AT THE ERS CONGRESS 2016
LONDON (FRONTLINE MEDICAL NEWS) – A study comparing patient data with six definitions of the Asthma-COPD Overlap Syndrome (ACOS) found only one of the patients analyzed met all definitions. This provoked an animated discussion at the annual congress of the European Respiratory Society about the utility of ACOS as a clinical entity.
Of 864 patients diagnosed with chronic obstructive pulmonary disease (COPD) or asthma drawn from the Netherlands Epidemiology of Obesity cohort (a population-based study with 5,784 patients), 39.1% (338 patients) met at least one of the definitions of ACOS, while 0.1% (one patient) met the criteria for all six definitions.
When this finding was presented, the ERS audience first laughed and then applauded. At the end of the presentation, long lines formed at the microphones. Every comment made was hostile to the concept of ACOS.
“Let us bring ACOS to an honorable death,” said one audience member. His point, reiterated by all who commented subsequently, was that ACOS confuses efforts to treat the underlying respiratory symptoms. Even in those who have both asthma and COPD, the speaker, like other members of the audience, said he considered the diagnosis of ACOS unhelpful.
The six definitions in the study included the latest and just published consensus definition from the ERS ( Eur Respir J. 2016;48[3]:664-73 ). According to the ERS definition, the key features of ACOS are age greater than 40 years, long-term history of asthma (since childhood or early adulthood), and significant exposure to cigarette or biomass smoke.
The other definitions analyzed included a medical history of both asthma and COPD, a self-reported history of both asthma and COPD, and a record of the proportion of a person’s vital capacity that he/she is able to expire in 1 second of forced expiration of less than 0.7 plus a record of fractionated nitric oxide concentration in exhaled breath of greater than or equal to 45 parts per billion.
Although attempted, a Venn diagram that would show overlapping subsets of patients that fell into these definitions “was not possible,” according to Tobias Bonten, MD, University of Leiden, the Netherlands.
Asthma duration was just over 10 years in those identified as having ACOS by medical history alone (registry-based definitions), just over 20 years in those with a medical history and objective evidence of impaired lung function, but about 40 years in those with a self-report of both asthma and COPD.
One area that all groups created by the ACOS definitions did have in common was demographic variables, such as median age, proportion of patients defined as overweight or obese by body mass index, and proportion who were current smokers.
Members of the audience acknowledged the importance of considering the coexistence of asthma and COPD, but expressed skepticism about the value of ACOS as a separate entity in the clinic.
“ACOS is something like the emperor’s new clothes,” one audience member said during the discussion. “It is important to identify asthma patients with obstruction because they have reduced lung function that should be treated more actively, but I find the definition [of ACOS] unnecessary,” he said.
A similar conclusion was drawn in a review article devoted to ACOS published last year ( N Engl J Med. 2015;373[13]:1241-9 ). “It is premature to recommend the designation of ACOS as a disease entity,” the authors wrote.
This is a position widely shared by clinicians, judging from audience comments provoked by this demonstration.
For the sake of time, the moderators were forced to end the discussion with significant lines of clinicians at the microphone.
“It is quite clear that ACOS should die,” said one of the last speakers given a chance to voice an opinion. He suggested that the coexistence of asthma and COPD is something that “quite clearly can happen,” but he objected to definitions he said are unhelpful for clinical care.
Dr. Bonten reported no relevant financial relationships.
