The Effect of Zero Copayments on Medication Adherence in a Community Pharmacy Setting

Abstract

Background: Prescription medication copayments can be a financial burden to many patients. When patients cannot afford their medications, they may become nonadherent, and as a result, this can lead to an increase in chronic disease complications and healthcare costs. Objective: The objective of this study was to determine if zero copayments have an effect on medication adherence in a community pharmacy. Methods: This retrospective cohort study examined the prescription refill records of patients who filled specific generic medications for hypertension, hyperlipidemia, and gastroesophageal reflux disease (GERD) in 2016 at the NSU Clinic Pharmacy. The adherence rates of patients with zero copayments were compared to the adherence rates of patients with copayments greater than $0. Adherence was determined by calculating the proportion of days covered (PDC). Patients were considered adherent if their PDC was greater than or equal to 80%. Results: GERD patients with no copayments had average PDC ratios of 87.4% and were statistically significantly more adherent than GERD patients with copayments, who had average PDC ratios of 76.7% (P = 0.042). Hyperlipidemia and hypertension patients with no copayments had average PDC ratios of 89.3% and 90.3%, respectively, and those with copayments had PDC ratios of 85.3% (P = 0.314) and 87.9% (P = 0.534). Conclusion: Overall, patients with $0 copayments had higher adherence rates than patients with copayments greater than $0. GERD patients with no copayments were significantly more adherent than GERD patients with copayments. However, no statistically significant difference was found between patients with or without copayments in the hyperlipidemia and hypertension cohorts. Further studies are recommended to analyze additional factors that may influence medication adherence. INTRODUCTION Prescription medication nonadherence is a major health problem in the United States. Previous research studies have shown that medication nonadherence leads to poor health outcomes and chronic disease state complications, resulting in increased utilization of physician office visits, urgent care and emergency room services, and hospitalizations, as well as increased morbidity and mortality.1-5 It is estimated that medication nonadherence in the United States is responsible for about 10% of hospitalizations and at least 125,000 deaths annually.5 As a result, medication nonadherence leads to an overall increase in healthcare expenditures, costing the healthcare system between $100 billion to $289 billion per year.2-3,5 Medication nonadherence can be attributed to multiple causes, such as patient sociodemographic characteristics, economic factors, patient beliefs and perceptions, cognitive function, medication adverse effects, disease severity, medication regimen complexity, treatment duration, access to care, Corresponding author: Melissa Jimenez, PharmD Nova Southeastern University, NSU Clinic Pharmacy 3200 S. University Dr., Ft. Lauderdale, FL 33328 Email: [email protected] prescription drug coverage, etc.3,5-6 Medication cost is considered one of the most significant barriers to adherence for many patients. Several studies suggest that an inverse relationship exists between prescription drug copayments and medication adherence.1-3,7-10 When patients cannot afford to purchase their medications, they may become nonadherent to their medication regimens by skipping doses, splitting tablets, or stopping their medications altogether. This can lead to poor health outcomes and increased healthcare costs.1-2,7,8,10 Hypertension and hyperlipidemia are among two of the most common chronic medical conditions for which prescriptions are filled in community pharmacies in the United States. Adherence to antihypertensive and antihyperlipidemic medications is critical to the management of these mostly asymptomatic conditions in order to prevent and reduce the risk of future cardiovascular events.11-14 Uncontrolled hypertension can lead to serious cardiovascular complications, such as stroke, heart failure, atrial fibrillation, coronary artery disease, and peripheral vascular disease.11 Likewise, uncontrolled hypercholesterolemia can increase the risk of coronary and cerebrovascular events. Complications from uncontrolled hypertension and hyperlipidemia can ultimately increase the risk of cardiovascularrelated morbidity and mortality.13,15 For example, poor statin use and uncontrolled hypercholesterolemia alone is responsible for Original Research PRACTICE-BASED RESEARCH http://z.umn.edu/INNOVATIONS 2019, Vol. 10, No. 2, Article 16 INNOVATIONS in pharmacy DOI: https://doi.org/10.24926/iip.v10i2.1633 2 nearly 635,000 new coronary events, almost 800,000 strokes, and about one in six deaths annually.15 Gastroesophageal reflux disease (GERD) is another health condition frequently seen in community pharmacies. GERD is mostly a symptomatic condition in which patients