Download Research Methods Workshop: Measuring Exposure and Adherence

Medication Adherence:
Measuring the Immeasurable
Zachary A. Marcum, PharmD, MS, BCPS
Assistant Professor
School of Medicine (Geriatrics)
University of Pittsburgh
May 4, 2013
Financial Disclosures
• Grant funding from AHRQ and NIH/NIA
• No conflicts of interest
Topics to Discuss
• Discuss the use of self-reported methods
to measure medication adherence in
clinical research
• Discuss the use of pharmacy claimsbased methods to measure medication
adherence in clinical research
How is Adherence Measured?
 Self-Report
• Interviews
• Survey instruments
 Pharmacy Claims
 Electronic Monitoring
 Pill Counts
 Drug Levels
 Biologic Response
•No gold standard
•Use of 2+ measures
recommended: self-report
+ objective measure(s)
*Not often done in clinical
practice*
Self-Report – Pros/Cons
• Most commonly used method
• Strengths:
– Simple, inexpensive and convenient
– Provides information on patterns of actual medication
use and/or reasons for deviations from instructions
– Good specificity for non-adherence
– Moderately related to health outcomes
• Limitations:
–
–
–
–
Social desirability and reporting biases
Impact of cognitive impairment
Modest sensitivity for non-adherence
Many measures exist (variable psychometrics)
Examples of Methods/Instruments for Measuring Internal Barriers
to Medication Non-adherence in Adults
Medication Non-adherence Phenotype
Method/ Instrument
Adherence Estimator
Establishing
relevance of
the behavior
Evaluating
risks and
benefits of
the
treatment
√
√
Processing
of complex
information
Holding
inaccurate,
irrational, or
conflicting
normative
beliefs about
medications
Perceived lack
of therapeutic
effectiveness
√
Medi-Cog
Morisky Medication
Adherence Scale
Beliefs about
Medications
Questionnaire BMQ
(General)
Beliefs about
Medications
Questionnaire BMQ
(Specific)
Ecologic Momentary
Assessment
Remaining
vigilant
toward
behavior
√
√
√
√
√
Marcum ZA, Sevick MA, Handler SM. JAMA 2013; in press.
√
√
The Adherence Estimator®
McHorney CA. Curr Med Res Opin 2009;25:215-38.
Morisky DE et al. J Clin Hypertens 2008;10:348-54.
Prevalence & Correlates of
Self-reported Medication Non-adherence
• Design: Cross-sectional
• Data Source: Health ABC Study
• Subjects: 897 participants with DM, CHD, +/HTN from Year 10 (06-07) and Year 11 (07-08)
• Outcomes: MMAS-4 and CRN-2
• Correlates: Demographics, health status, access
to care
• Statistics: Stepwise selection with backward
elimination; multivariable logistic regression
Marcum ZA, et al. Res Soc Admin Pharm 2013; Epub ahead of print.
Prevalence & Correlates of Self-reported
Medication Non-adherence among Older
Adults with CHD, DM, +/- HTN
Prevalence
Correlates
Black race
Cancer
History of falls
Sleep disturbances
Hosp. in previous 6 mos.
Unmarried
Worse self-reported health
Needs poorly met by income
MMAS-4
CRN-2
40.7%
7.7%
P=0.002
P=0.04
P=0.02
P=0.04
P=0.005
----
P=0.005
----P=0.049
P=0.04
P=0.02
Marcum ZA, et al. Res Soc Admin Pharm 2013; Epub ahead of print.
Self-Report – Summary
• May be very effective initial screen for nonadherence issues
• Multiple measures likely needed
• Patient-centered interventions can follow
• Must understand what is actually being
measured
Topics to Discuss
• Discuss the use of self-reported methods
to measure medication adherence in
clinical research
• Discuss the use of pharmacy claimsbased methods to measure medication
adherence in clinical research
Pharmacy Claims – Pros/Cons
• Strengths:
–
–
–
–
Objective; inexpensive
Large samples possible; population-level
Data readily available in closed systems (e.g., VA, HMO)
Unobtrusive; free from social desirability/reporting biases
• Limitations:
– Wide variability in definitions used in literature
– Unique barriers for defining measurement in older
adults (e.g., SNF/hospitalization stays)
– Calculation depends on several assumptions
– Misses OTC medications (e.g., NSAIDs)
– $4 generic medication fills
– Filling prescription ≠ ingesting medication
Pharmacy Claims – Examples
MPR = Medication Possession Ratio
PDC = Proportion of Days Covered
The proportion of days in the measurement period
“covered” by prescription claims for the same
medication or another in its therapeutic category.
CMG = Continuous Measure of medication Gaps
Andrade SE, et al. Pharmacoepidem Drug Saf 2006;15:565-74.
Pharmacy Claims – Quality Measures
• Central to the Center for Medicare and Medicaid
Services (CMS) Star Rating program  PDC
• In order for Medicare Advantage health plans to
achieve five stars (i.e., financial incentives), more
than 75% of covered beneficiaries will be required
to obtain at least 80% of the medication prescribed
to them
• 3 medication classes: oral diabetes, statin, and
hypertension medications
Steiner JF. Arch Intern Med 2012;157:580-5.
Impact of Multiple Pharmacy Use on
Medication Adherence
• Design: Cross-sectional
• Data Source: Medicare Part D; nationally
representative sample
• Subjects: 926,956 beneficiaries aged ≥65
continuously enrolled in FFS Medicare and Part
D in 2009
• IV: Multiple pharmacy use (concurrent vs
sequential)
• Outcome: Medication adherence (PDC≥0.80) for
chronic medications
• Statistics: Propensity-score weighted analysis
Marcum ZA, et al. Data Not Published; Under Review.
Marcum ZA, et al. Data Not Published; Under Review.
Guidance & Review
Sattler ELP, et al. Drugs Aging 2013;Epub ahead of print.
Peterson AM, et al. Value Health 2007;10:3-12.
Pharmacy Claims – Summary
• Increasingly common approach used for
large, population-based samples
• Can supplement other measures
• Many measurement factors can affect the
outcome (e.g., hospitalization, SNF stay)
• Must understand what is actually being
measured
Topics to Discuss
• Discuss the use of self-reported methods
to measure medication adherence in
clinical research
• Discuss the use of pharmacy claimsbased methods to measure medication
adherence in clinical research