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  10th International Congress on Drug Therapy in HIV Infection
November 7-11, 2010
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Good Adherence Lowers Hospital Risk 40% in Insured US Patients With HIV
  Tenth International Congress on Drug Therapy in HIV Infection, November 7-11, 2010, Glasgow
Mark Mascolini
Attaining 95% adherence to antiretroviral therapy lowered the risk of hospital admission almost 40% in a study of 7000 US patients with commercial or government health insurance [1]. Taking a one-pill-per-day antiretroviral regimen lowered the hospital admission risk significantly in these people.
Researchers from RTI Health Solutions, Brigham and Women's Hospital in Boston, and the University of Alabama at Birmingham analyzed the impact of daily pill count on adherence, and the impact of pill count and adherence on hospital admission, in the Life-Link claims database. The investigators grouped patients according to whether they took one, two, or three or more antiretroviral pills daily and whether they had 95% of better adherence determined by prescription refills. Everyone was taking two nucleosides and either a nonnucleoside, a protease inhibitor, a CCR5 antagonist, or an integrase inhibitor for at least 60 days between June 1, 2006 and December 31, 2008.
Of the 7073 people analyzed, 33% were taking one antiretroviral pill a day, 6% two pills a day, and 61% three or more pills a day. About 80% of these people were men, and age averaged about 44 years. About 85% had commercial health insurance, about 9% were self-employed and purchased their own insurance, and under 5% were covered by Medicare or Medicaid. Similar low proportions in each regimen group had mental health disorders (about 6%) or abused drugs or alcohol (about 14%). The one-pill-daily group had a higher proportion of previously untreated people (42%) than the two-pill group (25%) or the three-pill group (20%). Median treatment duration stood slightly above 300 days in all three groups.
While 47% taking one pill daily had 95% or better adherence, 41% taking two pills daily and 34% taking three or more pills daily attained that adherence level. Respective proportions with at least 90% adherence were 72%, 68%, and 63%.
To identify predictors of at least 95% adherence and hospital admission, the researchers devised a multivariate model that considered patient demographics, comorbidities, and whether they were taking their first antiretroviral regimen or a later regimen. This model determined that people taking one antiretroviral pill daily were 61% more likely to reach 95% adherence than people taking three or more pills daily (odds ratio [OR] 1.61, P < 0.001). Taking two pills daily also significantly favored 95% adherence compared with three or more pills daily, as did taking a first-line regimen. Drug or alcohol abuse lowered the chance of 95% adherence almost 50%, but having a mental disorder had no impact.
Regardless of regimen type, people attaining 95% adherence were significantly less likely to get admitted to the hospital. For people taking one pill daily, 6.6% with 95% adherence versus 11.4% without 95% adherence went to the hospital. For the two-pill group, those proportions were 6.6% versus 15.2%, and for the three-or-more-pill group 7.8% versus 12.1% (P < 0.001 for all three comparisons).
Multivariate analysis determined that people with 95% or better adherence were almost 40% less likely to go to the hospital during the study period than people with worse adherence, regardless of how many antiretroviral pills they took daily (OR 0.62, P < 0.001). In this analysis, having a mental disorder, abusing drugs or alcohol, or being a woman all independently upped the risk of hospital admission.
Adjusted rates of hospital admission were 7.7% for one-pill regimens, 9.9% for two-pill combos, and 9.9% for three or more pills (P = 0.003 versus one pill daily). Compared with people taking three or more pills daily, those taking one pill daily were more than 20% less likely to go to the hospital (OR 0.77, P < 0.01).
The findings may not apply to poorer or elderly US HIV patients, since under 5% in this study relied on Medicaid or Medicare. One meeting attendee argued that confounding by indication may color the results, if people who took one antiretroviral pill daily differed in important unmeasured ways from those taking two or more antiretroviral pills daily. The investigators noted that measuring adherence by prescription refill may overestimate adherence compared with other methods.
1. 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.