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  10th International Congress on Drug Therapy in HIV Infection
November 7-11, 2010
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More Drugs in Regimen--Not Just More Pills--Hurt Adherence
  Tenth International Congress on Drug Therapy in HIV Infection, November 7-11, 2010, Glasgow
Mark Mascolini
Having more antiretroviral products in a regimen more than tripled the risk of poor adherence in a single-center study in Dublin [1]. In the same 130-person analysis, a higher bill burden did not threaten resistance, but worse depression did.
Clinicians at Dublin's Mater Misericordiae University Hospital and colleagues at other sites prospectively studied 130 people from October 2008 to February 2009. They assessed adherence by the AIDS Clinical Trials Group adherence questionnaire, which includes questions about the number of missed doses in the past 4 days and adherence with the daily schedule (including timing and food requirements). The investigators assessed depression by the Centre for Epidemiological Studies depression score (CES-D); a higher score indicates worse depression. They defined suboptimal adherence as less than 95% adherence. Study participants also answered questions on potential predictors of poor adherence.
The study group had a median age of 38 years, 35 study participants (27%) were women, and 118 (91%) had a viral load below 50 copies. Median CD4 count stood at 389. While 60% were born in Ireland, 33% were born in Africa. Proportions using one, two, three, or four antiretroviral agents were 16%, 34%, 48%, and 2%. The researchers did not report what proportions were taking their first versus later regimens.
Thirty-six study participants (28%) had suboptimal adherence. Of 49 variables assessed as possible contributors to poor adherence, only three differed significantly in people with 95% or better adherence versus suboptimal adherence in multivariate analysis:
-- Median number of antiretroviral products: 2 (with 95% adherence) versus 3, P < 0.01
-- Median number of missed clinic visits: 1 (with 95% adherence) versus 3, P < 0.01
-- Median CES-D depression score: 4 (with 95% adherence) versus 8, P < 0.05
Taking more antiretroviral products daily more than tripled the risk of suboptimal adherence (odds ratio [OR] 3.45, 95% confidence interval [CI] 1.48 to 8.54), missed clinic visits boosted the poor adherence risk 45% (OR 1.45, 95% CI 1.16 to 1.81), and a higher (worse) depression score raised the risk 14% (OR 1.14, 95% CI 1.01 to 1.28).
The researcher believe this is the first study to isolate the number of antiretroviral products, rather than bill burden or dosing schedule, as the strongest predictor of faltering adherence. Although a link between spotty clinic attendance and poor adherence is intuitive, the investigators are not aware of other studies that have made this association. They note that adherence was generally high in this cohort, even though 30% had been infected through injection drug use.
A larger study presented at this conference and reported separately by NATAP found that a one-pill-daily regimen independently improved chances of attaining at least 95% adherence and lowered chances of getting admitted to the hospital [2].
1. Boyle C, Wilson A, Treacy G, et al. Antiretroviral complexity as a predictor of adherence. Tenth International Congress on Drug Therapy in HIV Infection. November 7-11, 2010. Glasgow. Abstract P121.
2. Sax PE, Meyers JL, Mugavero MJ, Davis KL. Adherence to antiretroviral treatment regimen and correlation with risk of hospitalization among commercially insured HIV patients in the US. Tenth International Congress on Drug Therapy in HIV Infection. November 7-11, 2010. Glasgow. Abstract O113.