The Economic Burden of COPD Exacerbations

Acute exacerbations of chronic obstructive pulmonary disease (COPD) impose a significant burden on society in terms of morbidity, mortality, reduced quality of life, health care expenditure and costs of productivity loss (1). The main effective interventions in the treatment of COPD exacerbations are increased doses of inhaled bronchodilators, systemic corticosteroids, antibiotics if signs of bacterial infection are present and non-invasive ventilation. Other modes of delivery (e.g., involving home support) are also being implemented. In addition to the effectiveness of various approaches to treating COPD exacerbations, policy makers and health care payers are concerned about their costs in a context of spiraling health care costs and limited resources.

To date, little is known about the costs of treating COPD exacerbations in terms of the level of costs, the distribution of costs between health care settings, and the cost drivers of treating COPD exacerbations. Cost studies are important in underlining the importance of COPD exacerbations to society when considered alongside their impact on morbidity and mortality. Furthermore, cost studies may allow the identification of the drivers of societal costs. Finally, cost data can be fed into economic evaluations, so that decision makers can ascertain the efficiency of various approaches to treating COPD exacerbations by examining their effectiveness in relation to their costs.

The paper by Toy et al. (2) reviewed the recent literature on economic costs of COPD exacerbations. The aim of this Editorial is to discuss several methodological issues that need to be addressed when estimating the economic burden of COPD exacerbations. Issues relate to: type of cost study, patient sample, study design, data collection, scope of included costs, costs and charges.

STUDY TYPE

A cost study of COPD exacerbations can take the form of a cost-of-illness analysis or a cost analysis (3). A cost-of-illness analysis quantifies the economic burden of COPD exacerbations to society by measuring the costs of diagnosing and treating COPD exacerbations as well as the costs arising as a result of COPD exacerbations (for instance, productivity loss due to time taken off work). Such studies measure direct costs related to health care resource use (e.g., medication, contacts with healthcare professionals and hospitalization), direct non-health-care costs (e.g., transportation to the health care professional), and indirect costs (e.g., costs of days lost to education, costs of productivity loss of patients and family/friends who care for patients). A cost analysis compares two or more approaches to diagnosis and treatment of COPD exacerbations (for instance, two different antibiotics).

PATIENT SAMPLE

Diagnosing a COPD exacerbation is complex because exacerbations are heterogeneous and there is debate about the definition of an exacerbation. In practice, the diagnosis is generally based on patients’ self-reported clinical symptoms and high-quality sputum specimens are not always available. This implies that exacerbations are not always identified as such and appropriate treatment is not always administered. (4) Incorrect diagnosis and inappropriate treatment are likely to have significant cost and health consequences.

The wide variety of patients suffering from exacerbations challenges the enrollment of patients in a cost study. Studies can be based on a representative national sample or enroll a specific group of patients. Differences in patient characteristics matter because cost estimates are influenced by, for instance, age of the study population. Therefore, cost studies need to report the profile of included patients to enable readers to assess generalisability of cost estimates to their patient population.

Cost studies need to take account of the chronic nature of COPD and associated exacerbations (5). COPD patients typically suffer from 1 to 4 exacerbations per year, with the frequency of exacerbations increasing with the severity and duration of COPD. Exacerbations also worsen the natural history of COPD. Therefore, cost studies need to have an adequate time horizon. Existing cost studies have tended to adopt a prevalence approach, measuring costs attributable to patients suffering from COPD exacerbations during a given time interval. Alternatively, studies could take an incidence approach and quantify lifetime costs of COPD exacerbations from onset to death.

STUDY DESIGN

There is a need to separate the costs of exacerbations from the costs of underlying COPD or co-morbidities. Generally, existing cost studies have identified patients suffering from exacerbations, but did not have a control group of patients without exacerbations. Such case series analyses that focus on identified patients only may be misleading in the case of COPD exacerbations, where diagnosis is complex and attribution of healthcare resource utilization to the disease is difficult. Instead, studies should compare patients suffering from exacerbations with equivalent patients who do not suffer from COPD exacerbations. Such a case-control approach seems better suited in that it is more inclusive and allows identification of additional resource use related to exacerbations.

DATA COLLECTION

Data can be collected prospectively/retrospectively from patient medical records, a survey, a claims database or the literature. The reliability of survey data is hindered by patients’ ability to recall resource utilization. Claims data may suffer from missing data and incorrect diagnostic coding of claims. Studies need to set up a prospective collection of primary data on resource use and costs. This type of analysis can be considered to be more reliable than retrospective analyses of patient medical records or claims databases. Alternatively, modeling approaches can be considered that are based on high-quality data, closely reflect real-life practice and the evolution of COPD exacerbations in patients.

SCOPE OF COSTS

The literature review has demonstrated that inpatient costs represent the principal cost driver of COPD exacerbations (2). As hospitalization is generally indicative of treatment failure, these estimates highlight the potential savings that can be attained from preventing treatment failure. In other words, considerable savings can be generated by more effective antibiotics that allow patients to be managed in primary care and that prevent treatment failure and hospitalization. The literature also shows that the acquisition costs of antibiotics make up a limited percentage of treatment costs (6).

The scope of included costs in existing cost studies is generally restricted to direct health care costs associated with exacerbations. Few studies consider indirect costs arising as a result of COPD exacerbations. The omission of indirect costs is of minor concern given that the population of patients that experience COPD exacerbations tends to be elderly. Moreover, in this population of elderly and frail patients, it is not straightforward to distinguish lost productivity of caregivers related to COPD exacerbations from lost productivity related to general illness. Nevertheless, in order to gain an insight into the economic burden of COPD exacerbations from a societal perspective, future studies need to collect data on all relevant costs generated by patients suffering from exacerbations.

COSTS AND CHARGES

Estimates can be presented as charges based on official list prices or costs based on actual resource use. Studies need to move away from using charge data based on official list prices towards measuring costs based on actual resource use. This is because, for instance, charges for treating COPD exacerbations in hospital may not accurately reflect actual expenditure on administration, billing, capital depreciation, maintenance, laundry and other hospital services. Alternatively, in studies that measure charges, these need to be converted into costs by means of cost-to-charge ratios. Such adjustment by cost-to-charge ratios is regularly used in cost studies set in the United States.

CONCLUSIONS

COPD exacerbations impose a considerable economic burden on patients, the health care system and society. The high burden originates from difficulties involved in diagnosing the disease, expensive treatments, the chronic nature of COPD exacerbations, and the indirect costs associated with reduced ability to work. Increasing awareness of the disease, improving diagnostic strategies, and providing evidence-based health care are crucial steps in reducing the morbidity, health care expenditure and lost productivity associated with COPD exacerbations. The substantial economic burden underlines the need for further research into cost-effective approaches to diagnosing and treating COPD exacerbations.

Declaration of interest

The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.