Measuring Adherence

Jonathan Shuter, M.D.

Treatment Adherence Network Meeting 2/27/01

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

Measuring Adherence--The Other Extreme

D.O.T.

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

Self-Report

• Cheap• Correlated with

virologic outcomes (report of non-adherence is more reliable than report of adherence)

• Overestimates adherence

Pro’s Con’s

Clinician-Estimated Adherence

• Cheap • Most poorly correlated of all measures with actual adherence

Pro’s Con’s

PROVIDERS ARE TERRIBLE JUDGES OF ACTUAL ADHERENCE AND OF THEIR PATIENTS’ ABILITY TO ADHERE!

Pill Counts

• Cheap• Useful adjunct to self-

report

• Overestimates adherence– “Pill dumping”

• Time consuming• Casts provider in role

of medication monitor, not ally/advocate

Pro’s Con’s

Pharmacy Records

• 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

Pro’s Con’s

Electronic Monitoring

• 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

Pro’s Con’s

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

Indirect Laboratory Markers

• AZT=========> Increased MCV

• ddI==========> Increased uric acid

• Indinavir======> Increased bilirubin

Laboratory Markers

• Viral load

• CD4

• Genotypic/phenotypic resistance

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

Plasma Levels

• 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

Pro’s Con’s

Montefiore Data

020406080

100120140

Nev

er

Rar

ely

Som

etim

es

Oft

en

Alw

ays

How often do you miss doses of your HIV medications?

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.

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

For more HIV-related resources, please visit www.hivguidelines.org