US Pharm
. 2012;37(4)(Compliance suppl):12-14.

Compliance is the process whereby the patient follows the prescribed and dispensed regimen as intended by the prescriber and dispenser. It is defined as “the extent to which a person’s behavior (in terms of taking medications, following diets, or executing lifestyle changes) coincides with medical or health advice.”1 Compliance with therapy is an indication of a positive behavior in which the patient is motivated sufficiently to adhere to the prescribed treatment because of a perceived self-benefit and positive outcome.

Noncompliance is a great problem facing the health care system. It is estimated that noncompliance costs the economy anywhere between $100 and $300 billion annually in the United States, including the costs from avoidable hospitalizations, nursing home admissions, and premature deaths.2 This dilemma greatly affects pharmacists, who are increasingly providing support and counseling to patients regarding their therapeutic regimen.

The process of seeking a diagnosis and treatment, receiving the treatment, and following the treatment and advice occurs in stages, with the possibility of noncompliance arising at each stage.3 About 75% of patients are noncompliant in one way or another.3,4 Primary noncompliance occurs when the patient does not fill the prescription.3 About a third of noncompliant patients fall into this category.4 Secondary noncompliance can occur in a number of ways, including missing a dose, stopping the drug altogether, taking the drug at the wrong time, and using medication devices incorrectly.3 Research has shown that about 30% of patients simply forget to take their medication and another 30% do not complete the entire course.4 At the other end of the spectrum are the hypercompliant patients who take the prescribed medication at a level that is higher than the prescriber or dispenser intended.

Compliance, Adherence, and Concordance

The terms compliance, adherence, and concordance are often used interchangeably in practice. While related, these terms have somewhat different meanings.

Compliance is defined as “the extent to which the patient’s behavior matches the prescriber’s recommendations.”5 Its use implies the “lack of patient involvement” and is associated with negative characteristics such as yielding and submission.3,5 On the same note, noncompliance can imply disobedience.3 The definition of compliance assumes that all medical advice and drugs given to the patient are good for the patient and that the patient should adjust his or her behavior to follow the therapeutic regimen.

Adherence is defined as “the extent to which the patient’s behavior matches the agreed recommendations from the prescriber.”6 It takes the definition of compliance one step further by stressing the need for agreement.6 In this context, the patient has the flexibility to decide whether to adhere to the doctor’s recommendations. Nonadherence is not associated with blame on the part of the patient.6

The term concordance is different in that it relates to the behavior between the doctor and the patient, whereas adherence and compliance are used with respect to the medication-taking nature of the patient.6 It was introduced by the Royal Pharmaceutical Society of Great Britain and is more commonly used in the United Kingdom. It refers to an agreement that is reached after a discussion between the health care professional and the patient in which the health care professional respects the feelings and beliefs of the patient with regard to whether, when, and how the medications are to be taken.7

The traditional term compliance will be used throughout this article since most of the literature reviewed for this paper refers to compliance.

Measuring Compliance

Statistics on the rates of compliance are not accurate since a gold standard for the measurement has not yet been established. Various direct and indirect methods have been used over the years, all with their own drawbacks, and therefore well-designed, standardized research on compliance is limited.8

Direct methods include various assays conducted using biological markers and tracer compounds to detect medication levels in the bodily fluids. These methods are more accurate than indirect ones but are costly and require close monitoring. Direct methods of measuring compliance are most practical in hospitals and other inpatient settings. A common problem encountered with the measurements is that they do not account for the variability of pharmacokinetic factors of different medications and different individuals.8

Indirect methods are subject to greater bias and are not as accurate as direct methods. Most of the literature published on compliance is derived from data based upon indirect measurements.3 These include interviews, diaries, pill counts, prescription filling dates, and therapeutic and preventive outcome measures. Patient self-reports and family interviews are highly subjective and tend to overestimate compliance, but may provide useful data in customizing that patient’s medication.3 Pill counts are useful in assessing about 80% of true compliance, but they encourage pill dumping.3 Prescription refill dates are only accurate if the patient uses the same pharmacy to fill prescriptions and the database is accurate. However, filling a prescription on time does not necessarily mean that the patient is taking the medication correctly, or taking it at all.3

Using therapeutic outcomes to determine the degree of compliance may encourage what is known as the toothbrush effect (i.e., patients may load up on or adhere to medication regimens a few days before the next visit to their health care professional). Additionally, the condition of the patient may change due to factors other than the medication, and the resulting therapeutic outcome may be skewed. Medication event monitoring systems (MEMS) are newer, electronic forms of monitoring that note the time and date when a medication vial was opened. Once again, however, this may not necessarily mean the patient took the medication at the time the vial was opened.3

Causes of Noncompliance

There are two types of noncompliance: intentional and nonintentional. In nonintentional compliance, the patient is unaware that he or she is not taking the medication as prescribed.

A large number of variables that may contribute to poor compliance have been described by various authors. However, none of these appear to be strong enough or consistent. The referral process, clinical setting, and therapeutic regimen do not seem to affect adherence to a great extent, although in some cases, attending a specialized or private clinic may increase compliance.3,9 A significant difference has been noted between compliance with twice-daily and thrice-daily regimens. Compliance also drops significantly when the duration of treatment exceeds 5 days.9 Other factors that may affect compliance are listed in TABLE 1.3,9

Over the years, various models of health behavior have been described by numerous authors. Variables of these health care models can often be tied in with predicting and understanding patient compliance.

