Objective: People on antiretroviral therapy are likely to be required to maintain good adherence throughout their lives. We aimed to investigate long-term trends in highly active antiretroviral therapy (HAART) adherence to identify the main predictors and to evaluate whether participants experience periods of low adherence (≤60%).
Methods: Participants in the Royal Free Clinic Cohort were followed from the date of start of HAART until the end of the last recorded ART prescription or death. Follow-up was divided into 6-month periods, and for each period, a value of adherence, measured as the percentage of days in the 6-month period covered by a valid prescription for at least three antiretroviral drugs, was calculated.
Results: Patients were assessed for drug coverage adherence for a median of 4.5 years [inter-quartile range (IQR) 2.4–7.2; maximum 9 years] covering a period up to 13 years from start of HAART. There was evidence of a slight increase in adherence over time [adjusted odds ratio (OR) of >95% adherence = 1.02 per year; 95% confidence interval (CI) 1.01–1.04; P = 0.0053]. Independent predictors of adherence were age, demographic group, calendar year period, drug regimen and previous virologic failures. The overall rate of at least one period of low adherence was 0.12 per person-year, but this rate decrease markedly over time to 0.01 in 2007/2008.
Conclusion: Adherence, as measured by drug coverage, does not decrease on average over more than a decade from start of HAART. This is encouraging, because it shows that patients could potentially maintain viral suppression for many years.
aHIV Epidemiology & Biostatistics Group, Research Department of Infection & Population Health, UCL Medical School, UK
bDepartment of HIV, Royal Free Hospital NHS Trust, London, UK.
Received 14 October, 2009
Revised 14 January, 2010
Accepted 2 February, 2010
Correspondence to Valentina Cambiano, HIV Epidemiology & Biostatistics Group, Research Department of Infection & Population Health, UCL Medical School, Royal Free Campus, Rowland Hill Street, London NW3 2PF, UK. E-mail: firstname.lastname@example.org