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Spirometric screening for COPD: wishful thinking, not evidence
  1. Patrick White1
  1. 1Department of General Practice and Primary Care, King’s College London, 5 Lambeth Walk, London SE11 6SP, UK; patrick.white{at}kcl.ac.uk
  1. Michal Bednarek2,
  2. Dorota Gorecka2,
  3. Jan Zielinski2
  1. 22nd Department of Respiratory Medicine, National Research Institute of TB and Lung Diseases, 26 Plocka St, 01–138 Warsaw, Poland; m.bednarek{at}igichp.edu.pl

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The effect of spirometric screening on smoking cessation rates in the before and after study reported by Bednarek and colleagues1 is interpreted by the authors and, with reservations, in the accompanying editorial by Mannino2 as evidence to support the introduction of spirometric screening to detect early chronic obstructive pulmonary disease (COPD). This goes against the evidence of the study itself, and opposes the results of the comparative study of spirometric screening published by the same workers in 2004.3 Bednarek et al show an effect of spirometric screening in smokers with moderate or severe COPD (using 1995 European Respiratory Society criteria), but no effect in mild COPD despite the large numbers in their study. They repeat the findings of their earlier study, which is not mentioned in this paper by the authors themselves, nor is it mentioned by Mannino in his editorial. What is going on? Is there any significance in the fact that this work comes out of a programme entitled National Program of Early Detection and Prevention of COPD?4 What seems to be clear from this work is that there is no evidence that early detection leads to prevention in COPD.

In the first study Gorecka et al3 also claimed that their findings supported spirometric screening in mild disease. In fact they showed no effect overall, found evidence of an effect in a subgroup analysis of subjects with moderate or severe obstructive lung disease, and went on to make claims for the role of screening: “All smokers irrespective of their lung function tried to modify the habit as the result of screening for COPD combined with smoking cessation advice. The diagnosis of AL (airway limitation) motivated smokers to quit smoking.” Yet the results state unequivocally that there was no difference between smokers who had airflow limitation diagnosed and those who had normal lung function (NLF): “The one year cessation rate in smokers with AL was 10.8% versus 8.4% in smokers with NLF (NS).”

Why are these findings being interpreted over-optimistically as evidence of the value of screening for mild COPD? The most likely reason is wishful thinking, since the evidence suggests the opposite conclusion to that supported in the editorial by Mannino. Perhaps it simply arises from the frustrating recognition that COPD is common in adults but is predominantly undiagnosed.

There is a serious consequence from promoting early detection of COPD if there is no evidence that it makes any difference. Putting resources into spirometry for the early detection of COPD draws resources from more effective work, the most compelling of which in this context is general smoking cessation. In the study by Bednarek et al,1 71 people needed to be screened for every additional 1 year smoking quit achieved. This is equivalent to a cost of about €650 per additional smoking quitter.

Smoking cessation is the most important intervention in the primary and secondary prevention of COPD. It is equally important in the primary and secondary prevention of cardiovascular disease and many cancers including lung cancer. Until there is some definite advantage to be gained from the early detection of COPD in improving cessation rates among smokers, there is no justification for promoting spirometric screening for mild COPD as a separate public health strategy. On current evidence, screening to detect mild COPD is not warranted and will waste resources that would be better employed to promote smoking cessation in general.

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Authors’ reply

The World Health Organisation estimates that chronic obstructive pulmonary disease (COPD) affects 600 million people and that three million die every year from COPD. It is expected that, in 2020, COPD will be the third main cause of death worldwide.1 Until now these estimates have proved valid. This worrying situation calls for action.

In the National Program of Early Detection and Prevention of COPD in Poland, >90 000 “healthy” smokers aged 40 years or more performed spirometric tests. It was found that 20.3% of them had signs of airflow limitation compatible with a diagnosis of COPD, and 72% of these already had moderate or severe airflow limitation. None had previously consulted their family physician about their respiratory problems and most of them needed immediate further evaluation and treatment.2

By combining spirometric testing with antismoking advice, sustained quitting of smoking was achieved in 16% of the COPD group and 11% of the “healthy smoker” group.3 Similar results were obtained in the earlier pilot study based on a small group of subjects not included in the current study.4 These results are better than those obtained by general antismoking advice.5 The Lung Health Study confirmed that smoking cessation slows down the accelerated decline in forced expiratory volume in 1 s which occurs in patients with COPD with newly diagnosed disease. As many as 96.7% of subjects with moderate COPD who quit smoking still had moderate disease after 11 years of follow-up compared with 81.9% of those who continued to smoke. The initial success of quitting smoking in this group of patients turned out to be long lasting, with 93% still non-smokers after 11 years.6

Even if the cost of one additional person quitting smoking using our approach is €650, this is roughly half the cost of 1 year of treatment for one patient with COPD in the UK (US$1245).7 It is also equivalent to the cost of one life-year saved by antismoking advice only, which ranges from €385 to €797.8

Although there is a lack of evidence of benefit related to the early diagnosis of mild COPD by spirometric testing,9 this does not mean that such benefit does not exist. Fifty years ago systemic hypertension was frequently diagnosed when a patient had a stroke. Now early diagnosis and treatment of systemic hypertension are obligatory.

Early diagnosis of COPD defines a group of smokers at risk not only for the progression of COPD but also for lung cancer or ischaemic heart disease. Antismoking advice is an integral part of early diagnosis which will prevent many deaths from these diseases. For evidence of the benefits, we will have to wait.

References

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