Adherence to Long-Term Therapies - Evidence for Action
(2003; 211 pages) View the PDF document
Table of Contents
View the documentPreface
View the documentAcknowledgements
View the documentScientific writers
View the documentIntroduction
View the documentTake-home messages
Open this folder and view contentsSection I - Setting the scene
Open this folder and view contentsSection II - Improving adherence rates: guidance for countries
Close this folderSection III - Disease-Specific Reviews
Open this folder and view contentsChapter VII - Asthma
Open this folder and view contentsChapter VIII - Cancer (Palliative care)
Close this folderChapter IX - Depression
View the document1. Research methods: measurement of adherence and sampling
View the document2. Rates of adherence
View the document3. Predictors of adherence
View the document4. Interventions to improve adherence
View the document5. Clinical implications and need for further research
View the document6. References
Open this folder and view contentsChapter X - Diabetes
Open this folder and view contentsChapter XI - Epilepsy
Open this folder and view contentsChapter XII - Human immunodeficiency virus and acquired immunodeficiency syndrome
Open this folder and view contentsChapter XIII - Hypertension
Open this folder and view contentsChapter XIV - Tobacco smoking cessation
Open this folder and view contentsChapter XV - Tuberculosis
Open this folder and view contentsAnnexes
Open this folder and view contentsWhere to find a copy of this book
 

1. Research methods: measurement of adherence and sampling

As is the case when attempting to measure patient behaviour in many other contexts, it is difficult to derive accurate estimates of patient adherence to medication for depression. Across studies, several techniques have been used including clinician estimation or patient self-report, pill-counting, estimation of blood levels of drug, metabolite or tracer substance, and the use of electronic monitoring systems that record pill dispensing. Two studies directly compared methods of measurement. In 1990 Kroll et al., using a small sample of patients with mixed diagnoses, demonstrated that levels of medication in the blood correlated with clinical outcome, and that many patients who claimed to be taking a medication regularly had low levels of it in their blood (3). In 2000, George et al. compared four methods of assessment in depressed patients treated by primary care practitioners, and were able to show that an event monitoring system (EMS) that electronically counted the amount of medication dispensed from its container was the most sensitive method of measuring adherence, although the specificity of a patient report of nonadherence was also high (4). Estimations of plasma levels of drugs and their metabolites were less useful. Although these types of measure overcome some of the bias associated with either physician observation or patient self-report, they still lack some of the features required of a "gold-standard" measure (i.e. being direct, objective and unobtrusive).

The second important methodological issue is the nature of the patient samples studied. Much research has been conducted on hospital outpatients or inpatients, or patients recruited into randomized trials to test the efficacy of medications. This pre-selection bias makes it very unlikely that the patients in these studies represent the true population of depressed patients receiving treatment in primary care settings. This makes it hard to generalize from the results of these studies.

to previous section
to next section
 
 
The WHO Essential Medicines and Health Products Information Portal was designed and is maintained by Human Info NGO. Last updated: October 7, 2014