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(Chest. 2003;123:784-791.)
© 2003 American College of Chest Physicians

Costs of Chronic Bronchitis and COPD*

A 1-Year Follow-up Study

Marc Miravitlles, MD; Cristina Murio, MD; Tina Guerrero, BSt and Ramon Gisbert, PhD; on behalf of the DAFNE Study Group

* From the Servei de Pneumologia (Dr. Miravitlles), Institut Clínic de Pneumologia i Cirurgia Toràcica (IDIBAPS), Hospital Clínic i Provincial, Barcelona; Unidad de Pneumologia (Dr. Murio), Hospital General Sant Cugat del Vallés; Pharma Research (Ms. Guerrero), Division of Pharma Consult Services S.A., Barcelona; and SOIKOS S.L. (Dr. Gisbert), Barcelona, Spain.

Correspondence to: Marc Miravitlles, MD, Servei de Pneumologia, Hospital Clínic i Provincial, Villarroel 170 (UVIR, esc 2, planta 3), 08036 Barcelona, Spain; e-mail: marcm{at}separ.es


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Objective: This study attempted to determine the total direct costs derived from the management of chronic bronchitis and COPD in an ambulatory setting through a prospective, 1-year, follow-up study.

Method: A total of 1,510 patients with chronic bronchitis and COPD were recruited from 268 general practices located throughout Spain. Patients were followed up for 1 year. All direct medical costs incurred by the cohort and related to their respiratory disease were quantified. Costs were calculated for patients with confirmed COPD according to the degree of severity of airflow obstruction.

Results: The global mean direct yearly cost of chronic bronchitis and COPD was $1,876. The cost generated by patients with COPD was $1,760, but the cost of severe COPD ($2,911) was almost double that of mild COPD ($1,484). Hospitalization costs represented 43.8% of costs, drug acquisition costs were 40.8%, and clinic visits and diagnostic tests represented only 15.4% of costs.

Conclusion: This is the first prospective follow-up study on a large cohort of patients with chronic bronchitis and COPD aimed at quantifying direct medical costs under usual clinical practice in the community. Costs of chronic bronchitis and COPD were almost twofold those reported for asthma. Patterns of COPD management in the community differ from those recommended in guidelines. COPD represents a great health-care burden in developed countries, and aging of the population and continuing smoking habits predict that it will continue to do so in the future.

Key Words: chronic bronchitis • COPD • cost • pharmacoeconomics • primary care • treatment primary care


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
COPD constitutes an important health problem in developed countries. In Spain, 9% of adults between 40 years and 70 years of age have COPD, although only 22% of cases are diagnosed.1 2 Tobacco smoking is the main etiologic factor for COPD. In a population-based study, 25% of the population between 40 years and 70 years of age were smokers and another 25% were former smokers.3 Smokers with COPD had higher tobacco consumption and greater dependence on nicotine, and more than one third had never tried to stop smoking.3 These data indicate that the problem of COPD will continue to grow in the near future.

COPD is a frequent cause of hospitalizations, disability, and death, and generates a great social and economic burden. The economic impact of COPD in 1993 was estimated to be more than $15.5 billion in the United States, with $6.1 billion for hospitalization.4 Nevertheless, pharmacoeconomic studies on COPD have only recently appeared in the medical literature; most of these studies are estimates based on administrative and population data and use a prevalence-based cost-of-illness approach,5 6 7 8 others use data from health-care databases,9 and one study10 identified a group of patients with COPD from medical records and quantified retrospectively the use of medical resources in recent years. Results of these studies vary greatly, from a yearly direct medical cost of chronic bronchitis of $8167 to $10,812 for a patient with severe COPD.10 However, there is a paucity of prospective studies aimed at quantifying the direct medical costs incurred by patients with chronic bronchitis or COPD in the community.

