title: Time above 1500 copies: a viral load measure for assessing transmission risk of HIV-positive patients in care.
abstract: OBJECTIVE
  We examined HIV transmission potential of patients in care by analyzing the amount of person-time spent above a viral load threshold that increases risk for transmission.
  
  
  METHODS
  Observational cohort and supplemental data.
  
  
  METHODS
  The cohort included HIV patients who received care at six HIV clinics in the United States, from 1 April 2009 to 31 March 2013, and had two or more viral load tests during this interval. Person-time (in days) above a viral load of 1500 copies/ml out of the total observation time was determined by inspecting consecutive pairs of viral load results and the time intervals between those pairs. The person-time rate ratios comparing demographic and clinical subgroups were estimated with Poisson regression.
  
  
  RESULTS
  The cohort included 14 532 patients observed for a median of 1073 days with a median of nine viral load records. Ninety percent of the patients had been prescribed antiretroviral therapy. On average, viral load exceeded 1500 copies/ml during 23% of the patients' observation time (average of 84 days per year, per patient). Percentage of person-time above the threshold was higher among patients who had more than a fourth of their viral load pairs exceeding a 6-month interval (34% of observation time), patients not on antiretroviral therapy (58% of time), new/re-engaging patients (34% of time), patients 16-39 years of age (32% of time), and patients of black race (26% of time).
  
  
  CONCLUSIONS
  HIV patients in care spent an average of nearly a quarter of their time with viral loads above 1500 copies/ml, higher among some subgroups, placing them at risk for potentially transmitting HIV to others.
authors.affiliation: aDivision of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia bDepartment of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama cDepartment of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland dState University of New York, Downstate Medical Center, Brooklyn, New York eDivision of Infectious Diseases, Miller School of Medicine, University of Miami, Florida fDepartment of Medicine, Boston University School of Medicine, Boston, Massachusetts gDepartment of Medicine, Baylor College of Medicine, and the Center for Innovations in Quality, Effectiveness and Safety, Michael E DeBakey Veterans Affairs Medical Center, Houston, Texas, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Marks
authors.forename: Lytt I
authors.initials: LI
authors.lastname: Gardner
authors.forename: Charles E
authors.initials: CE
authors.lastname: Rose
authors.forename: Anne
authors.initials: A
authors.lastname: Zinski
authors.forename: Richard D
authors.initials: RD
authors.lastname: Moore
authors.forename: Susan
authors.initials: S
authors.lastname: Holman
authors.forename: Allan E
authors.initials: AE
authors.lastname: Rodriguez
authors.forename: Meg
authors.initials: M
authors.lastname: Sullivan
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Giordano
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000635:transmission*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D018570:Risk Assessment; D014481:United States; D019562:Viral Load; D055815:Young Adult