If patients met any of the exclusion criteria for discontinuation, the primary care provider (PCP) was notified to place a consult to the PACT Pharmacy Clinic for individualized interventions and close monitoring. Patients prescribed niacin for nonlipid indications were allowed to continue with their current drug regimen. At each encounter, the PACT CPS assessed for ADRs, made individualized medication changes, and arranged follow-up appointments. Once the interaction was resolved and treatment goals met, the PCP resumed monitoring of the patient’s lipid therapy.
Following all pharmacist interventions, a retrospective quality improvement analysis was conducted. The primary outcome was to evaluate the impact of discontinuing gemfibrozil and niacin by protocol on patients’ laboratory results. The coprimary endpoints were to describe the change in TG levels and the percentage of patients with TGs ≥ 500 mg/dL at least 5 weeks following the pharmacist-directed discontinuation by protocol. Secondary outcomes included the time required to resolve the interactions and a description of the PACT CPS pharmacologic interventions. Additionally, a quality assurance peer review was used to ensure the pharmacists appropriately utilized the protocols.
Data were collected from August 2016 to September 2017 for patients prescribed gemfibrozil and from May 2017 to January 2018 for patients prescribed niacin. The time spent resolving interactions was quantified based on encounter data. Descriptive statistics were used to analyze demographic information and the endpoints associated with each outcome. The project was reviewed by the University of Missouri Institutional Review Board, Truman VA privacy and information security officers, and was determined to meet guidelines for quality improvement.
Results
The original STOP report included 397 drug interactions involving statins with gemfibrozil or niacin (Table 1). The majority of patients were white and male aged 60 to 79 years. Gemfibrozil was the most common drug involved in all interactions (79.8%). The most common statins were atorvastatin (40%) and simvastatin (36.5%).
Gemfibrozil-Statin Interactions
Pharmacists discontinued gemfibrozil by protocol for 94 patients (29.6%), and 107 patients (33.8%) were referred to the PACT Pharmacy Clinic (Figure 3). For the remaining 116 patients (36.6%), the drug interaction was addressed outside of the protocol for the following reasons: the drug interaction was resolved prior to pharmacist review; an interacting prescription was expired and not to be continued; the patient self-discontinued ≥ 1 interacting medications; the patient was deceased; the patient moved; the patient was receiving ≥ 1 interacting medications outside of the VA; or the prescriber resolved the interaction following notification by the pharmacist.
Ultimately, the interaction was resolved for all patients with a gemfibrozil-statin interaction on the STOP report. Following gemfibrozil discontinuation by protocol, 76 patients (80.9%) had TG laboratory results available and were included in the analysis. Sixty-two patients’ (82%) TG levels decreased or increased by < 100 mg/dL (Figure 4), and the TG levels of 1 patient (1.3%) increased above the threshold of 500 mg/dL. The mean (SD) time to the first laboratory result after the pharmacists mailed the notification letter was 6.5 (3.6) months (range, 1-17). The pharmacists spent a mean of 16 minutes per patient resolving each interaction.