Health Behavior Models and Compliance

In the Health Belief Model, compliance is determined upon the knowledge and attitudes of the patient.9 The four main concepts that direct a patient’s assessment of the potential costs and benefits are given in TABLE 2.10

This model explains about 10% of the variance in the compliance variable. Incorporating the variables from the theory of reasoned action explains a further 19% of the variance.11 The theory of reasoned action proposed by Ajzen and Fishbein states that sufficient knowledge and a full intention to practice healthy behavior (e.g., compliance) are important in producing a healthy outcome.12 A more recent version of the Health Belief Model incorporates two more variables10:

Self-efficacy: The patient’s belief that he or she is capable of performing the required action.

Cues to action: Reminders for the patient to perform the action.

Building upon these theories is the Social Cognitive Theory, which transcends individual factors and incorporates both environmental and social factors.10 This theory proposes that there is a continuous dynamic interaction between the individual, his or her environment, and the individual’s behavior.10 Based upon this model, patients who experience a noticeable benefit with initial treatment are more likely to comply with the remainder of their therapy.

Similarly, the Health Decision Model combines the Health Belief Model and the Patient Preference Model, particularly decision analysis, the behavioral decision theory, and health beliefs.13 The factors that affect patient compliance according to the Health Decision Model are listed in TABLE 3.13

Improving Compliance

Since the data on the extent and causes of noncompliance are not complete, attempts to enhance compliance are hindered. It is important to identify the cause for noncompliance before a plan to improve compliance can be implemented.14 When developing a compliance plan, it is useful to note that interventions that combine cognitive, behavioral, and affective components are more effective than those with a single component.15

Various studies have shown that patients respond better when a therapeutic plan is developed with their participation.14 Simplification of the drug therapy, patient education regarding both the illness and the medication, continued patient reminders of the therapy’s value, as well as benchmarks set to evaluate the success or failure of the therapy, have all had a positive effect on compliance.11,14 The discussion should include a description regarding the complexity of the regimen and the benefits and side effects associated with the drugs prescribed. Health care practitioners should take into account the time and fiscal constraints the patient may face in following the therapeutic regimen as well as other factors that may modify the patient’s perception of the likelihood of compliance.11 Compliance aids such as organizers and reminders including blister packs, calendars, dosage counters, special containers, controlled-delivery devices, and metered-dosage forms may be introduced to patients who simply forget to take their medication.3

Another study concentrated on the different aspects of the doctor–patient relationship that may improve patient compliance.3 Factors that were identified included the doctor’s friendliness and approachability, the enhancement of patient centeredness, the improvement of the doctor’s teaching skills, recognizing any spiritual and psychological dimensions that may be of importance to the patient, as well as the accurate recognition of the patient’s problem by the doctor.3 While this study discussed the role of the physician, the same features will apply to pharmacists who have an ever-increasing role to play in the counseling of patients and improving compliance.

It is difficult to establish accurate and reliable data on the rates of noncompliance since the methods used to measure compliance all have issues. Pharmacists should try to identify which factors are leading to noncompliance in an individual before establishing ways to increase compliance rates.


1. Haynes RB. Introduction. In: Haynes RB, Taylor DW, Sackett DL, eds. Compliance in Health Care. Baltimore, MD: Johns Hopkins University Press; 1979.
2. Improving Prescription Adherence Is Key to Better Health Care: Taking Medicines as Prescribed Can Lower Costs and Improve Health Outcomes. Washington, DC: Pharmaceutical Manufacturers Association (PhRMA); January 2011. Accessed February 1, 2012.
3. Vermeire E, Hearnshaw H, Van Royen P, Denekens J. Patient adherence to treatment: three decades of research. J Clin Pharm Ther. 2001;26:331-342.
4. Just What the Doctor Ordered: Taking Medicines as Prescribed Can Improve Health and Lower Costs. Washington, DC: PhRMA; March 2009. Accessed February 1, 2012.
5. Horne R, Weinman J, Barber N, et al. Concordance, adherence and compliance in medicine taking. Report for the National Co-ordinating Centre for NHS Service Delivery and Organisation R & D (NCCSDO). December 2005. University of Leeds, School of Healthcare. Accessed February 19, 2012.
6. Bell JS, Airaksinen MS, Lyles A, et al. Concordance is not synonymous with compliance or adherence. Br J Clin Pharmacol. 2007;64:710-711.
7. Dickinson D, Wilkie P, Harris M. Taking medicines: concordance is not compliance. BMJ. 1999;319:787.
8. Morris LS, Schulz RM. Patient compliance—an overview. J Clin Pharm Ther. 1992;17:283-295.
9. Griffith S. A review of the factors associated with patient compliance and the taking of prescribed medicine. Br J Gen Pract. 1990;40:114-116.
10. Chisolm SS, Taylor SL, Gryzwacz JG, et al. Healthcare models: a framework for studying adherence in children with atopic dermatitis. Clin Exp Dermatol. 2010;35:228-232.
11. Ried LD, Christensen DB. A psychosocial perspective in the explanation of patients’ drug-taking behavior. Soc Sci Med. 1988;27:277-285.
12. DeJoy D. Theoretical models of health behavior and workplace self-protective behavior. J Saf Research. 1996;27:61-72.
13. Eraker SA, Kirscht JP, Becker MH. Understanding and improving patient compliance. Ann Intern Med. 1984;100:258-268.
14. Bond WS, Hussar DA. Detection methods and strategies for improving medication compliance. Am J Hosp Pharm. 1991;48:1978-1988.
15. Roter DL, Hall JA, Merisca R, et al. Effectiveness of interventions to improve patient compliance: a meta-analysis. Med Care. 1998;36:1138-1161.

To comment on this article, contact