The MACS/WIHS Combined Cohort Study (MWCCS) is a collaborative research effort that aims to understand and reduce the impact of chronic health conditions—including heart, lung, blood, and sleep (HLBS) disorders—that affect people living with HIV. MWCCS integrates two longstanding, longitudinal studies: the Multicenter AIDS Cohort Study (MACS) and the Women’s Interagency HIV Study (WIHS). The MACS began in 1984 as a longitudinal study of HIV-1 infection among gay and bisexual men in the United States and has enrolled more than 7,300 study participants at four clinical research sites, who were evaluated every six months; visit protocols included in-depth interviews, physical examinations, and collection of biological specimens for testing and repository storage. The WIHS began in 1993 as a multicenter longitudinal study to investigate the progression of HIV disease in women and has enrolled nearly 5,000 women (including HIV-positive women and a demographically similar group of HIV-negative women) at six clinical research sites. MACS and WIHS combined to form MWCCS in 2019.

Today, the MWCCS includes more than 4,000 active participants both with and without HIV and continues to recruit new participants, with study locations in Alabama, California, Georgia, Illinois, Maryland, New York, North Carolina, Ohio, Pennsylvania, and Washington, DC. The effort will study high-priority research on HIV outcomes, including prevalence, pathology, etiology, mechanisms, treatment, and prevention of morbidity and mortality related to HIV, its treatment, and the intersection of HIV and aging and the contextual factors common in the lives of those with HIV. Major areas of research focus include cardiovascular and pulmonary health, aging, cancer, neuropsychological and psychosocial health, and health disparities.