The cascade of HIV care in British Columbia, Canada, 1996-2011: a population-based retrospective cohort study.
BACKGROUND
The cascade of HIV care has become a focal point for implementation efforts to maximise the individual and public health benefits of antiretroviral therapy. We aimed to characterise longitudinal changes in engagement with the cascade of HIV care in British Columbia, Canada, from 1996 to 2011.


METHODS
We used estimates of provincial HIV prevalence from the Public Health Agency of Canada and linked provincial population-level data to define, longitudinally, the numbers of individuals in each of the eight stages of the cascade of HIV care (HIV infected, diagnosed, linked to HIV care, retained in HIV care, highly active antiretroviral therapy (HAART) indicated, on HAART, adherent to HAART, and virologically suppressed) in British Columbia from 1996 to 2011. We used sensitivity analyses to determine the sensitivity of cascade-stage counts to variations in their definitions.


RESULTS
13,140 people were classified as diagnosed with HIV/AIDS in British Columbia during the study period. We noted substantial improvements over time in the proportions of individuals at each stage of the cascade of care. Based on prevalence estimates, the proportion of unidentified HIV-positive individuals decreased from 49·0% (estimated range 36·2-57·5%) in 1996 to 29·0% (11·6-40·7%) in 2011, and the proportion of HIV-positive people with viral suppression reached 34·6% (29·0-43·1%) in 2011.


CONCLUSIONS
Careful mapping of the cascade of care is crucial to understanding what further efforts are needed to maximise the beneficial effects of available interventions and so inform efforts to contain the spread of HIV/AIDS.


BACKGROUND
British Columbia Ministry of Health, US National Institute on Drug Abuse (National Institutes of Health).
Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada; BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Bohdan
B
Nosyk
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada; School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada. Electronic address: jmontaner@cfenet.ubc.ca.
Julio S G
JSG
Montaner
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Guillaume
G
Colley
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Viviane D
VD
Lima
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Keith
K
Chan
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Katherine
K
Heath
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Benita
B
Yip
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada.
Hasina
H
Samji
Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada; BC Centre for Disease Control and Prevention, Vancouver, BC, Canada.
Mark
M
Gilbert
BC Centre for Excellence in HIV/AIDS, University of British Columbia, Vancouver, BC, Canada; Vancouver Coastal Health, Vancouver, BC, Canada.
Rolando
R
Barrios
Vancouver Coastal Health, Vancouver, BC, Canada.
Réka
R
Gustafson
Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.
Robert S
RS
Hogg
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001955:British Columbia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control; D006298:Health Services Administration / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011635:Public Health Administration / Q000706:statistics & numerical data* / Q000639:trends; D012189:Retrospective Studies; D055815:Young Adult