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Value-Based Insurance Design and Medication Adherence: Opportunities and Challenges
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Value-Based Insurance Design and Medication Adherence: Opportunities and Challenges

Kevin A. Look, PharmD, PhD
Improving the quality of studies evaluating the impact of value-based insurance design programs on medication adherence will serve to better inform healthcare system change.
To evaluate the quality of existing value-based insurance design (V-BID) program evaluations on medication adherence, and to identify areas of expansion for future V-BID policy research.

Study Design
Literature review.

A structured search of the peer-reviewed literature was performed using healthcare and economic databases for studies evaluating the impact of V-BID programs on medication adherence. Characteristics of V-BID programs that may result in biased estimates for V-BID effectiveness were assessed and evaluated.

A total of 20 studies assessing the effects of 17 V-BID programs were identified. Medication adherence generally improved after V-BID implementation (mean effect size 3.4% after 1 year). The V-BID evaluation literature suffers from several methodological issues, such as a lack of reporting on baseline and final adherence rates, or absolute adherence changes. Factors that may influence observed effect sizes include program characteristics, baseline adherence rates, disease category, and disease management programs. Effect sizes were much higher in studies where the primary author reported employment by the study firm or sponsor.

Many of the studies evaluating V-BID programs suffered from a lack of clarity when describing the methods used, or a lack of transparency when reporting results, and much of the evidence comes from studies where potential conflicts of interest exist. Authors should ensure that baseline and/or final adherence values are reported in addition to effect sizes, consistent terminology is used throughout a study, results are assessed for potential bias due to confounding factors, and due diligence has been performed to eliminate alternative explanations.

Am J Manag Care. 2015;21(1):e78-e90
Many studies evaluating value-based insurance design (V-BID) programs suffer from a lack of clarity when describing the methods used or when reporting results, and much of the evidence comes from studies in which potential conflicts of interest exist.
  • Authors should ensure that baseline and/or final adherence values are reported in addition to effect sizes, consistent terminology is used throughout a study, results are assessed for potential bias due to confounding factors, and due diligence has been performed to eliminate alternative explanations.
  • Improving the quality and expanding the scope of the V-BID evidence base will serve to better inform healthcare system change.
Medication adherence represents a major public health concern in the United States, as poor adherence can result in increased morbidity, mortality, hospitalizations, and healthcare costs—especially among patients with chronic diseases.1-5 Due to rising healthcare costs, patients have experienced an increasingly larger burden of their medication costs, which is associated with nonadherence to prescribed medications.3,6-10 Value-based insurance design (V-BID) attempts to maximize healthcare quality and efficiency by reducing patient out-of-pocket costs for high-value treatments in order to increase medication adherence and reduce overall healthcare costs.11-14 A systematic review evaluating the effects of V-BID programs concluded that these programs were consistently associated with improved adherence and lower out-of-pocket spending for drugs, although significant changes in overall medical spending were not observed.15

Despite the rapidly growing literature evaluating V-BID programs, concerns have been expressed about the quality of the empirical evidence supporting V-BID.16-20 A 2011 review of V-BID evidence outlined several weaknesses of the studies available at the time, and a 2013 systematic review provided an overview of V-BID effect sizes and the impact on health expenditures.15,18 However, the number of studies evaluating V-BID programs has nearly doubled since this last systematic review was performed. Additionally, recent studies have focused on the relationship between co-payment reductions and medication adherence, the cost neutrality of V-BID programs, and the adoption of V-BID policies, with minimal discussion of study quality. The current review was undertaken to evaluate the quality of existing V-BID program evaluations on medication adherence and to identify areas of expansion for future V-BID policy research.


An extensive review was conducted to identify published studies that reported adherence outcomes as a result of a V-BID approach to financing prescription drug coverage. A structured search of peer-reviewed journals was performed using PubMed, International Pharmaceutical Abstracts, EconLit, and the National Bureau of Economic Research for studies published or in press before May 2014, using the following search terms: “value based insurance design,” “VBID,” and “benefit based copay.” The inclusion criteria for articles in this review were: 1) published in English, 2) availability of abstract and full-text publications in the databases, 3) use of a value-based insurance design approach for prescription drug coverage, and 4) reported outcome of medication adherence. Literature reviews, commentaries, and meeting extracts were excluded.

Preliminary selection of articles was made according to title and abstract, with final selection based on the manual review of full-text publications. References listed in articles that met the inclusion criteria were assessed, and if relevant, were retrieved and reviewed. Specific information extracted from the selected articles included V-BID implementation year, study population, study firm or sponsor, presence of a disease management (DM) program, sample sizes, targeted drug classes, length of study period, adherence measure used, baseline adherence rates, and adherence effect sizes. Particular attention was paid to whether the evaluation studies contained abnormally low baseline adherence rates, characteristics of included DM programs, or potential conflicts of interest, as these factors may result in biased or misleading estimates for V-BID effectiveness.

An effect size was determined for each therapeutic or drug class (eg, diuretics, beta-blockers) or drug group (eg, oral antidiabetics vs insulin) within each study. The effect size was defined as the adherence change in the treatment group minus the adherence change in the control group (if applicable). An effect size was calculated by the author for studies that did not use this definition or did not report one.


Of the 390 nonduplicate articles identified by the search, a total of 20 studies were selected that evaluated the effects of V-BID programs (Figure).10,21-39 One study evaluated 2 separate V-BID programs,21 while 4 studies were additional analyses of programs that had previously been evaluated and published,29,31,34,35 for a total of 17 unique V-BID programs (Table 1).

