BACKGROUND

Adherence to effective antiretroviral therapy (ART) is essential to achieve long-term viral suppression in patients with HIV-1. Single-tablet regimens (STRs) have improved adherence and decreased health care costs and hospitalizations, but previous study results suggest that the relationship between ART adherence and health care costs and utilization is complex.

OBJECTIVE

To assess ART adherence trends in patients with HIV-1 to determine if differences in utilization, demographics, and overall costs exist among patients with varying levels of medication adherence.

METHODS

This retrospective study analyzed medical and pharmacy claims data from an administrative claims database between January 1, 2007, and June 30, 2016, for Medicaid or commercially insured patients continuously enrolled for ≥ 6 months before and ≥ 15 months after the index date (date of first medical claim with an HIV diagnosis or pharmacy claim for HIV ART medication between July 1, 2007, and June 30, 2014). Qualifying patients were aged ≥ 18 years with a diagnosis of HIV-1 infection or at least 1 pharmacy claim for HIV ART at index and at least 2 pharmacy claims during the follow-up period. Patients were categorized on the basis of adherence as measured by proportion of days covered (PDC; ≥ 95%, highly adherent; < 95%, less adherent) and treatment with an STR or multiple-tablet regimen (MTR). Commercially insured patients were stratified by duration of follow-up data (< 3 or ≥ 3 years). There were not enough Medicaid patients for follow-up analysis. Outcomes of interest were ART adherence and annual medical and pharmacy utilization and costs. Descriptive statistics were generated, and health care resource utilization and costs were reported as annual averages. Chi-square and t-tests were used to examine differences between the cohorts.

RESULTS

A total of 332 Medicaid patients and 1,698 patients insured commercially met inclusion criteria. Adherence to ART medication (mean PDC) during the first 15 months was lower in Medicaid patients (65%) versus commercial patients (79%; P < 0.0001). Patients treated with STRs comprised 47% and 37% of patients in the < 3-year and ≥ 3-year follow-up cohorts, respectively. More STR patients achieved ≥95% adherence than MTR patients (< 3-year follow-up, 53% vs. 39%; ≥ 3-year follow-up, 61% vs. 45%; P < 0.001). In both follow-up cohorts, less adherent patients had higher mean annual medical costs, and results were significant for patients with ≥ 3-year follow-up ($8,224 vs. $3,097; P = 0.0007). These results were largely driven by savings in mean annual inpatient costs among the highly adherent patients in both cohorts (< 3-year follow-up, -$2,525 [P = 0.0003]; ≥ 3-year follow-up, -$815 [P < 0.001]).

CONCLUSIONS

Patients on STRs were more adherent than patients on MTRs regardless of length of follow-up. Better adherence was associated with significant inpatient cost savings. The relationship between adherence and total medical costs is nuanced depending on the duration of follow-up.

DISCLOSURES

This study was funded by ViiV Healthcare, which participated in protocol development, the analysis plan, and interpretation of results but did not have final approval on the decision to publish. Kangethe, Polson, Lord, and Evangelatos are employees of Magellan Rx Management, which was contracted by ViiV Healthcare to conduct the research for this study. Oglesby is an employee of ViiV Healthcare and owns stock in GlaxoSmithKline. Data from this study were previously presented at AMCP Nexus; October 16-19, 2017; Dallas, TX.