Elsevier

Health Policy

Volume 59, Issue 1, January 2002, Pages 65-94
Health Policy

A review of the literature on the economics of noncompliance. Room for methodological improvement

https://doi.org/10.1016/S0168-8510(01)00178-6Get rights and content

Abstract

Therapeutic noncompliance is a major issue in health care, having important negative consequences for clinical outcome as well as for health-care costs. This paper reviews the literature on the economics of therapeutic noncompliance, identifies methodological shortcomings and formulates recommendations for future economic research in this area. Medication noncompliance was explored more extensively, as the majority of articles dealt exclusively with this aspect of therapy. Eighteen studies were assessed according to their definition and measurement of medication noncompliance, study design, and identification and valuation of costs and outcomes. Very diverse designs and often invalid methods for calculating costs were found. Medication noncompliance is often ill-defined and measured in an inaccurate way. The economic consequences of therapeutic noncompliance have rarely been investigated according to the standard principles of good economic evaluation. Six studies examined both costs and consequences of noncompliance in a cost–outcome description or a cost–benefits, cost–effectiveness or cost–utility analysis. Eight studies dealt with the economic value of compliance–enhancing interventions. In general, studies on the economic consequences of noncompliance lack methodological rigour and fail to meet qualitative standards. There is a clear need for more and better research on the impact of noncompliance, on the cost–effectiveness of interventions and the potential of compliance-enhancing interventions to improve patient outcomes and/or reduce health-care costs.

Introduction

Therapeutic compliance is often defined as ‘the degree to which patient behaviour (in terms of taking medication, following diets, executing lifestyle changes, …) is congruent with the recommendations of health-care providers’ [1]. For medication intake, compliance includes both regularity in dosing and timing of intake [2] and for some specific patient populations (e.g. HIV/AIDS patients) also food recommendations.

For the assessment of the economic consequences of noncompliance, costs and outcomes should be considered in a cost–benefit, cost–effectiveness or cost–utility analysis. Cost–benefit, cost–effectiveness and cost–utility analyses evaluate the ‘value for money’ of health interventions and compare these across interventions to assist decision makers in health-care in setting priorities between health interventions [3].

Therapeutic noncompliance entails costs due to the occurrence and consequent treatment of new or more morbid conditions and, in case of medication noncompliance, sometimes due to increased side-effects of medication. Under-dosing or extended time intervals between two medication intakes may increase morbidity, whereas over-dosing or shorter intervals between two medication intakes may increase unpleasant side-effects or toxicity of the medication. Moreover, buying medication without actually taking it implies a pure economic production cost. The same applies for appointment noncompliance. If the patient does not show up, there might be a slot in the doctor's consultation schedule. In contrast, if the untaken medication is not purchased or if the doctor can see another patient without appointment instead, costs are decreased, if no complications occur. The severity of the disease and the cost of the medication or the opportunity cost of the doctor will determine whether these savings offset the treatment costs of increased morbidity.

As for the outcomes, noncompliance has often been associated with increased clinical risk in chronic patient populations, in terms of increased morbidity and mortality [4], [5], [6], [7], [8], [9], [10]. Less is known about the quality of life associated with noncompliance. If noncompliance would have an obvious negative impact on quality of life, and a positive impact on costs, there is no doubt that noncompliance is undesirable from the economic point of view. Unfortunately, the picture is not that clear, especially with regard to quality of life issues. There is conceptual obscurity in the precise relationship between quality of life and noncompliance. Noncompliance may improve patients' quality of life, for instance when they deliberately adapt their medication schedule to their own lifestyle, or it may decrease their quality of life due to increased moribidity and/or side-effects. From the societal point of view, there might be a problem of negative externalities related to noncompliance, especially if it concerns noncompliance with treatments for infectious diseases. For instance, noncompliance with anti-retroviral therapy in HIV/AIDS may result in viral mutations and resistance, causing a major public health problem if other patients are infected. However, poor or good quality of life may also be a trigger for noncompliance [11], [12]. There might, moreover, be a recursive relation between quality of life and noncompliance, meaning, for instance, that noncompliance impairs quality of life, which in turn decreases compliance. Whether the relationship is recursive or non-recursive is unclear. The effect of noncompliance on the cost–effectiveness of the treatment, if effects are expressed in terms of quality of life, then becomes very ambiguous.

In practice, very few cost–effectiveness analyses correct for the factor of noncompliance [13], [14]. The correction usually occurs in a sensitivity analysis in which the impact of varying compliance rates on the cost–effectiveness ratio of an intervention is tested [14], [13], [15]. For example, Scharfstein et al. [14] found that the cost per Quality Adjusted Life Years (QALYs) gained, of a specific prophylaxis regimen for Mycobacterium avium complex in patients with AIDS, was $25 000/QALY, using efficacy results from a clinical trial. The cost amounted to $34 000/QALY with an assumed noncompliance rate of 20%. In this particular case, the increase in the cost per QALY had no impact on the cost–effectiveness of the regimen relative to other prophylaxis regimens, but it could impact upon its cost–effectiveness relative to interventions in other patient groups. An example of a prophylactic regimen in which the relative efficiency was influenced by the assumed noncompliance rate, was provided by Jönsson et al. [15]. With a compliance rate of 70%, the use of prophylactic misoprostol in patients with osteoarthritis and nonsteroidal anti-inflammatory drug-associated abdominal pain was less costly than no prophylaxis. Because the regimen was also more effective in preventing gastric ulcers, it was obvious that misoprostol administration was a preferable option. However, with an assumed compliance rate of 60%, the regimen became more costly relative to doing nothing.

The assessment of the economic consequences of medication noncompliance is hampered by a number of methodological problems. These problems relate to the definition and measurement of noncompliance, the study design for the economic evaluation of noncompliance, the identification, measurement and valuation of noncompliance-related costs and outcomes and the consideration of compliance-enhancing interventions.

Section snippets

Objective

The main objective of this study is to review the literature on the economics of therapeutic noncompliance in patients and explore the methodological problems in studying the economic consequences of non-compliance. Recommendations for future economic research in this area will be formulated.

Methods and materials

A literature search was performed using Medline 1974-2000, CINAHL 1982-2000, PsychINFO 1966-2000 and reference lists of retained articles. A combination of the following key-words was used: (non-)compliance, (non-)adherence, cost*, economic*, financial. Eighteen studies on the economics of patient noncompliance with therapeutic regimens were found. Five studied the costs of noncompliance in general, seven the costs of medication noncompliance in specific diseases and six the cost–effectiveness,

Results

In the literature on the economics of noncompliance, a number of problems were identified. These problems relate to the definition and measurement of medication noncompliance, study design, cost calculation, outcome measurement and consideration of determinants of noncompliance and compliance-enhancing interventions.

Recommendations

It is clear from the above review that the existing studies on the economics of medication noncompliance lack methodological rigour. Table 4 lists a number of criteria according to which economic evaluations of noncompliance can be assessed.

Conclusion

Therapeutic noncompliance is a behaviour that leads to increased health-care costs and decreased cost–effectiveness of interventions. For both clinicians, policy-makers in health-care and patients, it is important to take the impact of noncompliance on the cost–effectiveness of interventions into account. Studies about the economic consequences of noncompliance are generally performed in a very elementary way. Costs are not valued according to the standard principles of cost calculation, and

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