Managed Care - July 2008 - (Page 25) Direct and indirect adherence techniques have advantages and disadvantages I n a study of adherence methodologies published in the August 5, 2005, issue of the New England Journal of Medicine, in an article tiled “Adherence to Medication,” researchers from the Veteran Affairs Palo Alto Health Care System in Palo Alto, Calif., outlined the advantages and disadvantages of various techniques for measuring adherence. Methods of measuring adherence Test Direct methods Directly observed therapy Most accurate Patients can hide pills in their mouth, and then discard them; impractical for routine use Variations in metabolism and “white coat adherence” can give a false impression of adherence; expensive Requires expensive quantitative assays and collection of bodily fluids Advantages Disadvantages Measurement of the level of medicine or metabolite in blood Objective Measurement of biologic marker in blood Indirect methods Objective; in clinical trials, can also be used to measure placebo Patient questionnaires, patient self- Simple; inexpensive; the most usereports ful method in the clinical setting Pill counts Rates of prescription refills Objective, quantifiable, and easy to perform Objective; easy to obtain data Susceptible to error with increases in time between visits; results are easily distorted by the patient Data easily altered by the patient (e.g., pill dumping) A prescription refill is not equivalent to ingestion of medication; requires a closed pharmacy system Factors other than medication adherence can affect clinical response Assessment of the patient’s clinical response Electronic medication monitors Simple; generally easy to perform Precise; results are easily quantified; Expensive; requires return visits and tracks patterns of taking medidownloading data from medication cation vials Often easy to perform Marker may be absent for other reasons (e.g., increased metabolism, poor absorption, lack of response) Easily altered by the patient Susceptible to distortion Measurement of physiologic markers (e.g., heart rate in patients taking beta-blockers) Patient diaries When the patient is a child, questionnaire for caregiver or teacher Helps to correct poor recall Simple; objective Source: Osterberg, et al. Adherence to medication. N Engl J Med.2005;353(5):487–497. JULY 2008 / MANAGED CARE 25
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