We searched Medline and Scopus up to March 19, 2009. We used the search terms “COPD” or “chronic obstructive pulmonary disease” in combination with “screening” or “spirometry”. We largely selected publications from the past 5 years but did not exclude frequently referenced and highly regarded older publications and reviews. The full list of references is available in the webappendix. We also searched the reference lists of articles identified by this search strategy and selected those we
ReviewScreening for and early detection of chronic obstructive pulmonary disease
Introduction
Chronic obstructive pulmonary disease (COPD) is projected to be the third leading cause of death by 2020.1, 2, 3, 4 Its prevalence and consequent burden is expected to rise with rapidly increasing smoking rates in developing countries. This risk factor combined with an ageing population accounts for the actual and forecasted rapid growth in COPD. Results from the landmark PLATINO (Proyecto LatinoAmericano de Investigación en Obstrucción Pulmonar)5 and BOLD (Burden of Lung Disease)6 studies indicate a higher prevalence of COPD than previously anticipated. Overall, the prevalence of COPD in the general population is estimated to be about 1% across all ages, rising steeply to 8–10% or higher in individuals aged 40 years or older.7 In population studies,5, 8, 9, 10 in which postbronchodilator spirometry was done and with information on previous diagnosis of COPD, findings show consistently that underdiagnosis of COPD is high and independent of overall prevalence (p=0·086), ranging from 72% in Madrid, Spain to 93% in Montevideo, Uruguay (figure 1). However, misdiagnosis is also frequent.11 These estimates of COPD underdiagnosis are substantially higher than those reported for high blood pressure, hypercholesterolaemia, and other similar disorders.
Potentially, COPD can be prevented at three levels (table 1). Primary prevention could be achieved by modification or reduction of the disease's main causal risk factor—cigarette smoking—or other known risk factors.11, 12 Secondary prevention could focus on screening or early detection of COPD, which generally entails spirometry, targeting of individual symptoms, or a combination. Tertiary prevention of COPD might include management of identified individuals with COPD to augment health status, reduce or slow disease progression, or diminish exacerbations and other adverse outcomes. Spirometry has a role in all three prevention levels.
Early diagnosis of COPD can be compared with screening programmes for hypertension and hyperlipidaemia. Initiatives targeting these conditions have greatly reduced deaths from acute myocardial infarction or stroke in the USA.13, 14, 15 To date, for COPD, such evidence is absent for general population improvements in lung function, reductions in exacerbations, or other disease outcomes and endpoints.16
Ongoing contentious issues in COPD research include definition and staging of the disorder. No consensus exists on how, when, and where spirometry and other methods should be implemented to screen for the disease, if at all. Here, we aim to summarise new developments and diagnostic techniques and provide an updated and balanced account of controversies and research needs with respect to COPD screening (table 1). We have paid particular attention to international differences in practice and presented the underlying ideas.
Section snippets
Spirometry
Spirometry is an important method for accurate diagnosis and effective management of chronic respiratory diseases, including asthma and COPD. Clinicians at primary17 and specialised respiratory18 levels agree that good quality spirometry should be used extensively if our aim is to reduce the burden of COPD to have a real effect on public health. As a diagnostic test, spirometry is a reliable, simple, non-invasive, safe, and non-expensive procedure for detection of airflow obstruction. This
Assessment of disease burden
Clinical COPD is associated with substantial underdiagnosis and misdiagnosis. Attempts to assess the burden of disease are typically thwarted by diagnostic issues. Such difficulties lead to an inaccurate view of the nature and causes of COPD because only a few instances of disease are seen by clinicians.23, 24 Estimates suggest that the proportion of smokers older than 40 years without a diagnosis of COPD but who actually have the disease is about one in five,17 and the proportion of
Case-finding versus a population approach
More than 25 years ago, Geoffrey Rose lectured on a general theoretical model of disease.27 Counterintuitively, he postulated that for any disease caused by a necessary agent within a population, the factors leading to this disease in individuals, and the determinants of incidence in the population, might differ. Corresponding strategies for control are the high-risk approach, which seeks to protect susceptible individuals, and the population approach, which aims to control the causes of
Individuals at risk of COPD
Other than tobacco smoking, risk factors for development of COPD are being increasingly recognised11 and include environmental factors such as occupational exposure to dust and fumes in developed and developing countries,29 and indoor biomass fuel burning in many developing countries.30 Reduction of such exposures on a population or individual basis might be worthwhile. Other environmental risk factors that seem unimportant for development of COPD but that might worsen disease include outdoor
Preclinical COPD
Specific criteria should be met before large-scale actions to detect a disease in its preclinical stage are undertaken. Three points for consideration are: (1) undetected disease would go on to cause substantial morbidity and mortality; (2) treatment of risk factors has a major effect on subsequent development of disease; and (3) an objective test that is simple, affordable, and safe is available to confirm the disease. COPD fulfils all these criteria.43 If smoking behaviour is amenable to
Established COPD
In the Lung Health Study,45 about 6000 patients with mild-to-moderate COPD (mean FEV1 78% of predicted) were studied prospectively from more than 70 000 current smokers aged 35–59 years; these participants were recruited by advertisements and offered a smoking-cessation programme. Around 25% of the total completely stopped smoking and 22% remained non-smokers to the end of study. Smokers and those who quit smoking were followed up for 5 years, with spirometric tests done every 12 months.
