Publication Alert: Antiretroviral Refill Histories as a Predictor of Future Human Immunodeficiency Virus Viremia

The content below was provided by Darryl Sokpa, ’22 PharmD/MBA candidate at UNMC College of Pharmacy. He led a recently published study, collaborating with UNMC ID faculty Drs. Sara Bares and Nada Fadul, and mentored by UNMC ID pharmacist faculty Dr. Joshua Havens.

What prompted this study?

Adherence to antiretroviral therapy (ART) remains the cornerstone of treatment for HIV infection.  Many adherence metrics including subjective reporting, assessment of drug concentrations in dried blood spots (DBS)/hair/urine, novel technologies such as medication event monitoring systems, and the quantification of prescription refill histories as a percentage of days covered (PDC), have been evaluated in other studies.  While each of these adherence metrics has its own set of positive and negative attributes, PDC is arguable the easiest to collect, encompassing of all antiretrovirals, and can be used in real-time clinical decision-making. 

Our colleagues, Byrd et al, have explored using PDCs to evaluate association with viral suppression and to identify minimum PDC thresholds for current viral suppression both in aggregate and by ART regimen type.  We wanted to evaluate the use of PDC as a measure to assess future viral failure and to identify an associated PDC threshold level.  Additionally, we aimed to find predictive factors for low adherence levels under the identified PDC threshold level.

What are the key findings?

Our analysis found PDC was associated future viral failure in our cohort of 867 participants contributing to 1923 matched pairs (annual PDC matched to first reported HIV RNA in subsequent year).  PDC ≤52% was identified as a threshold level predictive of future HIV viremia in our analysis.  Sub-groups with higher odds of a PDC ≤52% were Black race, people experiencing homelessness, those with government-based insurance or uninsured, and those not in a committed relationship. 

What is the clinical take home message?

Our findings suggest PDC may be a useful clinical tool to identify patients at risk of future viral failure.  Additionally, our results may help clinicians better understand adherence trends to make better real-time clinical decisions and identify patients that may benefit from adherence support interventions and/or resistance testing.  Further, in conjunction with the findings of Byrd et al, we now have a key adherence zone bordered by the identified PDC thresholds (52-82%) to be further evaluated for long-term HIV outcomes.

Lastly, while the current literature using PDC as an adherence marker is encouraging, it is important to recognize the limitations of PDC values.  Most notably, PDC is still an imperfect adherence metric because it only represents pharmacy ART dispensations and not actual ingestion.   

Darryl Sokpa, pictured left, led this project. He is a ’22 PharmD/MBA candidate at UNMC College of Pharmacy.

Read the full article here.

Citation: Sokpa D, Lyden E, Fadul N, Bares SH, Havens JP. Antiretroviral Refill Histories as a Predictor of Future Human Immunodeficiency Virus Viremia. Open Forum Infect Dis. 2022 Jan 28;9(3):ofac024. doi: 10.1093/ofid/ofac024. PMID: 35187193; PMCID: PMC8849282.

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