title: A Comparison of Methods for Analyzing Viral Load Data in Studies of HIV Patients.
abstract: HIV RNA viral load (VL) is a pivotal outcome variable in studies of HIV infected persons. We propose and investigate two frameworks for analyzing VL: (1) a single-measure VL (SMVL) per participant and (2) repeated measures of VL (RMVL) per participant. We compared these frameworks using a cohort of 720 HIV patients in care (4,679 post-enrollment VL measurements). The SMVL framework analyzes a single VL per participant, generally captured within a "window" of time. We analyzed three SMVL methods where the VL binary outcome is defined as suppressed or not suppressed. The omit-participant method uses a 8-month "window" (-6/+2 months) around month 24 to select the participant's VL closest to month 24 and removes participants from the analysis without a VL in the "window". The set-to-failure method expands on the omit-participant method by including participants without a VL within the "window" and analyzes them as not suppressed. The closest-VL method analyzes each participant's VL measurement closest to month 24. We investigated two RMVL methods: (1) repeat-binary classifies each VL measurement as suppressed or not suppressed and estimates the proportion of participants suppressed at month 24, and (2) repeat-continuous analyzes VL as a continuous variable to estimate the change in VL across time, and geometric mean (GM) VL and proportion of participants virally suppressed at month 24. Results indicated the RMVL methods have more precision than the SMVL methods, as evidenced by narrower confidence intervals for estimates of proportion suppressed and risk ratios (RR) comparing demographic strata. The repeat-continuous method had the most precision and provides more information than other considered methods. We generally recommend using the RMVL framework when there are repeated VL measurements per participant because it utilizes all available VL data, provides additional information, has more statistical power, and avoids the subjectivity of defining a "window."
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Rose
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Lytt
authors.initials: L
authors.lastname: Gardner
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Jason
authors.initials: J
authors.lastname: Craw
authors.affiliation: ICF Macro International, Inc., Atlanta, GA, United States of America.
authors.forename: Sonali
authors.initials: S
authors.lastname: Girde
authors.affiliation: Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wawrzyniak
authors.affiliation: Department of Health Policy & Management, Boston University School of Public Health, Boston, MA, United States of America; Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine, Boston, MA, United States of America; Center for Healthcare Organization and Implementation Research, ENRM VA Hospital, Bedford, MA, United States of America.
authors.forename: Mari-Lynn
authors.initials: ML
authors.lastname: Drainoni
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, TX, United States of America.
authors.forename: Jessica
authors.initials: J
authors.lastname: Davila
authors.affiliation: STAR Clinic, Department of Medicine, SUNY Downstate Medical Center, Brooklyn, NY, United States of America.
authors.forename: Jack
authors.initials: J
authors.lastname: DeHovitz
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
authors.forename: Jeanne C
authors.initials: JC
authors.lastname: Keruly
authors.affiliation: Department of Biostatistics, University of Alabama-Birmingham School of Public Health, Birmingham, AL, United States of America.
authors.forename: Andrew O
authors.initials: AO
authors.lastname: Westfall
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Gary
authors.initials: G
authors.lastname: Marks
mesh_terms: D000293:Adolescent; D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D005260:Female; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy / Q000821:virology; D006801:Humans; D008297:Male; D012367:RNA, Viral / Q000097:blood; D019562:Viral Load; D055815:Young Adult
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral