Medication days' supply, adherence, wastage, and cost among chronic patients in Medicaid

Background: In an attempt to contain Medicaid pharmacy costs, nearly all states impose dispensing limits on medication days' supply. Although longer days' supply appears to increase the potential for medication wastage, previous studies suggest that it may also decrease pharmacy expenditures by reducing dispensing fees and drug ingredient costs. This study was conducted to determine whether 90-day refills at community pharmacies could improve adherence, minimize wastage, and control costs.

Methods: This retrospective observational study used California Medicaid claims, from the Walgreens pharmacy chain dated January 2010, to identify 52,898 patients prescribed statin, antihypertensive, selective serotonin reuptake inhibitor (SSRI), or oral hypoglycemic medications. Adherence was measured by medication possession ratio (MPR) and persistency with a 30-day gap. Medication wastage was defined as a switch of drug or drug strength within the same therapeutic class that occurred before the expected refill date.

Results: Adherence was 20% higher and persistency was 23% higher for the 90-day group than the 30-day group. This amounted to an average increase of 0.14 MPR and 44 days of continuous therapy. The two groups had comparable proportions of patients with wastage. After subtracting an average wastage cost of $7.34 per person per year (PPPY), all therapeutic classes had PPPY savings: statins ($7.70), antihypertensives ($10.80), SSRIs ($18.52), and oral hypoglycemics ($26.86).

Conclusion: Across four drug categories and compared to 30-day refills, patients with 90-day refills had greater medication adherence, greater persistency, nominal wastage, and greater savings.