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HIV infection continues to be a major health concern although current drug treatments, which are based on combinations of drugs, are generally very effective and an increasing proportion or HIV-infected individuals are living to older age. However, some individuals have a poor response to treatment, largely due to an inability to tolerate their drugs, poor adherence to therapy or the development of HIV strains that are resistant to the drugs used.

As the HIV epidemic has increased in size, and mortality rates have dropped, the HIV-infected population in the UK has become more diverse. The UK CHIC Study makes it possible to conduct research using information collected on different groups of people infected with HIV in the UK. For example, older people now make up an increasing proportion of those with HIV, and they can have different health-care requirements. Also, the way that an individual's immune system responds to treatment for HIV varies with age, and the UK CHIC study data will enable investigation of the possible adverse effects of long-term drug treatment in an older population that may have other non-HIV related health problems.

HIV infection may contribute to an increased risk of several serious events that had previously been thought to be unrelated to HIV, including certain cancers, cardiovascular disease and liver failure. Research suggests that earlier treatment for HIV may have a greater impact on mortality than previously anticipated, so there is likely to be a move towards starting HIV treatment earlier. The drugs used and the way that these drugs are combined have changed over time. One of the key aims of the UK CHIC study is to use the data to monitor the way people's health responds to drug treatment, both in those that are new to taking ani-HIV drugs and in those who are already on treatment.


Study Design

Centres participating in the UK CHIC Study provide electronic data on eligible patients annually. The study collates information that is routinely collected by a clinic as part of a patient's HIV care, no additional study specific data or visits are required.

Data collected include patient demographics, information on clinical events (AIDS diagnoses and deaths), the results of various laboratory tests (CD4/CD8 counts and percentages, HIV RNA levels and laboratory measures of drug toxicity), antiretroviral drug use (date of starting and stopping each drug) and hepatitis co-infection. The data are held in a secure integrated relational database. All data are pseudonymised and it is not possible to identify individual patients from the datasets that are provided to the co-ordinating centre. After data quality checks and cleaning, each of the centres' datasets are combined, and records thought to belong to the same individual attending different clinics are merged using computer programmes. A final dataset is prepared annually, and only data items relevant to specific agreed analyses are made available to study collaborators.

Data from the UK CHIC Study are linked to HIV drug resistance test data in the UK HIV Drug Resistance Database, to the UK Seroconverter Register (CASCADE), CHIPS, and to HIV surveillance data at the Health Protection Agency.


Study Outputs

Members of the UK CHIC steering committee are encouraged to submit research proposals for analyses using UK CHIC data. Our study outputs are largely in the form of research presentations at national and international meetings, followed by publications in peer-reviewed journals. Summaries of published studies regularly appear in the HIV community press.



The UK CHIC Study has received project grant support from the Medical Research Council (MRC) from 2001 to 2014. In August 2014, the UK CHIC Study and the UK HIV Drug Resistance Database (UK HDRD) were jointly awarded a further 5 years of support from the MRC, enabling the projects to continue until August 2019.