The aim of this study was to determine prospectively the total direct medical costs associated with the management of patients with chronic bronchitis and COPD under current medical practice. For this purpose, we followed up over 1 year a cohort of patients with well-characterized chronic bronchitis and COPD recruited in a multicenter study on acute exacerbations in primary care in Spain.11 12


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Study Design
This pharmacoeconomic analysis was conducted with data derived from the follow-up of a cohort of patients included in a study on acute exacerbations of chronic bronchitis and COPD. Full details of the study methodology and patient selection are presented elsewhere.11 12 A brief summary of the design is presented here. Two thousand four hundred fourteen patients with a diagnosis of chronic bronchitis consistent with American Thoracic Society (ATS) recommendations13 were initially recruited. Exclusion criteria included diagnosed cystic fibrosis, asthma, severe bronchiectasis, or life expectancy from nonrespiratory diseases < 2 years.

Patients were characterized as far as possible; although spirometry is not readily available in primary care in Spain, as in many other countries,14 15 spirometric data could be collected from a significant sample of patients. Eligible subjects with COPD had a maximum ratio of FEV1/FVC < 0.7 and a maximum FEV1 <= 80% of predicted. Since chronic bronchitis is defined on clinical grounds, patients without spirometric values, but with ATS criteria of chronic bronchitis, were included in the study. However, comparison of demographic, clinical, and evolution variables between patients with pulmonary function tests (PFTs) [demonstrated COPD cases] and patients without PFTs was made to test the hypothesis that both groups were of similar characteristics. Thus, for the purpose of the study, ie, evaluation of costs of chronic bronchitis over 1 year, all patients were studied together. Patients with spirometric criteria of COPD provided information on costs of COPD, and FEV1 (percentage) values were used to classify them into different degrees of severity (mild, moderate, or severe) according to cutoff values proposed by the ATS guidelines13 as follows: stage I, FEV1 > 49% of the predicted value; stage II, FEV1 35 to 49% of the predicted value; and stage III, FEV1 < 35% of the predicted value. Predicted FEV1 values were taken from a sample of Mediterranean subjects.16

The study consisted of two phases. The first attempted to investigate the evolution and costs associated with ambulatory treatment of acute exacerbations of chronic bronchitis and COPD. Results of the first phase have recently been published.11 12 The second phase comprised the prospective 1-year follow-up of the cohort of patients with the aim of identifying the direct medical costs generated by a well-characterized population of chronic bronchitis and COPD patients followed up in primary care under usual medical practice. The results of this second phase are presented herein.

To evaluate the direct medical costs, patients were scheduled to visit the corresponding physician on two occasions: at 6 months (visit 1) and at 12 months (visit 2). During both visits, information was collected on usual intake of respiratory drugs, diagnostic tests, and medical visits generated by their respiratory disease. Patients were instructed to attend unscheduled visits in cases of an increase in symptoms as they used to do before initiation of the study.

Since this was an observational study aimed at identifying current practice and costs associated with usual medical care and not under experimental conditions, treatment of chronic bronchitis and COPD, either in stable phase or during exacerbations, was left to the criteria of the attending physician. This study complied with the Spanish legislation on observational studies. Patients’ data were coded at inclusion in the database to preserve confidentiality.

Cost Analysis
Costs in this analysis were identified for drugs, oxygen therapy, outpatient visits, emergency department visits, hospitalizations, and admissions to ICUs. Costs of laboratory tests, diagnostic tests, and procedures performed during the study were also registered. Expenditures were calculated in US dollars (exchange rate at the time of the study, 168 Spanish pesetas per $1). Acquisition costs of pulmonary drug therapy were based on the official registered price.17 Average wholesale prices were based on the actual product and dose regimen used. Continuous oxygen therapy cost was estimated to be $5.7/d.

Costs per outpatient visit, emergency department visit, and hospitalization were estimated using data from the SOIKOS health database. This database was used for the pharmacoeconomic evaluation of acute exacerbations and has been described in detail elsewhere.12 All costs were updated to 2000 prices. Calculated costs are listed in Table 1 .


