Influence of provider experience on antiretroviral adherence and viral suppression

Michael A Horberg,1,2 Leo B Hurley,2,3 William J Towner,4 Michael W Allerton,3 Beth T Tang,5 Sheryl L Catz,6 Michael J Silverberg,2,3 Charles P Quesenberry31Mid-Atlantic Permanente Research Institute, Rockville, MD, USA; 2HIV Initiative, Kaiser Permanente, Oakland, CA, USA; 3Kaiser Permanente Northern California, Oakland, CA, USA; 4Kaiser Permanente Southern California, Los Angeles, CA, USA; 5Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA; 6Group Health Research Institute, Seattle, WA, USABackground and aim: Early in the combination antiretroviral therapy (cART) era, provider experience (as measured by panel size) was associated with improved outcomes. We explored that association and other characteristics of provider experience.Methods: We performed a retrospective cohort analysis in Kaiser Permanente California (an integrated health care system in the United States), examining all human immunodeficiency virus seropositive (HIV+) patients initiating a first cART regimen (antiretroviral therapy [ART]-na ve, N = 7071) or initiating a second or later cART regimen (ART-experienced, N = 3730) from 1996–2006. We measured ART adherence through 12 months (pharmacy fill and refill records) and determined HIV viral load levels below limits of quantification at 12 months. Provider experience, updated annually, was measured as (1) HIV panel size (0–10 patients as reference strata), (2) years treating HIV (less than 1 year as reference), and (3) specialty (noninfectious disease specialty, non-HIV expert as reference). We assessed associations by utilizing mixed modeling analyses (clustered by provider and medical center), controlling for patient age, sex, race/ethnicity, HIV risk behavior, hepatitis C coinfection, ART regimen class, and calendar year.Results: Among the ART-experienced, improved adherence was associated with greater years experience (mean increase 3.1% 2–5 years experience; 3.7% 5–10 years; 2.7% 11–20 years; P = 0.07, categorical). In adjusted analyses, viral suppression among ART-na ve was positively associated with panel size (odds ratio 26–50 patients: 1.31, P = 0.03, categorical), but negatively associated with years experience (18% less for greater than 100 patients; P = 0.003). No provider characteristic was significantly associated with improved adherence among ART-na ve or odds of maximal viral suppression among ART-experienced in adjusted analysis.Conclusions: Except for panel size and years experience among ART-na ve, provider characteristics did not significantly influence ART adherence or likelihood of