Medication Possession Ratio (MPR) Calculator
Estimate medication possession ratio from dispensed days and period length, with optional overlap correction and adherence target benchmarking.
This tool supports adherence screening and does not replace clinical judgment for therapy effectiveness or safety.
Examples
- Total days supplied 270, period 300 days, overlap 10, target 80% => Medication Possession Ratio: 86.67%. Adjusted supply: 260 days. Target: 80.00%. Gap: +6.67% vs target.
- Total days supplied 150, period 210 days, overlap blank, target blank => Medication Possession Ratio: 71.43%. Adjusted supply: 150 days. Target: 80.00%. Gap: −8.57% vs target.
FAQ
Why does this calculator cap MPR at 100%?
Many quality programs cap adherence ratios at 100% because excess refills do not imply greater-than-perfect adherence behavior.
Should I subtract hospital days?
If inpatient medication exposure is not represented in outpatient pharmacy claims, remove those days from the denominator or document the bias.
What target should I use for chronic therapy?
An 80% threshold is widely used for screening, but disease-specific quality frameworks may require higher thresholds.
Additional Information
- MPR is reported as a percentage and typically capped at 100% for adherence reporting.
- If overlap days are left blank, the calculator assumes 0 overlapping days.
- If target MPR is left blank, the calculator applies a default threshold of 80.00%.