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  		Table 1.. Health-Care Resource Cost Estimates Used in the Study

 
Statistical Analysis
The Statistical Analysis Systems software package (version 6.08; SAS Institute; Cary, NC) was used for analysis of data. Mean values of quantitative variables for each group were compared by one-way analysis of variance. In cases of statistically significant differences, the Mann-Whitney U test was used for specific comparisons. Categorical variables were compared by the {chi}2 test. Since numbers of clinic visits and diagnostic tests were highly skewed, median values and ranges are also provided. The association of categorical independent variables with a higher direct cost of the disease was assessed by the {chi}2 test, and the significance of continuous variables was assessed with unpaired t test and Wilcoxon rank-sum tests. Variables were eligible for entry into a multiple logistic regression model if they were significantly associated with high cost at a p value < 0.25. The corresponding adjusted odds ratios (ORs) and 95% confidence interval (CI) limits were calculated for those variables in the model. A p value < 0.05 was considered significant.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Initially, 2,414 individuals with chronic bronchitis or COPD were recruited. Eighty-four patients (3.4%) required hospitalization for the first exacerbation and were subsequently followed up in the hospital; thus, they were not available for follow-up in primary care, leaving 2,330 patients available for the second phase of the study. A total of 1,510 patients (65%) completed the 12-month follow-up and formed the study population. No significant differences were observed between patients who completed the study and those unavailable for follow-up (Table 2 ). A total of 1,125 patients (74.3%) were men, with a mean age of 66.5 years (SD, 11.5 years). Spirometric results were available for 766 patients (50.7%), and mean FEV1 was 56.5% of predicted (SD, 16.3%). Demographic and clinical baseline characteristics of the patients and comparison between characteristics of patients with (known COPD cases) and without spirometry are summarized in Table 3 . Significant differences were observed only in the proportion of male patients; patients without spirometry were more frequently women (28.7% vs 22.4%; p = 0.012). Differences in other characteristics between patients with and without spirometry did not reach statistical significance.


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  		Table 2.. Baseline Characteristics of Patients Included in the Study*

 

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  		Table 3.. Characteristics of the Population Included in the Study*

 
Pulmonary drug therapy used in stable phase in the patients studied is described in Table 4 . Of note is the high proportion of patients receiving inhaled steroids (46.7%) compared with the low use of ipratropium (26.9%); almost one third of patients were regularly receiving mucolytics. In general, the use of the different drugs increased with the increasing severity of COPD, particularly steroids which were prescribed in inhaled form to 68.4% of severe cases and to 41.8% of mild cases. Oral steroids were administered to 20.3% of severe COPD in contrast to 4.5% of mild COPD.


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  		Table 4.. Percentage of Patients Receiving Different Types of Pulmonary Drug Therapy During the Study

 
The diagnostic tests and clinic visits generated by the cohort during the 1-year follow-up, as well as the mean and median number of procedures per patient, are displayed in Table 5 . Of interest, patients were twice as likely to undergo chest radiography or ECG, and three times as likely to undergo a basic blood analysis than forced spirometry.


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  		Table 5.. Number of Clinic Visits and Laboratory and Diagnostic Tests Generated by the Cohort of Patients With Chronic Bronchitis and COPD During 1 Year of Follow-up

 
The group had a mean of 1.9 acute exacerbations during 1 year and visited a general practitioner (GP) a mean of 5.1 times, whereas the number of visits to a chest physician, either ambulatory or hospital based, was less than one per patient per year. The mean number of emergency department visits was 0.5 per patient per year and hospitalizations were 0.2 per patient per year (Table 5) . All these data rose with increasing severity of the disease, with patients with severe COPD having a mean of 2.6 exacerbations per year, 0.6 emergency department visits, and 0.3 hospitalizations.

The global direct yearly cost of chronic bronchitis and COPD was $1,876. The cost generated by the patients with COPD was $1,760, but the cost of severe cases ($2,911 per year) was almost double that of mild cases ($1,484 per year), with moderate cases incurring intermediate costs (Table 6 ). These differences were specially manifested in hospitalization costs, while differences were smaller for clinic visits and diagnostic costs. For the group as a whole, hospitalization costs were the most important and represented 43.8% of total costs, followed by drug-acquisition costs (40.8%), and clinic visits and diagnostic tests represented only 15.4% of costs. These proportions changed slightly according to the severity of COPD; hospitalization costs were higher in severe cases (46.8%) than in moderate cases (38.9%) or mild cases (41.2%) [Table 6 ].


