Medication Utilization and Adherence in a Health Savings Account-Eligible Plan
Published Online: December 18, 2013
Paul Fronstin, PhD; Martin-J. Sepulveda, MD; and M. Christopher Roebuck, PhD, MBA
Medication is important in the management of noncommunicable chronic diseases, which affect nearly one-half of adults and cause approximately 70% of deaths in the United States.1 Prescription drugs accounted for 12% of healthcare spending in 2012, more than double the level of 30 years ago (5%).2 In general, this shift toward greater use of pharmacotherapy has provided net societal benefits.3 For example, medical cost offsets in Medicare A and B have been documented as a result of adding drug coverage under Medicare Part D.4 Prior work has found that medication adherence produced substantial savings as a result of reductions in hospitalization and emergency department use, and it is thus a matter of great importance to policy makers, insurance plan sponsors, physicians, and patients.5
Despite clinical and economic benefits, only about half of patients take medications for their chronic conditions as recommended by their physicians.6 Moreover, as much as one-third of initial prescriptions go unfilled.7,8 For example, studies have found that more than 25% of patients with coronary artery disease discontinued drug therapy within 6 months of initiation,9 and adherence among patients receiving statins fell from nearly 80% within the first 3 months of treatment to only 25% after 5 years.10 Overall, adherence rates across a number of therapeutic classes have been reported at between 28% and 66% after 6 months, and 18% to 54% after 1 year.11 Nonadherence has been estimated to cost the US healthcare system between $100 billion and $289 billion,12 and has spawned new plan designs such as value-based insurance design to address this challenge.13 Public efforts to raise awareness of the adverse effects of nonadherence have also been initiated, such as the “Script Your Future” campaign of the National Consumers League.14
Medication adherence is known to be affected by out-of-pocket cost to patients.6 For this reason, it is important to understand medication adherence in populations enrolled in relatively new types of health plans that combine potentially high out-of-pocket costs as a result of high deductibles with tax-preferred savings accounts (consumer-directed health plans; CDHPs). First introduced in 2001 with health reimbursement arrangements (HRAs), savings account–based high-deductible plans were extended by the Medicare Modernization Act of 2003, which authorized high-deductible health plans with health savings accounts (HSAs). Both types of CDHPs have grown steadily over the past decade such that by 2011, 23% of employers had offered either an HRA- or HSA-eligible CDHP—covering about 21 million individuals or about 12% of the privately insured market.15,16 About 13.5 million individuals were in a CDHP with an HSA account by January 2012.17 Importantly, as of 2012, 8% of large employers had completely replaced their healthcare coverage with only a CDHP.18
Much of the existing literature on the impact of CDHPs on use of health services and costs focuses on HRAs. These plans have been in existence longer, and data on HSAs are not as readily available. Moreover, several studies were limited to examining the impact of CDHP on healthcare spending.19-21 Peer-reviewed articles about the impact on prescription drug use of adopting a CDHP have largely concentrated on the number of prescription drug fills, generic and brand use, and mail order use by CDHP enrollees compared ith non-CDHP enrollees.22-27 Sometimes, populations with specific diseases were examined.
We identified only 2 studies that report on the impact of a CDHP on medication adherence. An early study examining 1 year of data after the adoption of an HRA found that 7% of those enrolled in the highest deductible CDHP and taking medication to treat hypertension in late 2003 were no longer persistent with therapy in 2004, though adherence was unchanged among individuals who continued to take medications after moving to the CDHP.28 A more recent study using data from 2005 and 2006 found that after enrolling in a CDHP (both HRAs and HSAs were examined), individuals were less likely to refill prescriptions for cardiac conditions and elevated cholesterol. The CDHP members with asthma, cardiac conditions, and high cholesterol also had reduced medication adherence and persistence with medications.29
Given that CDHPs alter out-of-pocket cost for prescription drugs by subjecting them to the high deductible, one might expect this plan design to impact medication adherence. The magnitude and duration of the effect are unclear, however, because an individual with a CDHP plan may have money in an HRA or HSA, and individuals’ use of these funds will influence out-of-pocket costs for prescription drugs over ime. The account type, employer contribution level, account ownership, and rollover provisions will further complicate the issue.
