Treatment durability and virological response in treatment-experienced HIV-positive patients on an integrase inhibitor-based regimen: an Australian cohort study.
BACKGROUND
Integrase inhibitors (INSTI) are a newer class of antiretroviral (ARV) drugs that offer additional treatment options for experienced patients. Our aim is to describe treatment durability and virological outcomes in treatment-experienced HIV-positive patients using INSTI-based regimens.


METHODS
All patients in the Australian HIV Observational Database who had received an INSTI-based regimen ≥ 14 days as well as previous therapy were included in the study. We defined two groups of treatment-experienced patients: (1) those starting a second-line regimen with INSTI; and (2) highly experienced patients, defined as having prior exposure to all three main ARV classes, nucleoside reverse transcriptase inhibitor, nonnucleoside reverse transcriptase inhibitors and protease inhibitors, before commencing INSTI. Survival methods were used to determine time to viral suppression and treatment switch, stratified by patient treatment experience. Covariates of interest included age, gender, hepatitis B and C co-infection, previous antiretroviral treatment time, patient treatment experience and baseline viral load.


RESULTS
Time to viral suppression and regimen switching from INSTI initiation was similar for second-line and highly experienced patients. The probability of achieving viral suppression at 6 months was 77.7% for second-line patients and 68.4% for highly experienced patients. There were 60 occurrences of regimen switching away from INSTI observed over 1274.0 person-years, a crude rate of 4.71 (95% CI: 3.66-6.07) per 100 person-years. Patient treatment experience was not a significant factor for regimen switch according to multivariate analysis, adjusting for relevant covariates.


CONCLUSIONS
We found that INSTI-based regimens were potent and durable in experienced HIV-positive patients receiving treatment outside clinical trials. These results confirm that INSTI-based regimens are a robust treatment option.
Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.|Corresponding author. Email: ndelamata@kirby.unsw.edu.au.
Nicole L
NL
De La Mata
Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.
David A
DA
Cooper
School of Medicine and Dentistry, James Cook University, Townsville, Qld 4811, Australia.|University of Melbourne, Parkville, Vic. 3010, Australia.|Cairns Sexual Health Service, Cairns, Qld 4870, Australia.
Darren
D
Russell
The Albion Centre, Sydney, NSW 2010, Australia.|School of Public Health and Community Medicine, UNSW Australia, Sydney, NSW 2052, Australia.
Don
D
Smith
Monash Health, Infectious Disease, Melbourne, Vic. 3168, Australia.|Monash Health, Australia Department of Medicine, Melbourne, Vic. 3168, Australia.|Monash University, Australia Department of Infectious Diseases, Melbourne, Vic. 3800, Australia.
Ian
I
Woolley
Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.|Gold Coast Sexual Health Clinic, Miami, Qld 4215, Australia.
Maree O
MO
Sullivan
Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.
Stephen
S
Wright
Kirby Institute, UNSW Australia, Wallace Wurth Building, Sydney, NSW 2052, Australia.
Matthew
M
Law
regimen switch; time to treatment switch; viral load