The continuing discrepancy between national and international guidance is unhelpful for patients, doctors, policy makers, and researchers because the Global initiative for chronic Obstructive Lung Disease (GOLD) does not require the presence of subjective symptoms (cough, sputum production, shortness of breath), whereas NICE guidance states that symptoms are a requirement for diagnosis and classification of chronic obstructive pulmonary disease (COPD).1 Why does the National Institute of Health and Clinical Excellence (NICE) persist with this discrepancy when there is substantial evidence that reported symptoms are unreliable for diagnosis?
For example, among 5000 people from those included in the Third National Health and Nutrition Examination Survey in the US, 70% of those with undiagnosed early airways obstruction, and up to 50% of undiagnosed stage 3 chronic obstructive pulmonary disease denied having cough or phlegm, and 40% denied a wheeze.1 A longitudinal study of over 2000 patients with COPD, from 12 countries, found that ‘among subjects with severe airflow obstruction, a substantial proportion did not report symptoms’. About 40% of those in the GOLD severe category denied being breathless (modified MRC dyspnoea scale 0 [10%] or 1 [30%]).2 Likewise, among a large population survey in China of 20 000 people over 40 years of age, 8% were found to have COPD of whom 35% had no symptoms (they said ‘no’ to the questions: ‘do you have cough, phlegm, wheeze, or breathlessness?’).3
In the UK, there are a total of over 800 000 (prevalence 1.5%) people on general practice COPD registers (Quality and Outcomes Framework data).4 However, cross-sectional studies and extrapolation of data indicate that the actual prevalence should be nearer to 4%. More than half of the people with COPD are currently not identified.5,6 The main conclusion is that symptoms are unreliable and the availability of spirometry for all those at risk remains the only way to identify those missing millions.
Until NICE comes fully into line within criteria for diagnosis and is prepared to ignore unreliable subjective symptom scoring, then these figures are unlikely to improve and a state of confusion and uncertainty will remain.
- © British Journal of General Practice, April 2011