Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study.
BACKGROUND
Results of cohort studies and mathematical models have suggested that increased coverage with highly active antiretroviral therapy (HAART) could reduce HIV transmission. We aimed to estimate the association between plasma HIV-1 viral load, HAART coverage, and number of new cases of HIV in the population of a Canadian province.


METHODS
We undertook a population-based study of HAART coverage and HIV transmission in British Columbia, Canada. Data for number of HIV tests done and new HIV diagnoses were obtained from the British Columbia Centre for Disease Control. Data for viral load, CD4 cell count, and HAART use were extracted from the British Columbia Centre for Excellence in HIV/AIDS population-based registries. We modelled trends of new HIV-positive tests and number of individuals on HAART using generalised additive models. Poisson log-linear regression models were used to estimate the association between new HIV diagnoses and viral load, year, and number of individuals on HAART.


RESULTS
Between 1996 and 2009, the number of individuals actively receiving HAART increased from 837 to 5413 (547% increase; p=0.002), and the number of new HIV diagnoses fell from 702 to 338 per year (52% decrease; p=0.001). The overall correlation between number of individuals on HAART and number of individuals newly testing positive for HIV per year was -0.89 (p<0.0001). For every 100 additional individuals on HAART, the number of new HIV cases decreased by a factor of 0.97 (95% CI 0.96-0.98), and per 1 log(10) decrease in viral load, the number of new HIV cases decreased by a factor of 0.86 (0.75-0.98).


CONCLUSIONS
We have shown a strong population-level association between increasing HAART coverage, decreased viral load, and decreased number of new HIV diagnoses per year. Our results support the proposed secondary benefit of HAART used within existing medical guidelines to reduce HIV transmission.


BACKGROUND
Ministry of Health Services and Ministry of Healthy Living and Sport, Province of British Columbia; US National Institute on Drug Abuse; US National Institutes of Health; Canadian Institutes of Health Research.
Montaner
Julio S G
JS
British Columbia Centre for Excellence in HIV/AIDS, Providence Health Care, Vancouver, BC, Canada. jmontaner@cfenet.ubc.ca
Lima
Viviane D
VD
Barrios
Rolando
R
Yip
Benita
B
Wood
Evan
E
Kerr
Thomas
T
Shannon
Kate
K
Harrigan
P Richard
PR
Hogg
Robert S
RS
Daly
Patricia
P
Kendall
Perry
P
D023241:Antiretroviral Therapy, Highly Active; D001955:British Columbia / Q000453:epidemiology; D018791:CD4 Lymphocyte Count; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000276:immunology / Q000821:virology; D015497:HIV-1; D006801:Humans; D012367:RNA, Viral / Q000097:blood; D019562:Viral Load
D012367:RNA, Viral