V-BID Program Characteristics

Just over half (12) of the published evaluation studies were of V-BID programs implemented by 1 large employer group, with the remainder evaluating programs offered to multiple employer groups (Table 1). To date, only 1 randomized controlled trial has been performed,10 and 1 study each has been performed in a managed care setting,27 a preferred provider organization (PPO),36 and solely among small employer groups (≤50 employees).37 Five studies were of V-BID programs administered by Blue Cross Blue Shield, although 3 were analyses of the same program.33-35,37-38

Disease Management Programs

In total, 10 of the 17 unique V-BID programs included some type of mandatory or voluntary DM program in addition to co-payment reductions (Table 1). Four of these programs were implemented separately prior to the V-BID program,23,24,33-36 and 6 were implemented at the same time as the program or required beneficiary enrollment as a condition for V-BID eligibility.21,25,28-32,38 Member participation was mandatory for all but 1 of the newly implemented DM programs; participation was not mandatory in any of the DM programs implemented prior to V-BID implementation. The DM programs described in the literature varied extensively, including components such as educational mailings, nurse case management, and beneficiary requirements (eg, the completion of labs, health and wellness screenings, or questionnaires).

Sample Sizes

Intervention and control group sample sizes had great variability, ranging from 71 to 190,889 beneficiaries (Table 2). However, sample size reporting was not clear in several studies.33,34,37 For example, Maciejewski et al reported 747,300 program participants and 652,161 nonparticipants.33 However, the authors stated that the control group consisted of 176 self-funded employers representing 638,091 enrollees, which is less than the number of included nonparticipants. Additionally, actual participant and nonparticipant sample sizes used in the unmatched analysis were less than 10% of the reported sample sizes, and approximately 5% in the propensity score–matched analysis.

Targeted Drug Classes

Adherence has been measured for a limited number of medications in V-BID programs. In the 20 published V-BID evaluation studies, medication adherence has been measured in only 4 main disease categories: antidiabetics (17 studies), antihyperlipidemics (10 studies), antihypertensives (9 studies), and medications to treat asthma (4 studies). The only exception to this categorization is 1 study that included the platelet inhibitor clopidogrel.24

Study Characteristics

All but 3 studies used at least 1 year of baseline adherence data,10,21,26 with 2 studies using more than 1 year of baseline data.25,37 Study follow-up periods ranged from 3 months to 3 years post V-BID implementation—with a 1-year follow-up period being the most common (9 studies). Prescription drug claims were used to calculate medication adherence using the medication possession ratio (MPR; 12 studies) or proportion of days covered (PDC; 7 studies), while 1 study relied on self-reported adherence data.26 All but 2 studies reported adherence by therapeutic class or drug group: 1 study used self-reported cost-related nonadherence to diabetes medications,26 and a second study reported overall adherence for all medications taken by beneficiaries with selected cardiovascular medical conditions.35

Baseline Adherence Reporting and Measurement

Baseline adherence rates could not be accurately determined for nearly half of the studies, and was particularly pronounced in earlier evaluations of V-BID programs (Table 3). These studies either did not report baseline adherence rates, included them only in figures or online appendices, provided 1 rate without specifying which group it applied to (ie, treatment or control), or provided only general adherence ranges.10,22-24,27,28,31,33,34,37 Additionally, many studies only reported effect sizes and did not include final adherence rates or the change in adherence for the treatment and/or control groups.23,24,27,28,30,31,33-35

Baseline adherence measured using MPR or PDC in the treatment groups ranged from 9.7% to 88%. The majority of studies used some type of adjustment or matching technique to minimize baseline differences in participant demographics between the 2 groups; however, the significance of differences in baseline adherence between the treatment and control groups was not assessed in many studies, and statistically significant differences were seen in several studies despite the use of these techniques.21,22,30 Additionally, several studies used different measures for baseline adherence, final adherence, and outcome adherence rates. For example, 3 studies provided unadjusted baseline adherence rates prior to matching, whereas the results were obtained using adjusted analyses after matching.33-35 An additional study reported baseline adherence as the proportion of the study population with an MPR >80%, but reported an outcome of mean change in adherence between the treatment and control groups.22

V-BID Effect Sizes

Table 3 shows the estimated effect size of the V-BID programs on medication adherence after 1, 2, and 3 years. Effect sizes after 1 year ranged from –3% to 22.6%, with a mean improvement of 3.4%. Although decreased adherence after 1 year was seen in 6 of the V-BID programs studied, only 1 of these findings was statistically significant.28 Likewise, the decreases in adherence seen after 2 years (3 studies) and 3 years (1 study) were nonsignificant. Effect sizes generally improved over time, with mean effect sizes of 3.5% and 4% after 2 and 3 years, respectively; however, 2 studies did find slight decreases over time.29,36 The statistical significance of the effect sizes could not be determined for several studies, either because a final effect size was not calculated,38 or because statistical significance was not assessed.28,32

The findings for V-BID programs within DM initiatives were inconsistent, and the mean effect size was identical (3.4%) after 1 year among studies with or without associated DM programs. However, the mean effect size was 2.3% with existing DM programs and 4.2% with newly implemented DM programs; this difference was also seen after 2 years (mean of 2.5% in existing programs, 4.2% in new programs). No studies were found that evaluated a V-BID program without a DM program beyond 1 year, and all studies with 3 years of post implementation data incorporated newly implemented DM programs (mean 4%).

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