OBJECTIVES: To accommodate the urgent needs of adherence measurement in multiple medication treatments, a macro was constructed to ease the newly proposed approach, the Daily Patient Possession Ratio (DPPR).

METHODS: The prescription refill data (2.5 years) was employed to construct the macro. 19 refill dates (from initial prescription start to last fill end) of 7 different drugs were used in the index calculations. Patient’s medication consuming was investigated daily and weighted by availability. The extra pills from previous prescriptions were carried over to fill the later gap days till used up. The oversupply beyond the follow-up was cut off.

The consumption score between 0 (no medication available) and 1 (all medications available) was assigned for each day and aggregated across all coverage days before finally balanced with the entire follow-up period.

Its face validity was compared with the traditional approach, Medical Procession Ratio (MPR), by leveraging the single medication use to a polypharmacy complex. The impact of medication quantity and methodological stability on adherence was also examined.

RESULTS: The patient volume and variations did not bias the score away.

When the medication quantity increased gradually from 3 to 7, the averaged DPPR rate declined accordingly (95.8%, 87.8%, 85.8%, 84.7% to 81.2%) at a regression rate of 3.22%.

The similar trend at a higher scale was observed in MPR (97.5% for 7 drugs to 85.3% for 3 drugs). They were quite close and highly correlated (Pearson coefficient =0.93, p values < 0.0001). Optimistically DPPR adjusted down the overestimated MRP, the more medications stretched this distance (1.7% at 3 drugs to 4.0% at 7 drugs).

CONCLUSIONS: The presented macro reliably and accurately measured the polypharmacy adherence (DPPR) and liberated the measurement from a complicated, time-consuming, labor-intensive environment. It applies to a wide spectrum of treatment patterns like drugs, regimen or disease levels.