Adherence to Medication Under Mandatory and Voluntary Mail Benefit Designs

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The American Journal of Managed Care, July 2011, Volume 17, Issue 7

Pharmacy benefit designs that mandate mail pharmacy use interfere with prescription drug access, particularly for individuals without previous mail pharmacy experience.


To compare adherence rates under voluntary and mandatory mail benefit designs.

Study Design:

Matched retrospective cohort.


Adherence rates in the first year of therapy were compared between voluntary and mandatory mail cohorts composed of individuals who initiated statin, angiotensin-converting enzyme (ACE) inhibitor, angiotensin receptor blocker (ARB), platelet aggregation inhibitor, metformin, glitazone, or sulfonylurea therapy at a retail pharmacy between January 1 and March 31, 2009. Initiators in mandatory mail plans were matched on therapeutic class, age, sex, prospective risk, and cost of initial prescription with those in voluntary mail plans. Logistic regression models of optimal adherence were constructed to adjust for measured confounders.


Persistence rates were similar through the first 60 days of therapy. The mandatory mail cohort had a notable drop in persistence by day 90 (63.3% vs 56.3%, P <.001), with a more pronounced drop among those without previous mail-service pharmacy use (50.5%). Median medication possession ratio (49.2% vs 57.4%) and optimal adherence (33.6% vs 36.1) were also lower. In the multivariable models, mandatory mail participants were less likely to achieve optimal adherence overall (odds ratio [OR] 0.70; 95% confidence interval [CI] 0.67-0.74) and in the metformin (OR 0.55), sulfonylurea (OR 0.72), ACE inhibitor (OR 0.74), ARB (OR 0.69), and statin (OR 0.69) classes. Participants with no prior use of mail-service pharmacy had significantly lower odds of achieving optimal adherence in all therapeutic classes.


Mandatory mail appears to cause some members to discontinue therapy prematurely, particularly those without previous mailservice pharmacy experience.

(Am J Manag Care. 2011;17(7):e260-e269)

Pharmacy benefit designs that mandate mail pharmacy use interfere with prescription drug access that could be particularly important for individuals with chronic conditions.

  • By restricting pharmacy choice and access, mandatory mail appears to cause some members to discontinue therapy prematurely.

  • When members choose to discontinue rather than switch pharmacy channels, the unintended consequence is a reduction in medication adherence and the potential for increased medical expenses.

  • Individuals without previous use of mail-service pharmacy are particularly sensitive to this plan design and are an important population to target for interventions to support adherence.

A critical challenge in designing pharmacy benefits is to find the optimal balance between access to essential medications and cost management.1 Employers seek pharmacy benefit designs that maximize access to effective medications and support appropriate adherence to those medications, with the intent of reducing health service use and promoting health and productivity. However, as pharmacy expenditures have risen, cost management has received increased attention. In addition to escalating use of incentivized formularies and higher copayments,2 employers increasingly offer a mailservice option as a mechanism to reduce costs. In 2010, nearly 96% of all employers offered mail pharmacy services to their employees.3

The majority of plan sponsors offer “voluntary mail”: a pharmacy benefit that allows prescriptions to be dispensed from either retail or mail-service pharmacy but that discounts out-of-pocket costs to encourage mail-service pharmacy use. In contrast, nearly 19% of employers implement “mandatory mail,” a design that requires use of mail-service pharmacy for maintenance medications by ending benefit coverage for retail-dispensed prescriptions after a predetermined limit is reached. By requiring mail-service pharmacy use for all chronic medications, plan sponsors can expect additional cost savings,4 but they limit access to retail pharmacies, a channel through which the vast majority of prescriptions are dispensed.5

Little is known about how voluntary and mandatory mail benefit designs affect adherence to essential medications. Plan sponsors should be aware of the trade-offs in adherence that may be related to limiting pharmacy choice or other barriers to drug access imposed by mandating a specific pharmacy channel. This trade-off can be analogous to the choice that payers must make when assigning copayments to medications: cost savings through elevated copayments can come at the expense of nonadherence to essential medications.6 Accordingly, we compared voluntary and mandatory mail pharmacy benefit designs with respect to their impact on medication adherence. Payers can use this information to appropriately balance cost management with beneficiary medication adherence when designing pharmacy benefits.


