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The Proceedings of the American Thoracic Society 6:704-706 (2009)
© 2009 The American Thoracic Society
doi: 10.1513/pats.200907-062DP
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Primary Prevention of Chronic Obstructive Pulmonary Disease in Primary Care

Thys van der Molen1 and Siebrig Schokker1

1 Department of General Practice, University Medical Center Groningen, University of Groningen, The Netherlands

Correspondence and requests should be addressed to T. van der Molen, M.D., Ph.D., Department of General Practice, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands. E-mail: t.van.der.molen{at}med.umcg.nl

ABSTRACT

Chronic obstructive pulmonary disease (COPD) is a prevalent disease, with cigarette smoking being the main risk factor. Prevention is crucial in the fight against COPD. Whereas primary prevention is targeted on whole populations, patient populations are the focus of primary care; therefore, prevention in this setting is mainly aimed at preventing further deterioration of the disease in patients who present with the first signs of disease (secondary prevention). Prevention of COPD in primary care requires detection of COPD at an early stage. An accurate definition of COPD is crucial in this identification process. The benefits of detecting new patients with COPD should be determined before recommending screening and case-finding programs in primary care. No evidence is available that screening by spirometry results in significant health gains. Effective treatment options in patients with mild disease are lacking. Smoking cessation is the cornerstone of COPD prevention. Because cigarette smoking is not only a major cause of COPD but is also a major cause of many other diseases, a decline in tobacco smoking would result in substantial health benefits.

Key Words: COPD • prevention • diagnosis • primary care

The prevalence and burden of chronic obstructive pulmonary disease (COPD) are recognized to be high, but accurate data on prevalence are lacking, and varying prevalence rates have been reported. This might be due to different interpretations of the definition of COPD. In the consensus report of the Global Initiative for Chronic Obstructive Lung Disease (GOLD), COPD is defined as a preventable and treatable disease with some significant extrapulmonary effects that may contribute to the severity of symptoms in individual patients. Its pulmonary component is characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles and gases (1). In a population-based study in which COPD was diagnosed based on the assessment of lung function by means of spirometry (GOLD stage II and higher), prevalences between 8.2 and 19.1% in adults 40 years of age or older have been found (2). In primary care, much lower estimates of the prevalence of physician-diagnosed COPD have been reported (between 1.5 and 3%) (3–5). A tip-of-the-iceberg phenomenon with many undetected patients—possibly in need for treatment—in primary care has been suggested to be responsible for this difference between estimates. Regarding this potential underdiagnosis and undertreatment, some important issues have to be emphasized.

DEFINING COPD

The definition of COPD is crucial (Figure 1). Although in the GOLD guidelines a broad definition of COPD is emphasized, many investigators focus only on the lung function component. In epidemiological research, a postbronchodilator FEV1/FVC ratio less than 0.70 is often considered as evidence of COPD. However, defining airway obstruction by the fixed 0.70 cut-off might result in misclassification. To reduce overdiagnosis in elderly patients and underdiagnosis in younger adult patients, the use of the lower limit of normal for FEV1/FVC has been recommended to define airway obstruction (6, 7). A clinical diagnosis based on symptoms, age, history of smoking, or contact with other pollutants is also emphasized in all guidelines. Because comorbidities are common, comorbidity should also be taken into account. The GOLD guidelines state that when asthma and COPD coexist, the asthma component prevails and should be treated. As a result of this definition of COPD, the population of interest (age > 45 years, airway obstruction, history of smoking, and no history of asthma) might be much smaller than estimated in many studies. In primary care, in The Netherlands and in most countries in Europe as well as in Canada and Australia, the majority of patients are individually known by their primary care provider (PCP). Because most patients stay enlisted to the same practice for a long time, the PCP is informed about all kinds of symptoms and diseases in the patient and his or her family. PCPs are therefore most likely to be aware of the presence of any kind of obstructive lung disease in individual patients. Due to trends in international consensus with regard to the diagnosis of these patients and the lack of recent spirometry data, a number of patients might be misclassified.


Figure 1
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  		Figure 1. Chronic obstructive pulmonary disease (COPD) definition and detection. LLN = lower limit of normal.