usually experience heartburn and acid reflux. Adherence to acidreducing medications is important in the treatment of GERD. However, studies show that treatment failure is high among GERD patients due to medication nonadherence.6,16 Uncontrolled GERD can lead to complications such as esophagitis, esophageal erosions, Barrett’s esophagus, and esophageal adenocarcinoma.6,16-17 GERD is the most expensive gastrointestinal disease in the U.S. and is associated with over $10 billion in direct medical and drug costs.17 Prior research studies suggest that medication adherence can be improved by reducing patient copayments and out-of-pocket costs.1,3,5,18-19 However, there is a limited amount of published research available regarding whether $0 copayments have an impact on medication adherence, particularly in patients with commercial insurance. The objective of this study was to determine if zero copayments had an effect on medication adherence on prescriptions filled in a community pharmacy setting. METHODS Data Source and Study Design This retrospective cohort study was approved by the Institutional Review Board at Nova Southeastern University. The study was conducted at the university’s full-service community pharmacy on campus in Fort Lauderdale, Florida. The pharmacy’s prescription refill records were used to determine the medication adherence rates of patients who filled specific generic medications for hypertension, hyperlipidemia, and GERD. Subjects Adult patients aged ≥ 18 years who filled at least two prescriptions between January 1st, 2016 through December 31st, 2016 for any of the following disease states and medications were included in the study: hypertension (lisinopril, losartan), hyperlipidemia (atorvastatin, simvastatin), and GERD (omeprazole, pantoprazole). Patients less than 18 years of age and patients who became deceased in 2016 during the study period were excluded from the study. For each disease state, patients were categorized into either the treatment group or the control group based on their copayments. The treatment group consisted of patients with zero copayments for their medications, and the control group included patients with copayments greater than $0 for their medications. All patients included in the study had commercial insurance plans. Patient Demographics and Baseline Characteristics Patient demographics and baseline characteristics were compared between zero-copayment and copayment groups for each disease state. The variables analyzed included age, gender, number of concurrent medications, and whether patients were new or continuous patients to therapy. Patients were classified as new patients if they started the study medication during any month in 2016, and patients were considered to be continuous patients if they started the study medication any time before 2016. Adherence For each patient, medication adherence was determined by calculating the Proportion of Days Covered (PDC). PDC is the preferred method of measuring medication adherence for the chronic diseases discussed in this research study and is supported by the Pharmacy Quality Alliance, the Centers of Medicare and Medicaid Services, and the Centers for Disease Control and Prevention.20-21 The following formula was used to calculate PDC: PDC = (Number of Days in Period “Covered” / Number of Days in Period) × 100% The numerator refers to the number of days during the study period in which patients had medication based on pharmacy pick up dates and days’ supply. Meanwhile, the denominator refers to the number of days of the study period for each patient (i.e. 365 days for continuous patients, and the number of days from the index date in which the patient first picked up the medication in 2016 until the end of the year for new patients). Patients were considered to be adherent if their PDC was greater than or equal to 80%, and patients were classified as nonadherent if their PDC was less than 80%. The PDC threshold of 80% or greater is considered to be the goal adherence rate for most chronic disease states in which medications are believed to provide the most clinical benefit to patients.20-21 Statistical Analyses A series of descriptive measures associated with demographic and baseline characteristics were provided as counts, percentage means, and standard deviations. Chi-square tests were used to assess the statistical significance of differences for categorial variables. Differences in medication adherence rates between zero-copayment and copayment populations were compared using t-test. A critical value of 0.05 was set as the threshold for statistical significance. RESULTS There was a total of 320 unique patients that met the inclusion criteria. One patient was excluded from the study due to death during the study period, and one patient was excluded due to having an age less than 18 years of age. It is important to note that about a third of the patients belonged to more than one disease cohort. As shown on Table 1, the hypertension cohort consisted of 151