We conducted a matched retrospective cohort study of medication adherence among initiators in their first year of therapy. The sampling frame was employersponsored pharmacy insurance plans that offered either mandatory (n = 85) or voluntary (n = 240) mail pharmacy benefits managed by CVS Caremark between July 1, 2008, and March 31, 2010. Within this sampling frame, we identified potential study subjects among members who were enrolled in a pharmacy insurance plan with a mandatory mail benefit (mandatory mail participants) or a plan with a voluntary mail benefit (voluntary mail participants). In addition, eligible study participants met the following criteria: (1) valid demographics (age, sex, zip code); (2) valid Pharmacy Risk Group score; (3) a paid retail 30-day pharmacy claim (index prescription) between January 1 and March 31, 2009, for a prescription drug in 1 of the following therapeutic classes: HMG CoA reductase inhibitors (statins), angiotensin receptor blockers (ARBs), angiotensin-converting enzyme (ACE) inhibitors, platelet aggregation inhibitors (PAIs), sulfonylureas, metformin, or glitazones; (4) no previous paid pharmacy claim for a drug in the same class within the previous 6 months; and (5) continuous eligibility for pharmacy benefits for the 6 months before and 12 months subsequent to the index prescription.

Mandatory mail participants who met these qualifications were individually matched (1:1 match without replacement) to voluntary mail participants on the following criteria: age (±5 years); sex; index therapeutic class; out-of-pocket cost for the index prescription (±$0.20 per day of supply); and Pharmacy Risk Group category. Therapeutic class definitions were derived from Medi-Span’s Generic Product Identifier. The Pharmacy Risk Group score uses a proprietary algorithm based on pharmacy claims to provide an estimate of each individual’s predicted healthcare costs; this score can be used to adjust for risk in the absence of medical utilization data. The Pharmacy Risk Group score was derived from claims filled prior to the index prescription date. The final analytical sample was limited to the mandatory and voluntary mail participants successfully matched.


Medication adherence was measured for each therapeutic class separately using the following metrics: medication possession ratio (MPR) and persistence. The MPR was defined as the total days of supply divided by 365 days (the follow-up period), and an MPR greater than or equal to 80% signified optimal adherence. Beginning with the index prescription, we catalogued each prescription filled during the follow-up period and aligned them chronologically. Using the days of supply associated with each prescription, we determined the expected availability of drug therapy on a given day. For example, if the index prescription had a 30-day supply and the refill was dispensed on the 32nd day after the index fill date, day 31 would be designated as a day without available drug therapy. Days with available drug therapy were deemed as persistent days, and we calculated the proportion of patients persistent on each day during the follow-up period. Daily persistence was then graphed in 5-day increments and stratified by baseline mail pharmacy use. For all calculations, days of supply from early refills were counted from the beginning of the date of exhaustion of the previous prescription, and the days of supply that extended beyond the follow-up period were truncated.

We constructed multivariate logistic regression models to estimate odds of achieving optimal adherence. Variables used in the matching process were included in the multivariable analysis to provide adjusted estimates for the other variables. The following predictors were included in the models: age (in years, as of the index date; <50, 50 to <58, 58 to <65, and 65 ); sex; geographic region; out-of-pocket costs per day of supply of therapy from the index prescription (categorized by quartile); median household income based on zip code of residence (categorized by quartile); previous mail use (yes/no for a mail prescription in the 6-month period prior to their index prescription); and pharmacy benefit design (mandatory mail vs voluntary mail).


