Do not be too quick to discount chronic bronchitis symptoms and their association with the development of COPD, a UK expert has told delegates at the virtual American Thoracic Society 2020 conference.
Dr James Allinson, consultant respiratory physician at the Royal Brompton Hospital in London and honorary senior clinical lecturer at Imperial College London said despite the removal of GOLD grade 0 in the updated 2020 guidelines, chronic symptoms in some patients do reflect an increased chance of developing COPD.
He told the conference that GOLD 0 was meant to identify patients who did not have COPD but chronic symptoms such as chronic cough and sputum production that put them at risk.
Yet it was dropped because definitively linking chronic symptoms had proven difficult and studies such as the Copenhagen City Heart study not only found no link but that most cases developed in those who did not fall into the GOLD 0 category.
But that is not the end of the story, he argued, because the actual picture is more nuanced than a simple binary phenotype.
Age is the key factor, he said in his presentation, as well as persistence of symptoms.
Research has shown a clear link between chronic bronchitis and increased later risk of airflow limitation in the under 50s but not in those over 50, he said.
And data from the UK 1946 cohort shows a similar pattern in people in their 30s and 40s, where the prevalence of chronic sputum production increased among persistent smokers, with chronic symptoms identifying a heightened risk of airflow limitation by age 60.
“So it seems like something is happening in mid life and these ages are useful in terms of identifying increased risk,” he said.
In addition, it really appears that the greatest link with COPD development is among those who have persistent symptoms, he added.
“The course of symptoms over a long period of time seems to be important in how COPD develops.”
He added that data shows the longer that chronic sputum production is present the more FEV1 is lost. “Rather than being a binary phenotype this clinical marker seems to be a biomarker of developing and progressing disease.”
Dr Allinson told delegates that he hoped he had managed to convince them that for some individuals chromic bronchitis represents a step towards them reaching the threshold for diagnosis for COPD.
“During mid life these chronic symptoms do appear to reflect a heightened susceptibility to later COPD development and potentially an early phase of this development”.