BRIEF REPORT 538 • CID 2021:73 (1 August) • BRIEF REPORT Clinical Infectious Diseases Correspondence: M.-J. Milloy, Canopy Growth professor of cannabis science, Assistant Professor, Department of Medicine, University of British Columbia; Research scientist, BC Centre on Substance Use, 1045 Howe St, Vancouver, BC, V6Z 2A9, Canada (bccsu-mjm@bccsu. ubc.ca). Clinical Infectious Diseases ® 2021;73(3):538–41 © The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com. DOI: 10.1093/cid/ciaa1263 Te Veterans Aging Cohort Study (VACS) Index Predicts Mortality in a Community-recruited Cohort of People With Human Immunodefciency Virus (HIV) Who Use Illicit Drugs Hudson Reddon, 1,2 Cameron Grant, 1 Ekaterina Nosova, 1 Nadia Fairbairn, 1,3 Rolando Barrios, 4 Amy C Justice, 5,6 Seonaid Nolan, 1,3 M. Eugenia Socias 1,3 and M-J Milloy 1,3, 1 British Columbia Centre on Substance Use, Vancouver, BC V6Z 2A9, Canada, 2 CIHR Canadian HIV Trials Network, Vancouver, BC V6B 3E6, Canada, 3 Department of Medicine, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada, 4 British Columbia Centre for Excellence in HIV/AIDS, St Paul’s Hospital, Vancouver, BC V6Z 1Y6, Canada, 5 Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA, and 6 VA Connecticut Healthcare System, West Haven, Connecticut, USA Te Veterans Aging Cohort Study (VACS) index combines com- monly collected clinical biomarkers to estimate human immu- nodefciency virus (HIV) disease severity. Among a prospective cohort of people living with HIV who use illicit drugs (PWUD) (n = 948), we found that the VACS index was signifcantly asso- ciated with mortality over a 20-year study period. Keywords. VACS index; mortality; HIV; people who use drugs; Restricted Index. INTRODUCTION People living with human immunodeficiency virus (HIV) have increased inflammation and immune activation that persists even while receiving antiretroviral therapy (ART), which are strongly associated with morbidity and mortality [1]. The Veterans Aging Cohort Study (VACS) index was developed as a predictor of all-cause mortality among people living with HIV [2, 3]. Highly correlated with measures of systemic in- flammation, the VACS index is composed of measures of HIV mortality risk and indicators of comorbidity and organ system dysfunction [2–4]. HIV-positive people who use illicit drugs (PWUD) have not benefted equally from HIV treatment advancements. Te in- fammatory efects of illicit substance use may contribute to increased morbidity and mortality among this population [5]. Existing measures of HIV disease progression (eg, CD4+ cell count) sufer from well-known limitations. Employing the VACS index to evaluate mortality risk among HIV-positive PWUD may provide important information for research and clinical practice [3, 4]. Although substance use is a crucial risk factor for HIV disease progression, we are unaware of any study that has specifcally examined the application of the VACS index among HIV-positive PWUD. In light of these knowledge gaps and need to improve outcomes for people living with HIV who use illicit drugs, we sought to: (1) evaluate the association between the VACS index with rates of mortality among a pro- spective cohort of HIV-positive PWUD; and (2) compare its discriminative power to the restricted index [4]. METHODS The data for this investigation were collected from a prospec- tive cohort of people living with HIV and who use illicit drugs in Vancouver, Canada: The AIDS Care Cohort to Evaluate ex- posure to Survival Services (ACCESS) [6]. Individuals were eligible for ACCESS if they were: aged ≥18 years, HIV sero- positive, report using illicit drugs other than or in addition to cannabis (a controlled substance during the study period), res- ided in the Greater Vancouver Regional District, and provided informed consent at study enrollment. At baseline and every 6 months thereafer, participants pro- vided blood samples for hepatitis C virus (HCV) serology and HIV clinical monitoring (human immunodefciency virus type 1 [HIV-1] RNA plasma viral load [VL], CD4+ cell counts) and completed an interviewer-administered question- naire that elicited sociodemographic information, substance use patterns, engagement with health and social services, and other related exposures. Te University of British Columbia/ Providence Health Care Research Ethics Board approved the ACCESS study. Trough a confdential data linkage with the Drug Treatment Program of the British Columbia Centre for Excellence in HIV/AIDS, we accessed retrospective and prospective data for all ACCESS participants on: HIV-related measures (e.g., HIV VL, CD4+ cell counts) and other biological measures collected Received 27 April 2020; editorial decision 11 August 2020; accepted 27 August 2020; published online August 28, 2020.