The HIV-CAUSAL Collaboration is a multinational consortia of HIV cohortsprospective observational studies of persons living with HIVfrom nine countries in Europe and the Americas. The research team includes investigators from each of the participating studies and from the coordinating center.

The investigators of the HIV-CAUSAL Collaboration love randomized trials, but also understand that trials cannot answer all important questions for the clinical management of HIV, and cannot answer some urgent questions in a timely manner. Because observational HIV cohorts will necessarily be used to inform clinical decisions, it is important that observational data sources are used in the best possible way. The HIV-CAUSAL Collaboration was created to tackle the difficult methodological problems that arise when conducting comparative effectiveness and safety research in HIV cohorts.

For over a decade, the HIV-CAUSAL Collaboration has been at the forefront of development and implementation of statistical methods to compare the effectiveness of clinical strategies using HIV cohorts. Some of the methods pioneered by the Collaboration, including inverse probability weighting of marginal structural models and the parametric g-formula, have transformed the analysis of HIV cohorts in the 21st century. Investigators now have at their disposal a powerful arsenal of tools to evaluate the effectiveness and safety of clinical strategies using observational data. Our methodological work supports the clinical research that studies novel problems in HIV research.

Besides being an incubator for new methodologies, the HIV-CAUSAL Collaboration conducts clinical HIV research designed to inform evidence-based guidelines and the planning of randomized trials. Findings from the HIV-CAUSAL Collaboration played a prominent role in the now largely settled discussions about when to start antiretroviral therapy. Our recent research has contributed to a better understanding of the effects of antiretroviral therapy on opportunistic infections, neurological conditions, and viral resistance, as well to the study of dynamic strategies for the treatment and monitoring of individuals living with HIV.

In addition, the Collaboration facilitates understanding and training in causal modeling across leading HIV observational research groups in Europe and the Americas.


Our research is supported by MERIT award R37 AI102634 (PI: Hernán) from the National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health.