Abstract / Description of output
Aims: To assess whether a simple, routinely available measure of
adherence to antiretroviral therapy (ART) – the proportion of days
covered by drug prescriptions in the previous 6 months – predicted viral
rebound at the next HIV viral load (VL), in patients who were previously
virologically suppressed.
Methods: The analysis was performed on a cohort of HIV-infected
individuals. Each drug coverage–VL episode consisted of a 6 month
period immediately prior to a VL<50 copies/mL (time-zero) over which
drug coverage was assessed. It was required that the patient had been
continuously on ART throughout the period, with VL<50 copies/mL. The
next VL after time-zero was used to assess the outcome (whether
rebound, defined as >200 copies/mL). Drug coverage was calculated as
the proportion of days that the individual had a valid prescription for at
least three antiretroviral drugs (ARVs). Each patient could contribute
more than one episode to the analysis. Poisson regression was used to
describe the effect of prescription coverage on the probability of
rebound.
Results: Three hundred and seventy-six (2.4%) VL rebounds occurred in
15660 ‘drug coverage – VL episodes’, after a median of 2.7 years on ART
(interquartile range [IQR]:1.3–4.6). The median time from time-zero to
the subsequent VL measurement was 94 days (IQR: 73–119). Coverage
was 100% for 37% of episodes, 96–99% for 18% of episodes and below
60% for only 5% of episodes. The risk ratio (RR) of rebound associated
with a 10% increment in prescription coverage was 0.91 (95% CI: 0.87–
0.95), which was unaffected by adjusting for the potential confounding
variables (RR = 0.93; 95%CI: 0.88–0.97). The results were similar when
coverage by at least one drug was considered sufficient. When restricted
to regimens in common use (PI/r or NNRTI: 8466 drug-coverage
episodes and 185 rebound events) the adjusted RR was 0.92 (95% CI:
0.85–0.99).
Conclusions: ARVs prescription coverage assessed at the time of a VL
measure in patients with undetectable VL seems to be clinically useful
for predicting VL rebound on the next measured VL
Original language | English |
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Pages (from-to) | 21 |
Number of pages | 1 |
Journal | HIV Medicine |
Volume | 10 |
Issue number | 1 |
Publication status | Published - 1 Apr 2009 |