Clinical COPD
Identification of patients with symptomatic and clinically active COPD remains an important challenge. Many individuals will go to see their family doctor with symptoms but either the diagnosis of COPD will not be considered or they will be labelled as having smoker's cough or diagnosed with another disorder, such as a lower-respiratory tract infection or asthma. Individuals who do not consult a doctor might be in denial of their condition, view their symptoms as a health problem and not an
The Polish experience
High-risk population screening and COPD case-finding have been investigated and implemented in Poland. Free spirometry was offered in seven outpatient chest clinics to smokers older than 40 years.60 Of 11 027 individuals screened, 24% presented with signs of airflow obstruction. These researchers concluded that spirometry screening of smokers older than 40 years would probably detect many patients with airflow obstruction not diagnosed previously.
At the launch of a large national programme of
COPD screening issues
Surrounding COPD is an historical nihilism, with patients and even their doctors establishing blame and blatantly denying a medical problem exists. Recommendations on which individuals to screen for COPD, and when and how, differ at the primary and specialised care levels (figure 4).11, 17 If a full spirometry service is readily available, immediate diagnostic spirometry might be appropriate. In other settings, opportunistic case-identification spirometry could enable identification of
Prebronchodilator versus postbronchodilator values
All international COPD guidelines (apart from those of NICE) require postbronchodilator spirometry values. However, FEV1 and other respiratory indices obtained without bronchodilation are good markers of overall health.65 Guidelines and researchers' recommendations differ by how and when to do bronchodilation—eg, use of single or combined drugs with a range of doses (40–80 μg of ipratropium; 100, 200, or 400 μg of salbutamol; or a combination), or timing of procedures repeated from baseline
Local reference values
Globally, Hankinson's reference equations derived from NHANES III69 are used widely to calculate spirometry reference values according to age, sex, height, and ethnic origin. However, for most populations worldwide, unavailability of local reference values for estimation of predicted values,5, 6 and the largely unknown natural history of lung function and COPD, remain hurdles for accurate interpretation of individual spirometry data. A new Lung Function initiative aims to gather spirometry data
Quality control
By contrast with other laboratory and clinical tests, spirometry results need a clinical interpretation, with a minimum time commitment of 2–10 min. Interpretation of one value should be assessed in conjunction with many others and by review of the shape of the best curves (ie, flow-volume loops and timing).72 Indeed, selection of procedures, both prebronchodilator and postbronchodilator, can be quantified but is subject to arbitrary choice and cutoff values.18, 72
The best clinical pulmonary
Screening to aid smoking cessation
Simple brief advice from a health professional increases the chances of smoking cessation.74 Individuals with early lung damage who were also smokers were judged the group most at risk of accelerated deterioration of lung function compared with non-susceptible smokers or non-smokers.75 The effectiveness of any smoking-cessation strategy needs to be shown urgently. The difficulty in proving convincingly that biomedical risk assessments—such as measurement of exhaled carbon monoxide, genetic
Spirometry during follow-up
After a medical diagnosis of COPD, recommendations suggest that patients should undergo spirometry every 6 months or yearly. Spirometry done immediately after diagnosis will confirm (or should help to discard) the initial clinical impression and should help with tailoring of drug treatment and other interventions.11, 19 The finding of bronchiectasis or tuberculosis in individuals who smoke adds difficulty to the differential diagnosis of COPD, particularly in developing countries.79 In a
Innovations on questionnaires and technology
Continuous progress has been made with portable spirometers, and although difficulties with validation remain, some devices can display measured and predicted values, and lower limit of normal for FEV1, FVC, FEV1/FVC, peak expiratory flow, and others, and flow-volume and volume-time curves. Use of peak flow and a screening questionnaire to rule out severe COPD in population studies has been proposed.81 Several limitations remain for achievement of highly acceptable and reproducible spirometry
Spirometry away from the doctor's office
Spirometry undertaken at the primary-care level aims to exclude individuals with normal lung function and to identify those who need a complete investigation for COPD. In this context, spirometry protocols and standards in primary care will differ from those of specialised care, which aim to achieve a definitive diagnosis.83
Pilot tests are being done to investigate use of non-medical venues to implement spirometry. In particular, pharmacies might have some advantages. Findings showed that
Screening controversies
Some 40 years ago, cardiologists reported that high blood pressure, raised levels of cholesterol, physical inactivity, obesity, and tobacco smoking were major risk factors for cardiovascular disease. Appropriate large-scale screening and therapeutic programmes combined with encouragement of a healthy lifestyle were implemented on national levels. At that time, no evidence existed that those expensive initiatives would reduce morbidity and mortality from cardiovascular disease. However, a steady
Concluding remarks
If the medical profession does not take the early signs of COPD seriously, patients will probably continue to underestimate their condition. For those who smoke or frequently relapse, this attitude sends the wrong message, because we know that their disease will almost certainly progress with continued smoking. An important part of primary care relates to secondary prevention—ie, early detection of disease and monitoring of chronic illness. We have a professional duty to diagnose early and
Search strategy and selection criteria
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