Editorial |
Prevalence of COPD in primary care: no room for complacency
King's College London, Department of General Practice and Primary Care, 5 Lambeth Walk, London, UK; Email: patrick.white{at}kcl.ac.uk
Recognition of the challenge of chronic obstructive pulmonary disease (COPD) worldwide has accompanied significant advances in our understanding of it and its treatment.1,2 Smoking, the main cause of COPD, continues to grow as falling sales of cigarettes in the developed world are balanced by a bumper market in the developing world. Tobacco addiction, so difficult to combat even in highly developed health care systems, achieves a customer loyalty seen only in opiate users. The damage that smokers incur is reflected in rates of cancer and heart disease that accounted for a third of all deaths between the ages of 35 and 70 years in the US at the height of their smoking epidemic.3 In contrast with these mortality statistics, the place of COPD in the overall impact of smoking has been neglected until recently. COPD causes almost as many deaths as lung cancer in the UK, for example, but where death is caused by COPD, it is invariably the final episode in a story of relentlessly progressive disability. Belated realization of the health services cost of COPD which is the commonest cause of emergency admissions in the UK has contributed to its growing prominence.4 But COPD is even more important worldwide. It is the second leading and main smoking-related cause of death in China.5
Uncertainty about the true prevalence of COPD and widespread under-diagnosis have served to confuse and undermine public health efforts to raise its profile, improve detection and optimize treatment.6 In the UK, the prevalence of COPD is thought to be between 3% and 10% of the population.7,8 Yet the prevalence of diagnosed COPD reported by UK GPs within their new incentivized contract was only 1.5% in 2008, almost exactly the same as that reported by Soriano in 2000.9,10 Beyond smoking cessation, there is little evidence that early diagnosis can affect the outcome of COPD.11 But under-diagnosis is a significant problem even in patients with severe disease.12
The diagnosis of COPD requires effective spirometry, a challenge for primary care teams where the majority of COPD is diagnosed and treated.13,14 Paradoxically over-diagnosis rather than under-diagnosis is the main risk of poor quality spirometry. The effect is to add to the burden of primary care by failing to distinguish those who need treatment for their COPD from those whose disease is less severe than their inaccurate tests suggest or from those in whom COPD is not the cause of their symptoms.
Against this background, a dissonant chord is sounded by Gingter et al. in this issue of Family Practice.15 They suggest that the problem of COPD is significantly on the wane in Germany. They report a prevalence of COPD in general practice of 0.95% (30/3157) in patients aged 40 years or more or 6.9% (30/437) of smokers in that age group. This compares with a population prevalence in the UK of people diagnosed with COPD of 1.5%, equivalent to 3.8% of those aged 45 years and over, more than three times higher than Gingter et al. In a large survey in Sweden, the prevalence of COPD among smokers aged 40–60 years was 14%, more than twice that reported by Gingter et al. using the same Global Initiative for Chronic Obstructive Lung Disease criteria.1,16
Germany ranks eighth in smoking prevalence out of the 27 European Union States with 37% of its population aged 15 years and over reported to be smokers compared to 30% in France, 26% in the UK and 16% in Sweden.17 The report of a prevalence of COPD by Gingter et al. in Germany significantly less than that in countries with lower rates of smoking is perplexing and leads one to question whether the paper accurately estimates the population prevalence of COPD. Although the authors claim that their sample was representative of the population of Düsseldorf, no detail is given of the age and sex structure of the population from which the sample was drawn or of the sample itself and the relationship between them. Was there an over-representation of women as is common among primary care consulters? The prevalence of smoking was low at 17%, almost 25% lower than the expected prevalence of 22% quoted by the authors.18 Given potential design problems and in the absence of any comparison to previous studies of prevalence in Germany, the author’s conclusion that COPD is decreasing in Germany must be considered as lacking sufficient support.
There is no doubt that smoking-related diseases are falling among men in the developed world. Despite that there is more than enough evidence to convince the most sceptical observers that COPD is not only a significant continuing cause of morbidity and mortality, it is widely mis-diagnosed and under-diagnosed. Greater clarity is urgently required about the precise prevalence of COPD in all its grades of severity worldwide. We need to know the threshold of lung function below which treatment of COPD is likely to offer significant benefits to patients, the size of the risk smokers face of contracting COPD and the factors that predispose them to that risk. In the meantime, primary care clinicians in the developed world still under-estimate the seriousness of the challenge posed by COPD, and their complacency bodes ill for the response that is needed to meet this disease worldwide.
Notes
White P. Prevalence of COPD in primary care: no room for complacency. Family Practice 2009; 26: 1–2.
References
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12 Bednarek M, Gorecka D, Wielgomas J, et al. Smokers with airway obstruction are more likely to quit smoking. Thorax (2006) 61:869–873.
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18 Volzke H, Neuhauser H, Moebus S, et al. Regional disparities in smoking among adults in Germany. Deutches Artzeblatt (2006) 103:2784–2490.
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