Table 1

Of the 1,238,194 potential study participants, approximately 7% were excluded because of missing or incomplete data, and 34% were excluded because of insufficient eligibility for pharmacy benefits (). Of those who were eligible for pharmacy benefits and who had valid data, nearly 81% were excluded because they had a previous paid pharmacy claim(s) for a drug in the index class and thus were not therapy initiators. Of the remaining participants, approximately half were ineligible because their index prescription was not for a 30-day supply dispensed at a retail pharmacy, though this proportion varied substantially between the 2 cohorts. From the remaining qualified participant pool, 95% of the mandatory mail initiators were successfully matched to voluntary mail participants.

Table 2

The final study cohorts included 27,828 (13,914 mandatory and 13,914 voluntary mail) participants. presents the comparison of demographic (eg, age, sex, region, etc) and utilization (eg, Pharmacy Risk Group, previous mail use) measures overall and by therapeutic class. The cohorts had similar distributions for the matched characteristics and were similar with regard to household income and geographic region of residence. As expected, the mandatory mail cohort had significantly more previous mail pharmacy use.

Across all therapeutic classes, the voluntary mail cohort achieved higher MPR and optimal (MPR >80%) adherence rates than the mandatory mail cohort during the first year of therapy (Table 2). In the voluntary mail cohort, 36.1% achieved and maintained optimal adherence compared with only 33.6% of those in the mandatory mail cohort, resulting in significantly different median MPR scores (57.4% vs 49.2%; P <.001). These results varied by therapeutic class, however. Among participants initiating antidiabetic therapy, voluntary mail participants had higher adherence than mandatory mail participants for the metformin and sulfonylurea classes, but lower adherence for glitazones. Among participants initiating cardiovascular therapy, voluntary mail participants had higher adherence than mandatory mail participants for the ACE inhibitor, ARB, and statin classes, but lower adherence for PAIs (though adherence in general for this class was substantially greater).

Figure 1

Across all therapeutic classes combined, persistence was similar through the first 60 days (). By the 90th day after initiating therapy, the mandatory mail cohort had a substantial drop in the percentage of members who remained on therapy (63.3% vs 56.3%; P <.001), a difference that continued through to day 365 (51.6% vs 46.4%; P <.001). By therapeutic class, these persistence differences were similar to the MPR scores, with voluntary mail participants having higher adherence than mandatory mail participants for sulfonylureas, ACE inhibitors, statins, ARBs, and metformin but lower adherence for glitazones and PAIs (data not shown).

Figure 2

When stratified by previous mail use, the voluntary mail participants exhibited similar persistence during the first year of therapy regardless of previous mail-service pharmacy use (). However, mandatory mail participants without previous mail use had significantly lower persistence than mandatory mail participants with previous mail use. By the 90th day, previous mail users had a persistence rate that was 12 percentage points higher than the rate for those with no previous mail use (62.5% vs 50.5%) and this difference expanded to more than 15% by day 365 (55.4% vs 39.8%).

Table 3

In the multivariable models () increasing age, male sex, higher income, and lower out-of-pocket costs were typically associated with increased odds of achieving optimal adherence. Absence of previous mail use was a significant predictor of adherence overall (adjusted odds ratio [OR] 0.51, 95% confidence interval [CI] 0.48-0.54) and was significant in each therapeutic class, with adjusted ORs ranging from a low of 0.36 (ARBs) to a high of 0.65 (ACE inhibitors). After adjusting for previous mail use, voluntary mail was associated with significantly higher adherence than mandatory mail both overall (adjusted OR 0.70; 95% CI 0.67-0.74) and in 5 of the 7 classes: metformin (adjusted OR 0.55; 95% CI 0.46-0.64), sulfonylureas (adjusted OR 0.72; 95% CI 0.57-0.91), ACE inhibitors (adjusted OR 0.74; 95% CI 0.66-0.82), ARBs (adjusted OR 0.69; 95% CI 0.59-0.81), and statins (adjusted OR 0.69; 95% CI 0.63-0.76). Results for glitazones and PAIs did not reach statistical significance.


