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Construct Overview of Compliance/Adherence

Please note that this section is an archive and is no longer being updated.

Background

Patient compliance or adherence with treatment is an important issue in the provision of medical services. It affects the ability to prevent illness or maintain wellness among patients.¹ Noncompliance with medications causes 125,000 Americans to die each year and is associated with 10% of hospital admissions.² Noncompliance may be defined as, "the failure of the patient to fulfill the clinical prescription as it was intended by the practitioner."³ Simply stated, patients are adherent when they follow what their health professionals advise. A patient may be adherent to any number of medical regimens including medication, diet, healthcare behavior, appointment follow-ups, or exercise.⁴

Interventions to improve adherence include self-monitoring, patient education, social support, contracts, follow-ups via telephone, and tailoring.¹ Adherence improvement relies on the joint efforts of patients, providers and healthcare organizations.

VA Relevance

Research suggests that taking multiple medications and poor patient-provider relations may strongly influence nonadherence among the older population.⁵ Nonadherence in the older population is of particular importance due to the large amount of medications that older persons consume. Medication use (and especially use of multiple medications) increases with age. Adherence among older persons is also affected by variables associated with aging, such as physical and cognitive decline.⁵

Measurement

There is currently no gold standard for assessment of adherence, and each method has advantages and disadvantages. Methods include biological assays, pill counts, electronic monitors used to record the number of times a pill bottle is opened, administrative data based on medical charts and pharmacy records, and self-report from either the patient or a proxy such as a family member.^4-5

Biological assays and electronic monitors are useful, but are more expensive and sometimes impractical. Biological assays can be invasive and influenced by when patients last consumed medications, while electronic monitors have the potential to underestimate adherence if patients remove more than one dose at a time or affect utilization because they are inconvenient to use.^4-5 In addition, there are issues such as cost, malfunction, and loss associated with these monitors. Pill counts may be influenced by the incorrect labeling of bottles, ordering new refills before the pills are depleted, or patient objection. Medical records can be efficient, although they be biased by the physicians' perceptions or liability concerns.⁴ Pharmacy records may be used, but claims data are subject to validity and reliability issues.⁵ Self-report methods, including interviews and questionnaires, can be efficient and inexpensive. However, self-report may be affected by social desirability bias and in the case of interviews, the bias of the interviewer.

DiMatteo (2004) recently conducted a meta-analysis of 569 studies that reported adherence to non-psychiatric medical treatment as advised by a nonpsychiatric physician.⁴ The overall nonadherence rate was 24.8% and that the most frequently used methods for measuring adherence were medical record, self-report, and pill count. DiMatteo specifically addressed the issue of variation in reported adherence due to sample characteristics, publication time period, disease, regimen, measurement method, and patient demographics. After controlling for confounders, adherence was significantly higher in studies with smaller samples and adult samples, more recent studies, and those involving medication regimens (i.e. versus health behaviors). Adherence was also higher for some diseases versus others, whereby it was the highest in studies of HIV. Patient demographics played a minor role in influencing reported adherence. DiMatteo's meta-analysis highlights the importance of considering many methodological issues when measuring adherence and interpreting results.

Among these measurement methods available to determine compliance, we have provided additional information on the self-report and interviewer-administered measures. Through literature review, METRIC has identified three such commonly used compliance/adherence instruments and ranked them according to number of citations, as determined by the ISI Web of Knowledge.⁶ What follows is a brief summary of each instrument and three applicable references, including the developmental source.

Most Frequently Cited Instruments

1. Morisky Scale
   [191 Citations]
2. Adult AIDS Clinical Trials Group (AACTG) Adherence Instruments
   [139 Citations]
3. General Adherence Scale (GAS)
   [139 Citations]

References

1. Miller NH, Hill M, Kottke T, Ockene IS. The multilevel compliance challenge: recommendations for a call to action. A statement for healthcare professionals. Circulation. 1997 Feb 18;95(4):1085-90. [Abstract]
2. Possidente CJ, Bucci KK, McClain WJ. Motivational interviewing: a tool to improve medication adherence? Am J Health Syst Pharm. 2005 Jun 15;62(12):1311-4. [Abstract]
3. Hays RD, DiMatteo MR. Key issues and suggestions for patient compliance assessment: Sources of information, focus of measures, and nature of response options. 1987. The Journal of Compliance in Health Care 2(1), 37-52. [No Abstract Found]
4. DiMatteo MR. Variations in patients' adherence to medical recommendations: a quantitative review of 50 years of research. Med Care. 2004 Mar;42(3):200-9. [Abstract]
5. Vik SA, Maxwell CJ, Hogan DB. Measurement, correlates, and health outcomes of medication adherence among seniors. Ann Pharmacother. 2004 Feb;38(2):303-12. [Abstract]
6. Chesney MA, Ickovics JR, Chambers DB, Gifford AL, Neidig J, Zwickl B, Wu AW. Self-reported adherence to antiretroviral medications among participants in HIV clinical trials: the AACTG adherence instruments. Patient Care Committee & Adherence Working Group of the Outcomes Committee of the Adult AIDS Clinical Trials Group (AACTG). AIDS Care. 2000 Jun;12(3):255-66. [Abstract]
7. ISI Web of Knowledge, Accessed June 2005. Available URL: http://isi01.isiknowledge.com/portal.cgi/wos/.