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  		Table 6.. Summary of Costs in US Dollars Incurred Over 1 Year and Stratified by Severity of COPD*

 
A regression model was constructed to identify baseline variables independently and significantly associated with high cost. High cost was defined arbitrarily as a cost > $1,500; this cost equals approximately the 75% percentile. Variables eligible for inclusion in the model (p value < 0.25) were as follows: age, spirometry (no/yes), number of exacerbations the previous year, smoking (nonex-smoker vs active), chronic heart failure, ischemic heart disease, use of theophyllines, oral steroids, long-acting ß2 agonists, ipratropium bromide, and inhaled steroids. Fifty-one patients were excluded from the model due to missing values, with a total of 1,459 patients being valid for analysis. The results of the regression model are presented in Table 7 . Chronic heart failure was strongly associated with higher cost (OR, 3.39; 95% CI, 2.33 to 4.95). Active smoking and frequent exacerbations in the past were also associated with higher cost (OR, 1.79; 95% CI, 1.34 to 2.39; and OR, 1.23; 95% CI, 1.15 to 1.31, respectively). Interestingly, having spirometry performed was inversely associated with cost (OR, 0.66; 95% CI, 0.51 to 0.86). The Hosmer-Lemeshow goodness-of-fit test indicated that the model was also well calibrated (p = 0.514), and the C statistics value was 0.76. In this test, a large p value indicates that the model is performing well, which means that there is no large discrepancy between observed and expected values.


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  		Table 7.. Variables in the Model for High Direct Medical Cost (> $1,500 per Patient per Year)

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
COPD represents a great health-care burden in developed countries. However, few studies have been aimed at quantifying the real burden of the disease. Most of these studies are estimates based on administrative and population data and use a prevalence-based cost-of-illness approach,5 6 7 8 others use data from health-care databases,9 and one study10 identified a group of patients with COPD from medical records and quantified retrospectively the use of medical resources in recent years. To our knowledge, this is the first follow-up study of a large cohort of patients with chronic bronchitis and COPD aimed at quantifying prospectively the direct medical costs incurred over 1 year under usual clinical practice.

Reference costs were obtained from a database containing information from > 350 different sources. Since this was a multicenter study, the use of such a database allowed us to minimize the problems derived from the variability of costs among centers, even in the same country. The cost of exacerbations was derived from the analysis of direct costs incurred by this cohort and published recently.12 The mean cost of the exacerbation was $159; however, we used the figure of $58.7 because it reflected the costs associated with the initial visit and treatment of the exacerbation. In the current study, repeated visits, emergency department visits, and ICU admissions were accounted for separately. Thus, if we had used the $159, we would have incurred double accountability, since this value also contains the proportional cost associated with failure.

The initial objective of the study was to determine the costs of a cohort of COPD patients in primary care. However, it must be taken into account that spirometry was not readily available for most GPs in Spain; only 35 to 45% of GPs request PFTs in patients with obstructive lung disease.18 19 In this context, we decided to include all patients with the diagnosis of chronic bronchitis to obtain the cost of chronic bronchitis, and evaluated separately those with spirometric criteria of COPD to obtain the costs of COPD, ruling out the possible bias due to the inclusion of milder cases with simple chronic bronchitis. In fact, from our results it can be concluded that most patients considered to have chronic bronchitis would have had COPD if appropriately assessed, since no significant baseline differences could be observed between them and the group with demonstrated COPD. Consequently, per patient yearly cost obtained for the global cohort, $1,876, was very similar to the cost of COPD patients, $1,760. Naturally, it is impossible to rule out the fact that some of our patients might have had asthma; however, a recent study in the United Kingdom observed that few cases of asthma were mistakenly diagnosed as COPD in primary care.20 In any event, a recent study5 that evaluated costs of asthma and COPD together reached the conclusion that for patients > 65 years old, only 4% of costs were caused by asthma, whereas in patients 15 to 25 years old, 91% of costs were attributed to asthma.5 Therefore, considering the age of our population, the possible misclassification (if it really existed) would have had a minimal impact on the results.

