The Impact of Automatic Refill Programs on Medication Adherence


Concerns persist that automatic prescription refill programs increase medication oversupply.

Automatic prescription refill programs can help improve patient adherence, especially among patients with chronic diseases, without contributing to medication wastage due to oversupply, the results of a recent study suggest.

Nearly half of American adults are prescribed medication for a chronic disease, but many patients do not adhere to their medication regimens, which contributes to higher healthcare costs. There is, however, strong evidence that adherent patients experience better health outcomes and incur lower healthcare costs than patients who are not adherent.

Another issue of concern is medication oversupply, which contributes to increased regimen complexity, opiate abuse, antibiotic resistance, and environmental toxicity. Medication oversupply leading to wastage can also burden healthcare budgets.

One initiative designed to improve medication adherence is automatic prescription refill programs. In these programs, patients on prescriptions for maintenance medications with multiple refills are provided a simple mechanism to authorize their next refill before the current supply is exhausted. When the prescription is refilled, the pharmacy advises the patient that the prescription is ready for pick-up at the pharmacy.

Medication Adherence and Medication Oversupply

A recent retrospective cohort analysis reported in the American Journal of Managed Care compared 2 outcomes—medication adherence and number of excess days of therapy on hand at the time of prescription pick-up—between a sample of patients enrolled in an automatic refill program (n = 128,310) at CVS pharmacies (refill cohort) and a propensity matched control cohort of patients (n = 126,048) not enrolled in the program.

The first outcome—adherence—was measured using the medication possession ratio (MPR), defined as the number of days of medication dispensed during the year divided by the number of days that the person should have been on therapy.

Adherence Results

Patients in the refill cohort demonstrated significantly greater adherence than those in the control cohort. Refill cohort patients with a 30-day fill had an overall MPR that was 3.0 points higher than that of controls.

MPR Between Refill and Control Cohorts:

Total Across Medication Classes

30-Day Fillers

MPR Refill 83.5%

MPR Control 80.7%

Adjusted Δa 3.0%

90-Day Fillers

MPR Refill 89.8%

MPR Control 88.8%

Adjusted Δb 1.4%

aAdjusted for demographic and clinical confounding factors. Difference in percentage points between the refill and control cohorts; a positive difference indicates that the refill cohort has better adherence than control. All classes significant at P<.001.bAll significant at P<.05, except as noted.Source: CVS Caremark pharmacy claims data from January 1, 2010, to December 31, 2011.

Medication Oversupply Results

The study also reported 2 measures of medication oversupply:

  • The proportion of patients receiving more than 365 days of medication during the exposure period
  • The average days oversupply on hand at the time of prescription pickup during the exposure period.

Comparison of Oversupplya Between Refill and Control Cohorts:

Total Across Medication Classes

30-Day Fillers

Excess Days Refill 3.32

Excess Days Control 5.82

Observed Δb —2.50

90-Day Fillers

Excess Days Refill 7.19

Excess Days Control 9.38

Observed Δb —2.10

aExcess days at time of fill.bNegative difference indicates that the refill cohort received medication later than control. Adjusted P value for the difference is <.001, unless specified otherwise.Source: CVS Caremark pharmacy claims data July 1, 2011, to December 31, 2011; sample limited to members receiving over 365 days of medication during year.


Although oversupply rates were high overall in this study, improved medication adherence was achieved without an increase in medication oversupply, which supports the study’s hypothesis that automatic refill programs help to reduce, not exacerbate, the problem of prescription drug oversupply.

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