Presentation is loading. Please wait.

Presentation is loading. Please wait.

Defining Adherence and Persistence Sapna N. Patel UCSF Pharm. D. Candidate 2008 Preceptor Dr. Craig S. Stern March 21, 2008.

Similar presentations

Presentation on theme: "Defining Adherence and Persistence Sapna N. Patel UCSF Pharm. D. Candidate 2008 Preceptor Dr. Craig S. Stern March 21, 2008."— Presentation transcript:

1 Defining Adherence and Persistence Sapna N. Patel UCSF Pharm. D. Candidate 2008 Preceptor Dr. Craig S. Stern March 21, 2008

2 Pictures

3 Relevance Evaluating adherence & persistence is necessary for accurate assessment of: Cost-effectiveness of therapy Quantifying drug exposure in a population over time Drug Utilization Patterns for Formulary Development Identifying appropriate therapy for patients Assessing clinical outcomes of treatment Prior Authorization Criteria

4 Impact of A&P Low adherence & persistence Increased morbidity & mortality Increased health-care costs Forgiveness: therapeutic effects of drug therapy despite noncompliance

5 Proposed Definitions International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Adherence (compliance): the extent to which a patient acts in accordance with the prescribed interval & dose of a dosing regimen Persistence refers to the act of continuing treatment for the prescribed duration Treatment adherence & persistence together contributes to overall drug effectiveness

6 CMS Definitions

7 Current Issues Multiple definitions and measurement models Hinder health outcomes & cost-effectiveness analysis Prevent comparisons of different studies Standardized definition would: Help develop more effective strategies to enhance medication related A&P and decrease health-care costs

8 Measures of Adherence Direct Indirect Desired observation or study evaluation period Between fills periods Treatment Gaps

9 Direct Methods MethodProsCons Directly Observed Therapy Most accurate Time consuming Impractical Hiding pills Medicine or Metabolite Blood Levels Objective Expensive Metabolism variation White coat adherence Biologic Markers in blood Objective Time consuming Expensive

10 Indirect Methods MethodProsCons Questionnaires, self- reporting Cost-effective Time consuming Useful in clinical setting Subjective Infrequent visits = increased error Prescription rate refills Objective Expensive Metabolism variation White coat Adherence Pill Counts Objective Easy-to-do Quantitative results Subjective Easily altered by patient

11 Measuring Adherence: Medication Possession Ratio (MPR) MPR = total days supply total # days evaluated X 100 Equals overall percent adherence value (medication availability) 353/365 X 100 = fill in%

12 MPR (cont) Pros: Easy to calculate Widely used adherence measure Cons: Participants get >1 fill in one day (ex: vacation supply) Change in prescribing directions Refills occur close to study termination

13 Between Fills Measures Days Between Fills Adherence Rate (DBR) DBR = (last claim date – 1 st claim date) – total days supply last claim date – 1 st claim date X Compliance Rate (CR) CR = total days supply – last days supply last claim date – 1 st claim date X 100 Refill Compliance Rate (RCR) RCR = total days supply last claim date – 1 st claim date X 100 Medication Possession Ratio, Modified (MPRm) MPRm = total days supply (last claim date – 1 st claim date) + last days supply X 100

14 Between Fills Measures Pros: Helps accounts for cutoff examination date period Consistent results seen with denominator of total study evaluation period Cons: In cases of single refills Smaller denominator Cannot assess/overestimation of adherence

15 Treatment Gaps total days study participation – total days supply total days study participation CMG = Ex: ( )/362 = 0.00 or total gap days Range: 0.0 = complete adherence 1.0 = complete non-adherence (-) values = surplus days (due to early refill or overfill) Continuous Measure of Medication Gaps (CMG) :Provides time patient does not have medication available (%)

16 Measuring Persistence Minimum-Refills Model Proportion of Days Covered Model Refill Sequence Model Anniversary Model

17 Minimum-Refills Model Persistence: Pt being dispensed a minimum # of Rxs per year

18 Minimum-Refills Model Pros: Might be useful for describing as needed medication use Cons: Does not account for length of time between refills Does not account for amount of time each refill should last

19 Proportion-of-Days-Covered Model Persistence: Enough medication dispensed to cover a specified proportion of days within a fixed interval (ex: 1 year) Example: 210 days supply/365 day interval = 58% PDC during the 1 st year

20 Pros: Relies on uniform evaluation period for all patients Shorter follow-up times create bias in PDC (higher numbers) Fewer opportunities for noncompliance/nonpersistence Cons: Cut-off arbitrary No info about timeliness of refilling or persistence Proportion-of-Days-Covered Model

21 Refill-Sequence Model Persistence: total duration of a continuous sequence of refills Unacceptable gap: Interval between the date of the 1 st Rx and refill considered to be nonpersistence PG: Permissible gap

22 Refill-Sequence Model Pros: Permit switches between Rxs with same indication Increased accuracy of measuring persistence when Information can be used to assess effect of an intervention aimed at improving persistency Cons: May not consider all refilling behavior across the observation period. Once an individual is classified as nonpersistent, future refilling behavior is no longer considered Patient could have discontinued or switched medications PG not well defined

23 Anniversary Model Persistence: Rx refilled within a specified interval (e.g., +/- 30 days) surrounding the anniversary of 1 st Rx Both patients are persistent at 1 year Patient 1: more consistent Monthly Fill 4 Fills

24 Anniversary Model Pros: Simple to use Accurate method for timeliness of medication refilling IF small refill gaps are small Cons: No consideration given to refills within the 1- year interval Patient is persistent, but not necessarily adherent

25 Summary

26 References Osterberg L, Blaschke T. Adherence to Medication. N Engl J Med 2005;353;5: Caetano PA, Lam JMC, Morgan SG. Toward a standard definition and measurement of persistence with drug therapy: Examples from research on statin and antihypertensive utilization. Clin Therapeutics 2006;28: Cramer JA, Roy A, Burrell A, et al. Medication compliance and persistence: Terminology and definitions. Value Health 2008;11. [Epub June 25, 2007] Sikka R, Xia F, Aubert RE. Estimating medication persistency using administrative claims data. Am J Managed Care 2005;11: Hess LM, Raebel MA, Conner DA, Malone DC. Measurement of adherence in pharmacy administrative databases: A proposal for standard definitions and preferred measures. Ann Pharmacother 2006;40: Hughes D, Cowell W, Koncz T, Cramer JA. Methods for integrating medication compliance and persistence in pharmacoeconomic evaluations. Value Health 2007;10(6): assessed March 20,

Download ppt "Defining Adherence and Persistence Sapna N. Patel UCSF Pharm. D. Candidate 2008 Preceptor Dr. Craig S. Stern March 21, 2008."

Similar presentations

Ads by Google