Measuring Adherence

1
Measuring Adherence

• Jonathan Shuter, M.D.

Treatment Adherence Network Meeting 2/27/01
2
Measuring Adherence--One Extreme

• I firmly believe that if the whole materia
  medica as now used could be sunk to the bottom of
  the sea, it would be all the better for
  mankind--and all the worse for the fishes.

1860 Oliver Wendell Holmes to the Massachusetts
Medical Society
3
Measuring Adherence--The Other Extreme

• D.O.T.

4
Measuring Adherence--The Middle Ground

• Methods that quantify missed and taken doses
• Methods that measure physiologic effects
• Methods that assess systemic blood levels of drug

5
Self-Report
Pros
Cons

• Cheap
• Correlated with virologic outcomes (report of
  non-adherence is more reliable than report of
  adherence)

• Overestimates adherence

6
Clinician-Estimated Adherence
Pros
Cons

• Cheap

• Most poorly correlated of all measures with
  actual adherence

PROVIDERS ARE TERRIBLE JUDGES OF ACTUAL ADHERENCE
AND OF THEIR PATIENTS ABILITY TO ADHERE!
7
Pill Counts
Pros
Cons

• Cheap
• Useful adjunct to self-report

• Overestimates adherence
• Pill dumping
• Time consuming
• Casts provider in role of medication monitor, not
  ally/advocate

8
Pharmacy Records
Pros
Cons

• Cheap
• Useful adjunct to self-report

• Cannot stand alone as adherence measurement
  method
• One patient may use many pharmacies
• Picking up prescriptions does not equate with
  taking medications
• Patients may have other sources of medications

9
Electronic Monitoring
Pros
Cons

• Best correlation with virologic outcomes
• Data is available in a computer accessible format
• Allows more detailed view of non-adherence
  patterns (weekends, nighttime, etc.)

• Expensive
• Poor patient acceptance
• Not infallible (patients can open bottle and not
  take pill)
• Not compatible with pillbox
• Usually only measures one medication

10
Measuring Adherence--The Middle Ground

• Methods that quantify missed and taken doses
• Methods that measure physiologic effects
• Methods that assess systemic blood levels of drug

11
Indirect Laboratory Markers

• AZTgt Increased MCV
• ddIgt Increased uric acid
• Indinavirgt Increased bilirubin

12
Laboratory Markers

• Viral load
• CD4
• Genotypic/phenotypic resistance

13
Measuring Adherence--The Middle Ground

• Methods that quantify missed and taken doses
• Methods that measure physiologic effects
• Methods that assess systemic blood levels of drug

14
Plasma Levels
Pros
Cons

• Correlates with virologic outcomes
• Only method that ensures that the patient
  actually ingested the drug
• May allow insight into absorption or drug
  interaction problems

• Very expensive
• Levels are extremely variable
• Only provides information about the last dose

15
Montefiore Data
16
Montefiore Data

• 30/106 (28.3) patients prescribed ART responded
  Never miss medications, every time they were
  interviewed.
• These patients are not distinguished by any
  specific characteristic measured in the study.
  There are trends toward underrepresentation of
  females and IDUs in this group.
• Analyzed variables include age, gender,
  ethnicity, HIV risk behavior, AIDS, adverse
  effects, and depression score.

17
Conclusions

• There is no perfect method or combination of
  methods available to measure adherence
• Nevertheless, numerous methods of measurement
  correlate with virologic outcomes, and thus
  provide useful information
• Some method of adherence measurement should be
  used for all patients, but decisions regarding
  which method/s should be individualized