The present study permits extrapolation of the global burden of COPD. However, this extrapolation must be made with caution, since our population is not representative of the total population of COPD patients. From our results, we might be minimizing the costs of COPD, since our population consisted mainly of mild-to-moderate cases controlled in primary care (66.8% of our patients had stage I COPD) and the most severe cases controlled in tertiary hospitals were not included. With this limitation in mind, we can obtain an estimate of the cost of COPD in Spain. From a multicenter epidemiologic study, we know that 9% of the adult population between 40 years and 70 years of age have COPD.1 2 Based on official 1997 statistics, 13,645,000 people were found in this age group. Moreover, if we conservatively assume that the 9% prevalence is maintained beyond the age of 70 years, there would be a total of 1.7 million patients with COPD. Interestingly, this figure is very similar to the 1.5 million patients with COPD estimated to be in Spain in a model using tobacco consumption in the general population.21 However, only 22% of patients with COPD received a diagnosis and incurred direct medical costs.2 This leaves 270,000 patients, multiplied by $1,876, to obtain a total of $506.52 million, or $13.32 per capita. To put this into perspective, a study5 in the Netherlands obtained a cost for asthma and COPD of $23 per capita. Differences may be due to the inclusion of asthma in the latter study and a lower degree of underdiagnosis of the disease in the Netherlands compared to Spain, among others.

Drugs used for treatment of COPD accounted for 40.8% of total direct costs. Patterns of treatment recorded in the study did not follow current guidelines; as an example, 48.7% of patients were receiving inhaled corticosteroids, while only 29.8% were receiving the first-line bronchodilator ipratropium bromide. These results are similar to others obtained a few years earlier22 and highlight the importance of implementation of guidelines for correct use of drugs to minimize costs and optimize results based on the best scientific evidence available. In this respect, having spirometry was significantly associated with lower cost. Spirometry might be an indicator of a better pattern of management of the disease by GPs.

The yearly cost of $1,876 obtained in the present study lies somewhere in between published costs of COPD (Table 8 ). It is significantly higher than the $896 obtained by Wilson et al7 for COPD and also higher than the $1,341 for emphysema obtained in the same study as a result of an estimate of costs performed using national US data sources and published studies of prevalence and treatment outcome. It is also higher than the $813 in the study by Rutten-van Mölken et al5 in a prevalence-based estimate for the Netherlands. However, our costs are lower than those published by Hilleman et al10 in a retrospective study on a population of 413 COPD patients. In the latter work, patients with stage I COPD generated a cost of $1,681 compared to $1,484 in our cohort, stage II $5,037 compared to $2,047, and stage III $10,812 compared to $2,911. The reasons for these differences are multifactorial. First, they were studied in a population of COPD patients identified through hospital records, which implies more severity and complexity; as an example, up to 34% of their stage II patients and 76% of their stage III patients were receiving home oxygen, compared to only 11% and 25% of our patients, respectively. Furthermore, their stage III patients stayed a mean of 15 days per year in hospital, whereas ours spent a mean of only 2.4 days. Finally, differences were observed in reference prices, management practices, and health-care systems. In this respect, the price of medicines is somewhat lower in Spain than in similar countries; it should also be taken into account that medical fees in Spain are among the lowest in Europe. Thus, costs obtained in our study are probably lower than they would be in the United States. As a comparison, the cost of hospitalization for COPD was calculated to be $375 per day in the United States10 and $312 in Spain.


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  		Table 8.. Comparison of COPD Costs in Different Countries

 
To evaluate the costs according to severity of the disease, we used the ATS cutoff points.11 All cutoff points for the percentage of predicted FEV1 are arbitrary to some extent. A previous work evaluating the health-related quality of life of patients with COPD demonstrated that ATS cutoff points described the deterioration in health-related quality of life more accurately than the European Respiratory Society (ERS) system.23 We attempted to reproduce this data analysis for costs using the cutoff points proposed by the ATS, the ERS (70% and 50%),23 the British Thoracic Society, and the Spanish Society of Pneumology and Thoracic Surgery (60% and 40%)24 25 (Fig 1 ). Again, the ATS staging system described the progression of costs better than the ERS system, which showed almost no difference in costs between stages I and II. British Thoracic Society and Spanish Society of Pneumology and Thoracic Surgery classification offered intermediate results.