Participants with a mandatory mail pharmacy benefit design were less likely to remain persistent during the first year of therapy. Most impacted were those who had no previous mail use and thus were most likely to have been unfamiliar with the requirements of mandatory mail. As expected, both cohorts had a substantial and comparable drop-off in adherence after the first prescription (between days 30 and 60). However, the lower persistence in the mandatory mail cohort beginning between days 60 and 90 indicates potential barriers to access during the period of time when the prescription must be transferred from a retail pharmacy to a mail-service pharmacy. The substantial drop in adherence occurring at this transition point suggests an important target for improved processes at mail-service and retail pharmacies to facilitate transitions between distribution channels—a transition that can require several steps.

Once the benefit design requires use of mail-service pharmacy, subsequent prescription refills submitted by a retail pharmacy for payment are rejected. Thus, for those unaware of the mandatory mail requirement, this process may begin with the unpleasant surprise of a failed attempt to refill the prescription at a retail pharmacy. Yet even in the absence of that, the mandatory mail benefit design requires the member to complete several procedural steps to transfer a prescription. Typically, a consumer requests a new prescription from their provider (eg, for a 90-day-supply prescription with 3 refills allowed, rather than a 30-day supply prescription with 11 refills), contacts the mail-service pharmacy to verify or provide insurance information, obtains necessary forms, and then submits the documentation and prescription to the mail-service pharmacy. Finally, the 90-day-supply prescription often ren quires an additional copayment—often the equivalent of at least two 30-day-supply copayments.

At first glance, lower medication adherence rates among individuals who initiate therapy under a mandatory mail benefit design may appear to contradict recent studies that suggest improved adherence among mail-service pharmacy users.7,8 This apparent contradiction is likely due to the fact that studies of mail-service pharmacy users are enriched with adherent participants (individuals who have been persistent with therapy for years prior to the study period); include individuals who voluntarily elect mail-service pharmacy; and by definition are limited to participants who successfully transitioned to mail-service pharmacy. Because of these substantial differences, it is difficult to compare adherence rates directly.

Nonetheless, the higher adherence among mail-pharmacy users in these studies indicates the importance of supporting access to mail-service pharmacy or, perhaps more importantly, access to the convenience of 90-day-supply prescriptions. A 2010 Pharmacy Benefits Management Inn stitute report documented that employers are increasingly allowing retail pharmacies to dispense maintenance supplies of medications.3 These facts, in combination with the recent growth of 90-day retail pharmacy programs,9,10 highlight the importance of implementing pharmacy benefit designs that preserve access to mail and retail pharmacies while allowing the convenience of 90-day-supply prescriptions via either channel.

That mandating mail pharmacy use presents a barrier to access for some patients is consistent with several lines of evidence, including consumer surveys documenting the importance of pharmacy options,11 comparability of mail and retail pharmacy satisfaction results,12 revealed pharmacy preferences among mandatory mail users,13 and the impact of pharmacy benefit design restrictions on adherence.6,14

A 2001 study of benefit design options indicated that dissatisfaction with pharmacy benefits is primarily due to restricted access.11 Moreover, a 2003 survey sponsored by the National Association of Chain Drug Stores reported that 72% of patients opposed a mandatory mail benefit primarily on the grounds that the design limits personal choice. Yet 48% of these respondents agreed that mail was more convenient than retail.15 These stated preferences are supported by a recent study of revealed pharmacy choice among former mandatory mail plan participants whose benefit design expanded to allow retail pharmacy use again. In this study, nearly 68% of participants initiating maintenance pharmacotherapy selected retail pharmacy if they had not recently used mail service, while only 37% selected retail if they had used mail service for a recent prescription.13

Consumers consistently report high levels of satisfaction with both retail and mail-service pharmacy.12 Yet lower copayments only increase the voluntary selection of mail pharmacy moderately (and in proportion to the discount), while mandatory mail dramatically increases mail pharmacy selection.16 Because financial incentives alone fail to motivate the majority of consumers to transfer maintenance medications from retail to mail pharmacy,17 many consumers elect to pay higher out-of-pocket costs for prescriptions in order to receive them at their community pharmacy: a strong indicator that nonfinancial drivers of utilization also matter to consumers.