This study evaluates the impact of adopting an HSA-eligible CDHP (CDHP-HSA) on medication adherence for individuals with chronic disease. Data come from a large manufacturer that replaced all of its existing health insurance options with a CDHP-HSA. Pre-post changes in medication adherence were derived from pharmacy claims and were compared with changes in adherence in a matched control group of a second employer that did not alter its healthcare coverage.
DATA AND METHODS
On January 1, 2007, a large Midwestern manufacturer fully replaced its existing preferred provider organization (PPO) health insurance plans with CDHP plans with an HSA. All active employees and their dependents were transitioned to the new plan and were given a choice between 2 annual deductible levels: $1250 individual/$2150 family or $2150 individual/$4300 family. The employer contributed the same amount to the HSA regardless of deductible level, though contributions were higher for those with family coverage.
To evaluate the impact of this plan design change on medication utilization and adherence, integrated pharmacy and medical administrative claims data, as well as enrollment information, were used. A control group was constructed, as described below, using data on another larger employer’s workers, who were consistently covered under traditional PPO plans. To be included in the analysis, subjects were required to be continuously eligible for benefits during the 3-year study period (January 1, 2006, through December 31, 2008) and aged at least 18 years as of January 1, 2006, but less than 65 years as of December 31, 2008. Furthermore, individuals must have had 1 or more of 5 chronic conditions: hypertension, dyslipidemia, diabetes, asthma/chronic obstructive pulmonary disease (COPD), and depression. These conditions were chosen because they are highly prevalent, costly, and routinely managed with pharmacotherapy.30 Patients were defined as having a condition if they had at least 1 inpatient or 2 outpatient claims with an International Classification of Diseases, Clinical Modification Ninth Revision diagnosis code for the illness and at least 1 prescription drug fill indicated for the condition in 2006. Table 1 shows the classifications utilized. These inclusion criteria were met by 1023 CDHP-HSA enrollees with hypertension, 1184 with dyslipidemia, 314 with diabetes, 169 with asthma/COPD, and 430 with depression.
A control group was created using data from another larger national employer. We attempted to pair each member of the CDHP group with 1 individual from the comparison pool using coarsened exact matching, a technique that reduces dimensionality through the binning of variables used in the match process.31 Specifically, for each chronic condition, subjects were exactly matched on baseline (2006) values of the following variables with specified cut points (in parentheses): sex; age (25, 35, 45, and 55 years); geographic region; Charlson Comorbidity Index score (0, 1, 2, 3)32,33; proportion of days covered (PDC; 0.2, 0.4, 0.6, 0.8); and an indicator for whether or not the first prescription occurred after April 1, 2006 (ie, a proxy measure for a new user because the patient apparently did not have medication on hand at the beginning of 2006). Using these parameters, matches were obtained for a majority (68%-92%) of study subjects. Final sample sizes for the CDHP and control groups were 937 with hypertension, 1057 with dyslipidemia, 226 with diabetes, 115 with asthma/COPD, and 347 with depression.
Three annual measures of medication utilization and adherence were used as dependent variables: (1) the number of 30-day adjusted prescriptions filled for the condition; (2) the PDC for the condition, which represents the fraction of days in the period that the patient had at least 1 drug for the condition on hand; and 3) a flag indicating a PDC of 0.80 or higher, a commonly used threshold for adherence.5 Proportion of days covered is now used, for example, by the Centers for Medicare & Medicaid Services as a quality measure component of the Star Ratings calculation for stand-alone prescription drug plans, as well as Medicare Advantage Plans.34
PDF is available on the last page.