Clinical and economic outcomes of nonadherence to highly active antiretroviral therapy in patients with human immunodeficiency virus.

BACKGROUND: Nonadherence with highly active antiretroviral therapy (HAART) is common in typical human immunodeficiency virus (HIV) patient care settings, but the consequences have not been well described. This study aimed to quantify the clinical and economic effects of nonadherence and estimate the cost-effectiveness of improving adherence in treatment-naive HIV patients. METHODS: A Markov model was developed to project quality-adjusted life expectancy and direct medical costs for patients on an initial once-daily regimen of efavirenz, lamivudine, and stavudine XR. The model compared 2 adherence scenarios: "ideal" (based on clinical trials) and "typical" (based on observational studies in actual practice). Disease progression was a function of viral load, CD4 count, and adherence. Data on HIV natural history, treatment benefits, costs, and utilities were derived from the literature. RESULTS: With typical adherence, patients lose 1.2 quality-adjusted life years (QALYs) that could be gained with ideal adherence. Improving adherence to ideal levels is cost-effective at 29,400 US dollars/QALY gained. As much as 1,600 US dollars/y per patient could be spent on an intervention to improve adherence to ideal levels, and the incremental cost-effectiveness would remain less than 50,000 US dollars/QALY gained. A cost-effectiveness ratio of 50,000 US dollars/QALY is a commonly accepted minimum standard for cost-effective medical interventions in the United States, although many experts believe this standard has drifted upwards over time. CONCLUSIONS: Typical adherence with HAART reduces quality-adjusted life expectancy by 12% compared with ideal adherence. Interventions to improve adherence appear to be a highly cost-effective use of resources.

Coronary heart disease in HIV-infected individuals.

It is currently unknown whether there is an increased risk of coronary heart disease (CHD) in patients with HIV infection. In addition, the contribution of antiretroviral therapy (ART) to CHD risk has not been quantified. We reviewed administrative claims data for HIV-infected and -uninfected individuals from the California Medicaid population and compared the incidence of and relative risk (RR) for CHD using log-linear regression analyses between groups. The association between exposure to ART and CHD incidence was also assessed. Of 3,083,209 individuals analyzed, 28,513 were HIV-infected. The incidence of CHD among young men (up to age 34) and women (up to age 44) with HIV infection was significantly higher than that among non-HIV-infected individuals. The covariate-adjusted RR for the development of CHD in individuals receiving ART compared with those not receiving ART was 2.06 (P < 0.001) in HIV-infected individuals aged 18-33 years. There were no statistically significant associations between ART exposure and CHD in other age groups. CHD incidence appears accelerated among young HIV-infected individuals. Strategies to reduce CHD risk should be incorporated into HIV primary care.

Young HIV-infected adults are at greater risk for medication nonadherence.

This study sought to estimate rates of adherence to nucleoside reverse transcriptase inhibitors (NRTIs) during the first year of administration in the California Medicaid (Medi-Cal) population. A retrospective analysis of pharmacy claims data regarding NRTI prescription refills was employed to estimate adherence and persistence with therapy throughout 1 year in treatment-naive individuals. Adherence was defined as the proportion of days on which drugs were taken during the first 365 days of therapy, and persistence was assessed according to whether prescriptions were refilled over time within a tolerable threshold (60 days). A total of 2614 men and 1174 women exhibited a mean overall adherence rate of 53.0%, and 35.6% of individuals were persistent with therapy throughout the year. No differences in persistence or adherence rates by sex were detected (P =.30). The proportion of individuals with adherence of 80% or better was 26%. Age was found to be significant in adherence and persistence by chi-square examination (P =.001). We conclude that nonadherence can be a critical issue during the first year following initiation of therapy. Comprehensive adherence support programs may be required to maximize adherence, especially among subjects aged 18-24 years, and should be made available early in the course of therapy, or before it is initiated.

Adherence to oral antidiabetic therapy in a managed care organization: a comparison of monotherapy, combination therapy, and fixed-dose combination therapy.

BACKGROUND: Although medication adherence is one of the most important aspects of the management of diabetes mellitus, low rates of adherence have been documented. OBJECTIVE: This study sought to examine medication adherence among patients with diabetes mellitus in a managed care organization who were receiving antidiabetic monotherapy (metformin or glyburide), combination therapy (metformin and glyburide), or fixed-dose combination therapy (glyburide/metformin). METHODS: Medication adherence was evaluated through a retrospective database analysis of pharmacy claims. The adherence rate was defined as the sum of the days' supply of oral antidiabetic medication obtained by the patient during the follow-up period divided by the total number of days in the designated follow-up period (180 days). Health plan members were included in the analysis if they had an index pharmacy claim for an oral antidiabetic medication between August 1 and December 31, 2000, were continuously enrolled in the health plan, and were aged > or =18 years. A 6-month pre-index period was used to classify patients as newly treated or previously treated. Patients were grouped according to their medication-use patterns. RESULTS: After adjustment for potential confounding factors, including overall medication burden at index, there were no significant differences in adherence rates among 6502 newly treated patients receiving monotherapy, combination therapy, or fixed-dose combination therapy. Among the 1815 previously treated patients receiving glyburide or metformin monotherapy who required the addition of the alternative agent, resulting in combination therapy, adherence rates were significantly lower (54.0%; 95% CI, 0.52-0.55) than in the 105 patients receiving monotherapy who were switched to fixed-dose combination therapy (77.0%; 95% CI, 0.72-0.82). The 59 previously treated patients receiving combination therapy who were switched to fixed-dose combination therapy had a significant improvement in adherence after the switch (71.0% vs 87.0%; P < 0.001). CONCLUSIONS: In a managed care organization, previously treated patients receiving monotherapy with an oral antidiabetic medication who required additional therapy exhibited significantly greater adherence when they were switched to fixed-dose combination therapy compared with combination therapy. Patients receiving combination therapy who were switched to fixed-dose combination therapy exhibited significantly greater adherence after the switch.

Effects of once-daily and twice-daily dosing on adherence with prescribed glipizide oral therapy for type 2 diabetes.

BACKGROUND: We evaluated differences in adherence and persistence with prescribed therapy of once-daily (OD) dosing compared with twice-daily (BID) dosing of glipizide in patients with type 2 diabetes. METHODS: The study cohort was derived from a pharmacy benefit manager claims database. Patients new to extended-release gastrointestinal therapeutic system (GITS) and immediate-release glipizide therapy were identified and followed for 1 year. Adherence indices (AIs) were calculated and persistence curves were constructed. RESULTS: Adherence indices rates were 60.5% in the GITS OD cohort and 52.0% in the BID cohort. Rates of persistence at 12 months were 44.4% in the GITS OD cohort vs 35.8% in the BID cohort. CONCLUSION: Initiation of OD pharmacotherapy results in better adherence and persistence compared with a BID regimen, despite a greater daily pill burden in the OD cohort. These data suggest that dosing frequency exerts a greater impact on patient adherence and persistence than number of tablets per dose.