Adherence: PDC, MPR and Gap Days
Proportion of days covered, medication possession ratio and gaps from one drug's fills.
Open the tool → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Fills, one per line
- 2026-01-05, 30 2026-02-01, 30 2026-03-15, 30 2026-04-10, 90
- Period end
- 2026-06-30
- List gaps longer than this many days
- 5 days
Result: PDC 94.9% (168 of 177 days covered), at or above the 80% the Part D adherence measures use; MPR 97.2%.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Fills, one per line: fill date (YYYY-MM-DD), days supply
- Period start (YYYY-MM-DD; blank for the first fill)
- Period end (YYYY-MM-DD; blank for December 31)
- List gaps longer than this many days
How this is calculated
Citation
CMS 2026 Star Ratings Technical Notes, Attachment L: PDC = days covered by at least one fill over the days in the period, with overlapping fills of the same ingredient shifted forward; the Part D adherence measures use a PDC of 80% or more. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.