Methods of compliance and persistence calculation

1. SHAIST, R.Choi

2. 1. Andrew M et al. A Checklist for Medication Compliance and Persistence Studies Using
Retrospective Databases. Value Health. 2007 Jan-Feb;10(1):3-12
2. Steiner JF, Koepsell TD, Fihn SD, Inui TS. A general method of compliance assessment
using centralized pharmacy records. Description and validation. Med Care 1998;26:814–
23.
3. Farmer KC. Methods for measuring and monitoring medication regimen adherence in
clinical trials and clinical practice. Clin Ther 1999;21:1074–90.
4. Gundula Krack et al. Drugs Real World Outcomes. 2016 Sep; 3(3): 265–278. Claims Data A
nalysis of Tumor Necrosis Factor Inhibitor Treatment Dosing Among Patients with Rheum
atoid Arthritis: A Systematic Review of Methods
5. ELPT: Benner JS, Glynn RJ, Mogun H, et al. Long-term persistence in use of statin therapy
in elderly patients. JAMA 2002;288:455–6.
6. PDC: Li P et al. Adherence, discontinuation, and switching of biologic therapies in medicai
d enrollees with rheumatoid arthritis. Value Health. 2010 Sep-Oct;13(6):805-12

3.  MPR(Medication possession ratio )  “Chronic”
 Days of supply, DOS (e.g., 60 tablets BID  30 days supply)
 MPR(%) =Sum of days of supply(총처방일수)/ T (관찰기간)
 CMG (continuous measure of medication gaps)  “Acute, multiple Rx”
 Sum of the days in the gaps between refills in the observation period is divi
ded by time between the first and last fills
 The percentage of time the patient does not have the medication available f
or use.
 CMG(%)=Number of days of medication supplied within the refill interval/
number of days in refill interval
90 90 90 30 90 120 90 90 30 90
MPR = 540/810 = 66.6%
Andrew M et al. Value Health. 2007 Jan-Feb;10(1):3-12

4.  Persistence adds the dimension of time to the analysis
 The time over which a patient continues to fill a prescription, or the time from the ini
tial filling of the prescription until the patient discontinues refilling a prescription
 ELPT, Estimated level of persistence
 the percentage of individuals remaining on therapy (persistent) at a given time
 ELPT(%)=Proportion of patients refilling each subsequent prescription with (X*days
supplied) from fill n
 Persistence Curve (similar to Kaplan–Meier curve), Early drop out detection
Andrew M et al. Value Health. 2007 Jan-Feb;10(1):3-12

5.  PDC, Proportion of days covered(0-1 or %)
 A measure of patient compliance that has been used with increasing frequency
 the PDC has the advantage of simultaneously reflecting both C&P
Proportion of days covered according to Li et al. for subcutaneous drugs. DOS days of supply
Option
Andrew M et al. Value Health. 2007 Jan-Feb;10(1):3-12
Gundula Krack et al. Drugs Real World Outcomes. 2016 Sep; 3(3): 265–278
“Dosing considered”

6.  Example : PDC
Mean, Median, and Interquartile Range of the Proportion of Days Covered by Statin for Each Interval
Gundula Krack et al. Drugs Real World Outcomes. 2016 Sep; 3(3): 265–278
Li P et al. Value Health. 2010 Sep-Oct;13(6):805-12

7.  Persistent days : number of days to discontinuation and number of
prescription refills over a period of time
 The number of days to discontinuation
▪ a simple count of days from the index prescription to the date of the final
dispensing
▪ Option : inclusion of the days for which the final fill (e.g., final 30 days)
 The number of refills
▪ usually within 12 months of the index fill, could include patients who refill long
after the allowed 30- or 60-day gap for being considered non-persistent.
 “As needed medicine” e.g., treatments for seasonal allergy
90 30 90 30 90 210 90 30 90
Persistent days = 390 days
Gap days = 90 days
Persistent days = days supply + off days
If max off days > gap days(90days), then the patient is not persistent
Index date
off days off days off days
Option
Andrew M et al. Value Health. 2007 Jan-Feb;10(1):3-12