Geisinger Health System’s $0 co-pay drug program for its chronically ill employee population is associated with positive cost savings and a 5-year return-on-investment of approximately 1.8.
Daniel D. Maeng, PhD; James M. Pitcavage, MSPH; Susan R. Snyder, PhD; and Duane E. Davis, MD
The rising cost of healthcare has forced employers, payers, and policy makers to seek innovative ways to meet this challenge. Consequently, the concept of value-based insurance design (VBID) has gained popularity. VBID is generally characterized by the reduction of financial barriers to the purchase of services that provide “high value,” such as use of lower-cost medications and preventive screenings. In theory, the investment of providing such high-value benefits would be more than offset by the avoidance of more expensive medical events.1
To the extent that consumer cost sharing limits access to the high-value care,2,3
this is a plausible hypothesis.
To date, VBID—in the context of prescription drugs—has demonstrated improved medication adherence and certain health-related outcomes, but no obvious cost savings.4-7
In this study, we examined a version of VBID designed by Geisinger Health System (GHS), in collaboration with Geisinger Health Plan (GHP), implemented as a part of its overall employee health and wellness program called MyHealth Rewards (MHR). The evaluation of MHR as a composite intervention has been published previously.8
In our study, we focused on the VBID component of MHR that has eliminated co-payments of select prescription drugs for eligible GHS employees.
MHR includes the following key features: 1) health risk assessment—a Web-based questionnaire to identify opportunities for self-improvements; 2) disease and case management—employees with a confirmed diagnosis of selected chronic conditions are eligible to participate in disease management programs with nurses hired and supervised by GHP. Those experiencing more serious conditions are assigned to GHP’s case management programs, which provide more intensive care management services; 3) financial incentives; and 4) $0 co-pay medications—GHS employees participating in MHR with the eligible chronic conditions may choose to receive $0 co-pay medications from a list of approximately 200 drugs designated for high blood pressure, cholesterol, and diabetes management after meeting the annual deductible of $50 per member. The number of drugs eligible for the $0 co-pay program has increased over time: in 2007, there were 133 such drugs for hypertension, 25 for cholesterol, and 42 for diabetes. By 2011, there were 142, 26, and 45, respectively (see eAppendix 1
[eAppendices available at www.ajmc.com
] for the complete list of eligible drugs).
MHR participation is strictly voluntary. All GHS employees covered by GHP are eligible to participate in the health-risk assessment program; however, only those with the select chronic conditions are eligible to participate in the $0 co-pay program, the disease management programs, and the financial incentives. Note, however, the nurse-based disease and case management programs are not unique to MHR; GHP uses these programs across all its membership, not just for the MHR participants. What is unique, is the fact that these programs are used in conjunction with other MHR program components. MHR is available to all GHS employees and their dependents as long as the employees maintain their health plan coverage through GHP.
We hypothesized that the introduction of the $0 co-pay drug program increased patient adherence to medication therapies, which, in turn, led to reductions in exacerbations and use of acute care, such as hospitalization and emergency department (ED) visits. Thus, we tested the hypothesis that during the months when GHS employees were taking 1 or more of the drugs eligible for $0 co-pay, their total cost of care was lower compared with those months when non-GHS–employees were taking drugs from the same list of drugs eligible for the $0 co-pay program (ie, the drugs that would have qualified for $0 co-pay had these comparison employees been GHS employees at that time).Data
The data were obtained from GHP commercial claims data from 2005 through 2011, which include 2-year pre-intervention data (2005 and 2006), along with 5-year postintervention follow-up data. The intervention group was defined as those GHP members who were employees of GHS throughout the study period (ie, in both the pre- and postintervention periods). The control group was therefore defined as those GHP members who were not employees of GHS throughout the study period. More specifically, the following criteria were applied:
Inclusion criteria: 1) continuous GHP membership from January 1, 2005, through December 31, 2011, and 2) GHP commercial population aged 18 to 64 years.
Exclusion criteria: 1) switched employment between GHS and non-GHS employers at any point during the study period (this ensures that selection of the GHS-employee cohort is not correlated with the implementation of MHR), 2) had a non-GHS primary care provider at any point during the study period (this reduces variation in provider practice styles and referral patterns that may confound the comparison), and 3) did not use any drugs eligible for the $0 co-pay program at any point during the study period (this increases the likelihood that the GHS and non-GHS cohorts are as close to each other as possible in terms of the presence of the relevant chronic conditions by effectively removing the population for whom the $0 co-pay program was never intended).
After applying these inclusion and exclusion criteria, 2251 GHS employees in the intervention group, and 3857 non-GHS employees in the comparison group, were included in the final analytic sample.
First, we used a propensity score-matching method to stratify the sample into 7 mutually exclusive strata based on the following set of baseline (ie, pre-2007) characteristics: 2-year mean per-member-per-month (PMPM) total cost of care, age, and gender. Second, we estimated 2 generalized linear regression models with log-link function and gamma distribution: one for the prescription drug cost and the other for the medical cost measured on a PMPM basis. Cost of care was defined as the “allowed amount”—the sum of GHP’s direct payment to providers and the members’ out-of-pocket costs in terms of co-pays, deductibles, and coinsurance. Note, for the prescription drug costs for the GHS employees, their drug-allowed amounts reflected the $0 co-pay if they were eligible and had participated in the program.
The main explanatory variables were the GHS-employee binary indicator variable, and the binary indicator variable that equals 1 if the member in each month received any drug that appeared in the list of those eligible for the $0 co-pay program in a given month (as determined by the fill date in his or her pharmacy claims data) and 0 otherwise. Note that a value of 1 in the $0 co-pay drug indicator variable does not indicate that the member actually paid $0 co-pay for that drug; rather, it indicates that the member had received 1 or more of the drugs that would have been eligible for the $0 if the member had participated in the $0 co-pay program. Also, the variable does not take into consideration the days’ supply information. That is, if a member had filled a 90-day supply, as opposed to a 30-day supply, it is not assumed that the member had continued to take the drug for the 2 months following the month of the fill because it is not possible to ascertain from the data whether the member had actually done so. This is likely to underestimate the $0 co-pay drug impact and, therefore, may lead to more conservative estimates of the impact.
The key explanatory variable, therefore, is the interaction term between the GHS-employee variable and the $0 co-pay–eligible drug indicator variable. This interaction effect captures any additional differences in cost of care between the GHS and non-GHS employees, above and beyond their baseline differences, and the general impact of receiving $0 co-pay–eligible drugs observed in both groups. A negative coefficient in the interaction term will imply that the $0 co-pay program was associated with a behavior change among the GHS employees in relation to how they use and interact with those $0 co-pay–eligible drugs (ie, GHS employees, for instance, might have been not only more likely to fill their prescriptions for the $0 co-pay–eligible drugs, but also less likely to skip or delay daily dose once the drugs were in their possession).
The effect of the $0 co-pay drug program is confounded by the other components of MHR, as described above. To account for these confounders, the regression models include, as a covariate, an indicator variable for whether the individual was enrolled in MHR in each given month during the study period. This variable captures the composite MHR effect relative to the periods when the members were not enrolled in it. Because the $0 co-pay drug program was a component of MHR, this MHR enrollment variable likely absorbs at least some of the $0 co-pay drug program effect; as such, it may be considered a conservative approach to estimating the program effect.
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