Comparison Between Guideline-Preferred and Nonpreferred First-Line HIV Antiretroviral Therapy
Published Online: June 19, 2014
Stephen S. Johnston, MA; Timothy Juday, PhD; Amanda M. Farr, MPH; Bong-Chul Chu, PhD; and Tony Hebden, PhD
More than 1 million people in the United States are currently infected with human immunodeficiency virus (HIV).1,2 While there is currently no cure for HIV, antiretroviral therapy (ART) can reduce HIV-associated morbidity and mortality.3 Based on accumulated clinical evidence, the March 2012 HHS guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents recommend 4 specific “preferred” ART regimens for ART-naïve patients.3 These are: efavirenz/tenofovir/ emtricitabine (EFV/TDF/FTC), ritonavir-boosted atazanavir + tenofovir/emtricitabine (ATV/r + TDF/ FTC), ritonavir-boosted darunavir + tenofovir/emtricitabine (DRV/r + TDF/FTC), and raltegravir + tenofovir/ emtricitabine (RAL + TDF/FTC).
These guideline-preferred ART regimens have been studied in randomized controlled trials and have been shown to confer the benefits of “optimal and durable virologic efficacy, favorable tolerability and toxicity profiles, and ease of use.”3 Comparatively, nonpreferred ART regimens (defined by guidelines as alternative, acceptable, or not recommended) may have “reduced virologic activity, lack of efficacy data from large clinical trials, or other factors (such as greater toxicities, pill burden, drug interaction potential, or need for additional testing).”3 Though the recommendations for preferred ART regimens are unambiguous, real-world evidence suggests that some healthcare providers nonetheless prescribe nonpreferred ART regimens.4,5 While the beneficial clinical aspects of guideline- preferred ART regimens are well described, the extent to which such benefits translate into improved ART adherence and persistence or lower healthcare expenditures in the ‘real world’ setting of routine clinical practice is poorly understood.
Among the various clinical settings in which HIV patients are commonly treated, the Medicaid setting is one of the most important. Medicaid is the largest source of health insurance for HIV patients living in the United States.6 Furthermore, as of January 2014, Medicaid coverage was expanded to cover all Americans with income below 133% of the federal poverty level, a provision of the Patient Protection and Affordable Care Act (PPACA). This change is predicted to significantly expand and improve access to, and quality of care for, HIV patients living in the United States.7-9 Thus, the objective of this study was to compare ART adherence and persistence and total healthcare expenditures in Medicaid- insured HIV patients initiating current guideline-preferred or nonpreferred first-line ART.
Setting and Data
The setting of this retrospective observational cohort study was routine clinical practice in a sample of Medicaid programs in 15 states of varying sizes and sociodemographic compositions across the United States. The Medicaid data were drawn from the 2004-2011 Truven Health Analytics MarketScan Multi-State Medicaid Database, which comprises covered inpatient medical, outpatient medical (including lab claims but not lab results), and outpatient pharmaceutical claims and encounter records, along with patient enrollment records and demographic information such as age, sex, and race. During the study period, over 25 million patients were represented in the database. Further public disclosure of identifying information about the state Medicaid programs covered by the database is restricted by confidentiality agreements between Truven Health Analytics and the data-contributing states.
The data contained in the Medicaid database are statistically deidentified and compliant with the Health Insurance Portability and Accountability Act privacy regulations. Therefore, Institutional Review Board approval and written informed consent were not required for this study.
Patients were identified and study variables were constructed from the data using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, Current Procedural Terminology codes, Healthcare Common Procedure Coding System codes, and National Drug Codes (NDCs), as appropriate.
HIV patients meeting all of the following inclusion criteria were selected into the study sample: initiated HIVrelated ART between January 1, 2007, and September 30, 2011 (the date of ART initiation was designated the index date); aged 18 to 64 years on the index date; had continuous enrollment with pharmacy benefits for 6 months prior to, and for at least 3 months following, the index date. Patients meeting any of the following exclusion criteria were excluded from the study sample: eligible for Medicare; showed evidence of HIV-related ART prescriptions any time prior to the index date, with data extending back to January 1, 2004, being used to check for prior ART use; showed any evidence of pregnancy or hepatitis B infection.
The study period comprised an index date, a baseline period, and a follow-up period. As noted above, the date of ART initiation was designated as the index date. This could have been the date of initiation on a single or combination of ART agents. Outpatient prescription claims for HIV-related ART were evaluated during the first 14 days after the index date (index date included) to establish ART regimens. The fixed 6-month period ending on the day before the index date was designated the baseline period. A variable-length period beginning on the index date was designated as the follow-up period. The duration of the follow-up period equaled the number of days from the index date until the first occurrence of (1) a prescription claim for an ART that was not part of the initiated ART regimen; (2) at least a 30-day continuous gap in any agent from the ART regimen (in which case, the end of the follow- up period was set to the last day on which the patient had possession of ART); (3) disenrollment from Medicaid benefits; (4) or the study end date of December 31, 2011.
Classification of Patients’ Initiated ART
Based upon the March 2012 HHS HIV treatment guidelines,3 patients were classified as initiating either guideline-preferred or nonpreferred first-line ART. This classification was applied for all data years and did not vary according to the preferred guidelines during the timeframe in which the patient actually initiated ART. As noted above, the March 2012 guideline-preferred ART regimens were: EFV/TDF/FTC, ATV/r + TDF/FTC, DRV/r + TDF/FTC, and RAL + TDF/FTC.
Study outcomes were ART adherence, ART persistence (ie, time to ART nonpersistence), and total healthcare expenditures. ART adherence and persistence were measured using ART prescription fill dates and days supplied. ART adherence was measured using the proportion of days covered (PDC), which was calculated as the proportion of days that patients had all components of their ART regimen “on hand” during the follow-up period. Accordingly, any days on which the patient did not possess all components of their ART regimen were counted as nonadherent days. ART adherence was dichotomized at 80% or greater (vs <80%) and 95% or greater (vs <95%). The 95% threshold was chosen on the basis of World Health Organization (WHO) HIV/AIDS program guidelines for antiretroviral therapy for HIV-infected adults and adolescents, which recommend maintenance of adherence levels at or above 95%.10 The 80% threshold was chosen on the basis of evidence showing that contemporary regimens may be slightly more “forgiving” to lapses in adherence.11 Time to ART nonpersistence was equal to the duration of the follow-up period. Patients were flagged as being nonpersistent if their follow-up period terminated with a filled prescription claim for an ART that was not part of the initiated first-line ART regimen or at least a 30-day continuous gap in therapy for any agent within the initiated first-line ART regimen. Patients were flagged as being censored if they were not flagged as being nonpersistent.
Healthcare utilization and expenditures were measured for all causes throughout the follow-up period and were summarized as per patient per month (PPPM) to account for variability in the duration of follow-up. Healthcare utilization and expenditures were categorized by place of service and included inpatient admissions, emergency department (ED) visits, outpatient office visits, outpatient laboratory services, other outpatient services, and pharmacy. Healthcare expenditures were expressed in 2011 constant dollars, adjusted using the Medical Care component of the Consumer Price Index.12 Healthcare expenditures included the gross covered payments for all healthcare services or products (ie, the amount eligible for payment after applying pricing guidelines such as fee schedules and discounts, but including deductibles, copayments, and coordination of benefits).
Covariates were measured to describe the study sample and to adjust for across-group differences in the multivariable models. These included demographics such as age, sex, and race; clinical characteristics such as proxies of overall health status and specific comorbidities; and ART regimen characteristics such as the number of ART agents in the initiated regimen and the components of the initiated regimen. The full listing of covariates is provided within the results tables.
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