Several facts support the relevance, generalizability, and validity of these results. Most importantly, we conducted the study among a random sample of participants covered by pharmacy benefits administered by one of the largest providers of pharmacy benefits management services in the United States. Second, mail pharmacy use continues to grow in popularity, with an estimated 238 million prescriptions dispensed by mail in 2009.5 Further, nearly 97% of employers offer a mail pharmacy option and 17% offer mandatory mail.3 Third, several well-documented factors that influence adherence and could have confounded our results, including sex, age, and out-ofpocket costs, were accounted for and had impacts consistent with those in previous studies of adherence.14,18

Still, there remain unmeasured sources of potential confounding that could have affected our interpretation of benefit design and medication adherence. As neither payers nor members were randomly assigned to pharmacy benefit design, unmeasured characteristics that predict therapy discontinuation and that varied between the mandatory and voluntary mail cohorts could have confounded this relationship. Indeed, it is likely that mandatory mail is, in general, more restrictive than voluntary mail; however, most restrictions (eg, coinsurance, front-end deductibles, formulary tiers) act to increase the copayment, a variable we used to match participants. Second, we analyzed paid administrative claims, which record a pharmacy transaction when a consumer uses pharmacy insurance to cover part of the drug cost. Thus, these data do not include cash purchases of prescriptions. Third, our results should not be considered as definitively causal. In the absence of self-reported reasons for therapy discontinuation, we are left to speculate about the actual causes. Future survey research should focus on the consumer experience during benefit design—mandated transitions in therapy.


Pharmacy benefit designs dictate pharmacy access, drug cost, and formulary coverage and thus are an important public health tool with the potential to improve population health.19 Offering a mail-service pharmacy option is an important benefit design tool that helps to control pharmacy costs and may facilitate medication adherence among those who successfully transition to 90-day-supply prescriptions. However, restricting pharmacy choice by requiring the transfer of prescriptions from retail to mail-service pharmacy causes some members to discontinue therapy early. When members choose to eschew therapy rather than switch to a lower cost alternative, the unintended consequence is a reduction in medication adherence and the potential for increased medical expenses.19,20

Author Affiliations: From Center for Health Research (JLN), Geisinger Health System, Danville, PA; Strategic Research (DSH), CVS Caremark, Scottsdale, AZ; CVS Caremark (TAB), Woonsocket, RI; Brigham & Women’s Hospital (WHS), Boston, MA; Harvard Medical School (WHS), Boston, MA; and Enterprise Analytics, Silverlink Communications (JS) Burlington, MA.

Funding Source: Funding for the research and manuscript was provided by CVS Caremark.

Author Disclosures: Dr Liberman reports being a former employee of CVS Caremark, which offered both mandatory and voluntary mail benefits. He also reports holding stock in the company. He is now with Geisinger Health System. Dr Shrank reports having served as a paid consultant for United Healthcare. He also reports receiving and pending grants from CVS Caremark. Ms Slezak reports previous employment with CVS Caremark. She is now with Enterprise Analytics, Silverlink Communications.

Authorship Information: Concept and design (JLN, DSH, WHS, JS, TAB); acquisition of data (JLN, DSH); analysis and interpretation of data (JLN, DSH, WHS, TAB); drafting of the manuscript (JLN, DSH, JS, TAB); critical revision of the manuscript for important intellectual content (JLN, DSH, WHS, JS, TAB); statistical analysis (JLN, DSH); provision of study materials or patients (DSH); obtaining funding (JLN); administrative, technical, or logistic support (DSH, WHS, TAB); and supervision (WHS, JS, TAB).

Address correspondence to: Joshua N. Liberman, PhD, Geisinger Health System, Center for Health Research, 100 N Academy Ave, MC 44-00, Danville, PA 17822. E-mail:

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