Pharmacist Interventions to Improve Specialty Medication Adherence: Study Protocol for a Randomized Controlled Trial

Abstract

Background: The effectiveness of specialty medications in complicated clinical conditions depends on adherence to therapy. However, specialty medications pose unique barriers to adherence.

Objective: This study aims to determine whether pharmacist interventions improve specialty medication adherence.

Methods: This is a single-center, pragmatic, randomized controlled trial ongoing since 10 May 2019 at an integrated health system specialty pharmacy. This study evaluates usual care compared with usual care plus patient-tailored adherence interventions. Study design and procedures were informed by focus groups with patients and specialty pharmacists. Patients at Vanderbilt Specialty Pharmacy with a proportion of days covered (PDC) < 90% in the previous 4 months are identified by a daily query of the electronic pharmacy database. A pharmacist reviews these patients' electronic health records to identify and exclude ineligible patients. Eligible patients are randomized evenly to the control or intervention arm and stratified by historical clinic nonadherence rates. Patients randomized to the intervention arm undergo a baseline assessment to clarify reasons for nonadherence and subsequently receive patient-tailored interventions based on their specific reasons. Interventions and follow-up are provided at the discretion of the intervening pharmacist. The primary outcome is PDC calculated at 8 months post-enrollment. Enrollment of 438 participants will provide 90% power to detect a 5% difference in PDC between the two arms within each nonadherence risk stratum.

Discussion: This trial will evaluate the effect of patient-tailored interventions on specialty medication adherence and will inform how often and why patients are misidentified as nonadherent.

Registration: The trial was deemed a quality improvement initiative by the Vanderbilt University Institutional Review Board. It was registered in ClinicalTrials.gov (NCT03709277) on 17 October 2018.

Conflict of interest statement

Amanda Kibbons, Megan Peter, DeClercq, Leena Choi, Jacob Bell, Jacob Jolly, Elizabeth Cherry, Bassel Alhashemi, Nisha Shah, and Autumn Zuckerman have no conflicts of interest that are directly relevant to the content of this article.

Figures

Fig. 1

Visual summary of the adherence intervention study process. REDCap Research Electronic Data Capture, PDC number of covered days from supply diary/calculated number of days in time period of interest, VUMC Vanderbilt University Medical Center

Fig. 2

Illustration of proportions of days covered (PDC) based on claims data demonstrating an example of a PDC supply diary. Blue bars correspond to the number of days’ supply received at each pharmacy claim. A surplus of medication (shown in red) occurs when a patient fills a prescription before the prior fill is exhausted, and thus the patient has excess supply during the overlapping days. According to the rules for calculating PDC, early refills are shifted forward to begin once the prior fill is exhausted (as shown in fill 4). The study period for all patients is the first 240 days after randomization. The observation window is the time from the date of the first fill to the date of the last fill within the study period and therefore varies by patient. To calculate PDC, the number of covered days is divided by the length of the observation window. In this example, there are 150 covered days in the observation window, and the time from the first to last fill can be calculated as 201 − 11 = 190 days. Thus, the PDC for the given example is 150/190 = 78.9%

Fig. 3

Time periods used in calculations for the study. At enrollment, patients must have filled four or more prescriptions over the preceding 12 months. Proportion of days covered (PDC) will be calculated over two time periods at the time of enrollment: 4 months for eligibility and 8 months for baseline analysis, and once at the end of the 8-month study. Dark blue lines represent inclusion criteria. The green line represents baseline adherence analysis. The yellow line represents the primary outcome analysis