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Early Diagnosis of CORD (Chronic Obstructive Respiratory Disease)

[Dr Kenneth Thomson] My last job in Northern Nigeria was, (with the help of 40 staff in strategic locations), to find, diagnose and treat up to 3,000 people a year infected with the parasite causing sleeping sickness, amongst a population of 13 million in the endemic area, before they knew there was anything wrong with them. The problem of CORD has similarities. The urgency is for early diagnosis by general practitioners before symptoms have developed. Up to half of lung function can be lost before a person is aware of anything wrong, and as many as 1 in 3 smokers is liable to develop CORD. Screening by spirometry. Ideally, all smokers should have their lung function tested by spirometry, even if they have only just begun to smoke, to establish their own baseline function. Over the years, further screening will show whether their function has reduced as expected with increasing age, or more than expected, which will suggest early chronic obstructive respiratory disease (CORD). It is unlikely there are enough spirometers in New Zealand, or qualified operators, to achieve this. In the meantime, anyone who has smoked a packet of 20 cigarettes a day for 10, or certainly for 20 years, should ask for a spirometry test. We all know that it can be exceedingly hard to give up smoking; but the probability that you will become a respiratory cripple in later life if you don’t give up, can be a wonderful incentive! Smoking cessation is the only way to reduce progression of early emphysema to CORD. The criteria for diagnosing CORD As with asthma, there is still no generally agreed, precise definition of CORD. A distinction from asthma is that the airway obstruction can only be slightly reversed, if at all, either spontaneously or by a reliever drug. The FEV1 (similar to peak flow) can never return to normal—in asthma it often does. CORD develops in patients with a variety of predisposing conditions, including emphysema, chronic bronchitis, asthma and bronchiectasis (abnormal widening of airways with liability to frequent infections and copious sputum). Hence the title of a Thorax editorial “The heterogeneity of COPD” (they prefer to call it “Chronic Obstructive Pulmonary Disease” [1]). Firm diagnosis — requires accurate spirometry, such as Kevin Baker, Good Health Wanganui’s Respiratory Resource Nurse and our Vice-President, can carry out at doctors’ surgeries on request. Repeated peak flow readings may be suggestive but are not decisive. The UK Guidelines suggest that COPD is present when l) The FEV1 is less than 80% of predicted normal for height and age, and 2) When another index, the FEV1/FVC ratio, is less than 70% of predicted normal. New evidence. However, a UK study of 110 patients who saw their general practitioners for acute exacerbations of COPD suggested that the first of these two criteria should be dropped2. The patients were fully investigated 2 months after recovery from their exacerbations. 30% of them had a normal FEV1 (i.e. over 80% of predicted value); nevertheless, the other index, (FEV1/FVC ratio) was below the 70% predicted in 41% of this group, and this is a ‘stand-alone’ criterion of obstructed airways. These 13 patients were clearly in an early stage of CORD; faced with the knowledge of what would happen if they did not stop smoking, there is a reasonable chance they would be able to overcome the addiction forthwith. “Heterogeneity” In this group of patients, 51% had emphysema; bronchiectasis was found in 29% by high resolution computed tomography “…an important finding of our study…”; they were clinically indistinguishable from the group as a whole. Only 5% of patients responded well to reliever drugs suggesting asthma as their main problem. Encouraging news for smokers who have not yet developed symptoms: “In individuals who have largely preclinical disease, the benefits of (smoking) cessation are clear and almost certainly lifesaving; these people simply will not get symptomatic COPD”.

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