Calculate proportion of days covered (PDC) from covered days or prescription fill dates and days supplied, and see how many more days reach a target.
Note: PDC is a claims/fill-availability measure, not proof that medication was taken. Do not start, stop, or change medication based on this result. Official measures define the therapeutic category, enrollment and measurement period, exclusions, overlap rules, and threshold. Use one measure-defined medication or therapeutic category per schedule and follow that specification. An 80% target is used by specific PQA/CMS measures but is not universal; this calculator does not label a person adherent or nonadherent.
Proportion of Days Covered Formula
The following two example problems outline the steps and information needed to calculate the Proportion of Days Covered.
Variables:
- PDC (%) is the Proportion of Days Covered
- DC is the number of unique covered days within the chosen period, after the applicable overlap rules
- D is the number of days in that same measurement period; the dated schedule counts both endpoints
Divide unique covered days by days in the same measurement period, then multiply by 100. Do not add overlapping supply twice. The fill-schedule estimate carries early supply forward only when all entered rows share the same target ingredient; its other policy counts the calendar union without stockpiling. Official measure eligibility, exclusions and inpatient or skilled-nursing adjustments are not implemented here.
How to Calculate Proportion of Days Covered?
The following steps outline how to calculate the Proportion of Days Covered.
- First, determine the number of days covered.
- Next, determine the total number of days.
- Next, gather the formula from above: PDC = DC / D * 100.
- Finally, calculate the Proportion of Days Covered.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
number of days covered = 72
total number of days = 90
PDC = DC / D * 100 = ?