 
DETECTING PATIENTS WITH COPD

Using the narrow definition of COPD and excluding patients who already receive treatment, there still may be a considerable number of patients with undiagnosed COPD. Screening by means of spirometry might improve the detection of COPD in primary care. The potential benefits of screening have to be weighed against potential harms. Moreover, detecting a disease in an early stage does not automatically improve health outcomes. Screening is not worthwhile if no adequate treatments are available. This is crucial because the majority of effectiveness studies have not included patients with mild to moderate COPD. Indeed, there is evidence that therapy with bronchodilators—in particular with long-acting bronchodilators—improves quality of life in patients with mild to moderate COPD. Trials evaluating therapies in patients with airflow limitation who do not recognize or report symptoms have not been performed (8). Consequently, evidence that early detection and subsequent treatment leads to relevant health benefits in patients diagnosed with COPD is still lacking (8, 9). Nevertheless, several attempts have been made to detect patients using screening or case finding. Recently, Bednarek and colleagues performed a case-finding study in primary care using spirometry (10). A total of 1,960 patients over 40 years of age from a single primary care practice were investigated by means of a questionnaire, physical examination, and spirometry. This study revealed underdiagnosis of COPD in a primary care setting in Poland, where COPD was diagnosed in 183 patients (9.3%), of whom only 34 patients had already been diagnosed with COPD. Most patients identified with screening spirometry were diagnosed as having mild to moderate COPD. Nevertheless, the majority of these patients were symptomatic, suggesting that these patients might benefit from treatment. The effectiveness of treatment in patients who do not report symptoms has not been proven.

In another study by Van Schayck and colleagues (11), the effectiveness of case finding of patients at risk of developing COPD in primary care was investigated. Patients between 35 and 70 years of age who visited their doctor were randomly selected from two practices (approximately 10,400 patients were enlisted). Lung function was assessed by spirometry in smokers not using drugs for a pulmonary condition (n = 201). This study revealed airway obstruction (FEV1 < 80% of predicted) in 18% of patients. When smokers were preselected based on respiratory symptoms, in particular chronic cough, the percentage of patients with airway obstruction increased. Smokers with cough who were older than 60 years of age had a 48% chance of having airway obstruction. It is unknown how many of these patients had COPD and whether these patients benefited from the knowledge of their impaired pulmonary function. Our group screened a large primary care population by sending out 33,673 letters to patients (45–75 years of age) and inviting them to visit the practice to undergo spyrometry. Patients were asked to present themselves when they had smoked for more than 10 years. In total, 3,016 smokers or ex-smokers responded, of whom 1,049 had never undergone spirometry and were not known by their PCP to have a pulmonary disease. In 992 smokers or ex-smokers, spirometry data were collected successfully. Few patients were diagnosed as having moderate or severe COPD (Table 1), demonstrating that screening is likely to identify a predominance of patients with mild to moderate airway obstruction, bringing into question the benefits of such a procedure.


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  		TABLE 1. DIAGNOSIS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE ACCORDING TO GOLD STAGES (n = 992)

 
SMOKING CESSATION

Cigarette smoking is the most important risk factor for the development and progression of COPD. Smoking cessation is the single most effective intervention to reduce the risk of developing COPD and to stop its progression (1, 12, 13). If smokers who are informed about their spirometry results would be more motivated to quit smoking, screening or case finding by means of spirometry would be worthwhile. The evidence of spirometry as an independent motivational tool for smoking cessation is inconclusive (8, 14). Although recent studies suggest a positive influence of spirometry on smoking cessation rates (15, 16), definitive conclusions on the beneficial effect of spirometry cannot be drawn. Until more adequate studies testing the hypothesis that spirometry is effective in improving the success rate of smoking-cessation interventions are available, spirometry-based screening remains debatable.

Smoking harms nearly every organ in the body. Smoking, therefore, causes many diseases and reduces the health of smokers in general (17). The burden of smoking-attributable mortality is high. It is estimated that smoking results in more than 440,000 premature deaths each year in the United States. During 2000 to 2004, the three leading specific causes of smoking-attributable death were lung cancer (128,922 deaths), ischemic heart disease (126,005 deaths), and COPD (92,915 deaths). Smoking cessation should be advocated in all smokers.

CONCLUSIONS

Despite an overwhelming amount of research, data on the prevalence of COPD are incomplete and are based on different interpretations of the definition of COPD. Physiologically based definitions seem to overestimate the numbers. Clinician-diagnosed COPD prevalence is much lower and might underestimate the number of patients with COPD. Before screening to identify patients with COPD in primary care is considered, it should be clear how we define COPD. Guideline committees should be challenged to come up with practical definitions based on history, symptoms, and pulmonary function. Lack of evidence of effective therapy in patients with mild disease in GOLD stage I and II should be addressed when screening of COPD is advocated. Smoking cessation or prevention of smoking is the first preventive strategy for COPD and all other smoking-related diseases.

FOOTNOTES

Conflict of Interest Statement: T.v.d.M. has received reimbursement for serving on advisory boards with AstraZeneca ($10,001–$50,000), Boehringer Ingelheim ($5001–$10,000), GlaxoSmithKline ($10,001–$50,000), and MSD ($5001–$10,000). He has received honorarium for lectures with GlaxoSmithKline ($5,001–$10,000) and Nycomed ($10,001–$50,000) and has received funding for research from AstraZeneca ($100,001 or more) and MSD ($10,001–$50,000). He also receives royalties from MSD ($10,001–$50,000). S.S. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

(Received in original form July 11, 2009; accepted in final form August 20, 2009)

REFERENCES

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