Clinicians and patients can expect a future shake-up in the labels given to patients currently described as asthma or COPD or to patients with features of both diseases.
Baseline characteristics from the NOVEL observational longiTudinal studY (NOVELTY) have already demonstrated the marked heterogeneity within the diseases and considerable overlap between physician-assigned diagnoses of asthma and/or COPD.
NOVELTY, led by Australian Professor Helen Reddel, comprises more than 11,000 adults worldwide across the full spectrum of asthma and/or COPD.
One of the aims of the 3-year prospective observational study is to characterise patients according to their trajectories over the study period, for example whether their lung function was stable or declined, and to look back and see whether these groups could have been identified by their baseline characteristics or biomarkers.
Baseline data, published in the ERJ, show about half (52.8%) of patients had a physician-assigned diagnosis of asthma only, 12.4% asthma+COPD and 34.8% COPD only.
The study found no consistent differences in demographics such as BMI or smoking, across diagnosis/severity groups.
“Across the three diagnosis groups, mMRC dyspnoea grade, SGRQ total score and CAAT score were worse with greater physician-assessed severity, but there was marked variation within, and overlap between, each diagnosis and diagnosis/severity group,” the study said.
“Within each severity category, patients with asthma+COPD or COPD were more likely to have clinically important dyspnoea (mMRC grade ≥2), worse HRQoL and worse overall health status than those with asthma.”
The study also noted that while the proportions of patients with ≥1 or ≥2 exacerbations in the past 12 months increased across severity groups, they included 24.3% and 7.3% of patients with mild asthma and 20.4% and 5.3% of patients with mild COPD, respectively.
“Conversely, of patients assessed by the doctor as having severe asthma or severe COPD, 48.3% and 50.6%, respectively, were not reported to have had an exacerbation in the previous 12 months.”
There was also marked heterogeneity in lung function and in intensity of therapy observed across diagnosis and severity groups.
The study said the features typically used to define asthma and COPD in clinical trials and mechanistic studies were found across all sub-groups of patients.
“This indicates that the historical labels of “asthma‟ and “COPD‟ and the severity classifications used in clinical practice, do not identify clinically distinctive populations.”
“Our findings emphasise the need for a deeper understanding of phenotypes and endotypes of asthma and/or COPD, and challenge the specificity and utility of conventional classifications of “asthma‟ and “COPD”.”
Professor Reddel, from the Woolcock Institute of Medical Research, told the limbic that labels are still very important, particularly while mechanisms that contribute to specific risks are still being identified.
“I don’t believe you should throw out umbrella labels like asthma and COPD when they serve a useful purpose,” she said.
However she predicted that as with other conditions like breast cancer, many subtypes of respiratory disease would be identified.
“What has worked well in breast cancer is to identify a subset of patients where there is a clear treatment pathway.”
“We have highly personalised treatments for breast cancer but we also still talk about breast cancer as an entity because it is useful for lobbying and it is useful for patients because there are many problems that are common to all these subtypes,” she said.
“Taxonomy should always follow the identification of treatment. You don’t want to give a label to someone unless it means something.”
Professor Reddel said about 5-10% of people with asthma and about the same with COPD would satisfy the strict requirements for clinical trials in those conditions.
“The rest, which is 80-90%, may have features of both conditions. This is a group that needs to be investigated. It comprises multiple conditions with multiple underlying mechanisms but similar symptoms.”
“We‘ve got to be able to investigate the underlying mechanisms and work out which patients can be peeled off into a group that needs a specific treatment but at the same time keep people safe,” she said.
And she noted there were certainly indicators that people may not be getting the right treatment.
“For example, there are people who are labeled by their doctor as having mild asthma and clearly have a lot of exacerbations. If they have a lot of symptoms despite treatment, they either are not getting enough or they have got a mechanism that is not being addressed by the particular treatment.”
“We need to actually find the underlying mechanisms of specific clinical or physiological characteristics. Because someone can have a FEV1 of 60% predicted and it was 60% predicted 10 years ago. Someone else might have an FEV1 of 60% predicted and 10 years ago it was 80% predicted. Clearly we should not lump these groups together when we are seeking treatable mechansims.”