men (63%) and sex between men and women (24%). Twenty-five per cent of the cohort are known to have developed AIDS, and 8% have died.
The UK CHIC Study provides important information on the status of individuals infected with HIV in the UK, and provides a means to study the response to HAART and to monitor changes in the clinical event and death rates that have occurred since the introduction of HAART in the UK.