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  		Figure 1.. Direct medical costs of COPD in US dollars according to the degree of severity, and comparison of the classification of severity of different guidelines. BTS-SEPAR = British Thoracic Society and Spanish Society of Pneumology and Thoracic Surgery.

 
Another way of putting our results into perspective is to compare them with those obtained in patients with asthma. Traditionally, asthma has received more attention from researchers than COPD; however, the prevalence of COPD is higher than that of asthma and the burden of the disease may also be greater. In a study performed approximately at the same time in the same country (Spain), Serra-Batlles et al26 obtained direct medical costs of asthma from a population of 385 asthma patients recruited from either primary health-care centers or a general hospital. Their results showed the direct costs of asthma to be approximately half the costs of COPD obtained in our study, with an average cost of $885 per patient per year, ranging from $532 for mild asthma to $1,044 for moderate asthma, and to $1,276 for severe disease.

The present study has some limitations: our population may not be representative of all patients with chronic bronchitis or COPD, since patients were recruited from primary health-care centers. Therefore, severely affected patients may seek attention directly at a hospital or be followed up by chest physicians, and these patients could not be included in our study. However, 65% of patients ended the 1-year follow-up. This participation is not optimal; however, the difficulties faced in minimizing the losses in prospective follow-up studies in COPD must be emphasized. Furthermore, the demonstrated similarities between patients who completed the study and those unavailable for follow-up minimizes the possible bias introduced by nonparticipation.

In summary, patients with COPD controlled in primary care incurred a mean direct medical cost ranging from $1,484 for stage I to $2,911 for stage III. These costs are approximately double those of asthma. Hospitalization and drugs each represent > 40% of the costs, and clinic visits and diagnostic tests account for 15%. COPD represents a great health-care burden in developed countries, and aging of the population and continuing smoking habits permit us to anticipate that it will continue to do so in the future.


   Acknowledgements
 
The authors thank Irene Marimón, BSc, for monitoring the study, Christine O’Hara for manuscript editing, and the primary care physicians who provided information on their patients.


   Footnotes
 
Abbreviations: ATS = American Thoracic Society; CI = confidence interval; ERS = European Respiratory Society; GP = general practitioner; OR = odds ratio; PFT = pulmonary function test

The DAFNE Group (Decisiones sobre Antibioticoterapia y Farmacoeconomía en la EPOC) is funded by Mercl Farma y Química S.A.

Received for publication February 21, 2002. Accepted for publication September 4, 2002.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

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 Eur Respir JHome page
M. Hoogendoorn, M. P. M. H. Rutten-van Molken, R. T. Hoogenveen, M. L. L. van Genugten, A. S. Buist, E. F. M. Wouters, and T. L. Feenstra
A dynamic population model of disease progression in COPD
Eur. Respir. J., August 1, 2005; 26(2): 223 - 233.
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 ChestHome page
M. Alvarez-Mon, M. Miravitlles, J. Morera, L. Callol, and J. L. Alvarez-Sala
Treatment With the Immunomodulator AM3 Improves the Health-Related Quality of Life of Patients With COPD
Chest, April 1, 2005; 127(4): 1212 - 1218.
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 ThoraxHome page
M Decramer, R Gosselink, M Rutten-Van Molken, J Buffels, O Van Schayck, P-A Gevenois, R Pellegrino, E Derom, and W De Backer
Assessment of progression of COPD: report of a workshop held in Leuven, 11-12 March 2004
Thorax, April 1, 2005; 60(4): 335 - 342.
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 ChestHome page
N. Z. Tzovaras, V. N. Kouloumenta, K. I. Gourgoulianis, and J. Buffels
The Economic Impact of Late Detection of COPD in General Practice
Chest, January 1, 2005; 127(1): 412 - 413.
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 ChestHome page
M. Miravitlles and A. Torres
No More Equivalence Trials for Antibiotics in Exacerbations of COPD, Please
Chest, March 1, 2004; 125(3): 811 - 813.
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