ERS Statement: a core outcome set for clinical trials evaluating the management of chronic obstructive pulmonary disease (COPD) exacerbations

Plain English Summary

Sachin Ananth1

1West Hertfordshire Hospitals NHS Trust


Chronic obstructive pulmonary disease (COPD) is the third most common cause of death in the world. COPD exacerbations or flare-ups are when a patient’s symptoms get worse. This often leads to a short-term increase in medication use. Over 1 in 3 people with COPD suffer from exacerbations every year. Also, a severe exacerbation can cause a patient’s symptoms to be worse for the rest of their lives.

Treatment of COPD exacerbations has not changed for many years, and it could be improved. One of the reasons for this is that it is difficult to compare different treatments for COPD exacerbations. Treatments are tested in clinical trials, but the way they are tested can vary. One common difference between clinical trials are their outcomes, which is how the trial assesses if the treatment works. Outcomes need to be tested the same way in all trials. However, this does not happen.  For example, one trial of a drug may use death as the most important outcome, but another trial of the same drug may use going into hospital as its most important outcome. Therefore, it will be difficult to compare both trials, even though they are testing the same drug. Some trials may seem to use the same outcome, but they may use different definitions of this outcome. For example, one trial may define “improvement” of an exacerbation based on the patient’s symptoms, but another trial may define it based on their blood results. Not being able to compare clinical trials has meant that it is difficult to find new treatments for COPD exacerbations.

The European Respiratory Society (ERS) set up a group of doctors and COPD patients from around the world to solve this problem. The group, known as a task force, aimed to create a list of core outcomes. Core outcomes are a clearly defined list of results that are important to patients, doctors and researchers. They should be included in all clinical trials of COPD treatments. This will make it easier to compare different clinical trials in the future. The task force also created guidance about how to test each of these core outcomes.

First, the task force collected a list of all the different outcomes reported in previous COPD exacerbation clinical trials. Then, over 1,000 doctors and COPD patients from around the world completed a survey about which outcomes they think are most important. The task force then held two meetings to discuss the outcomes which scored highest in this survey. In the first meeting, the task force voted on the outcomes that the survey participants had recommended. If more than 7 out of every 10 people in the task force thought that an outcome was critically important, this outcome would be added to the final list of core outcomes. During the second meeting, the task force decided how each outcome should be defined and measured. This decision was based on previous studies, and the amount of time and resources needed for each definition. If more than 7 in every 10 people on the task force agreed on a definition for an outcome, then the task force would “strongly” recommend its use. If less than 7 in 10 people on the task force agreed on a definition, then the task force could recommend this definition, with a note that further research is needed to refine it.

The core outcomes that the task force recommended are listed in Box 1. The task force recommended that all future trials will use these outcomes. This will make it easier for doctors to understand the results of the trials, and to compare different trials.

If you want to learn more about this piece of research, you can read the full paper by clicking here.

Core Outcome Set for Clinical Trials Evaluating the Management of COPD Exacerbations. Outcomes strongly recommended by the task force are highlighted with a *


  • Death from any cause*
  • Death from a COPD exacerbation

Treatment success

Need for a higher level of care

  • Need for hospital admission for the presenting exacerbation
  • Need for admission to the intensive care unit for the exacerbation

Levels of oxygen and carbon dioxide in the blood (arterial blood gases)

Outcomes reported by patients

  • Breathlessness
  • Health-related quality of life (how a patient rates their current physical health)
  • Effect on activities of daily living (such as dressing and moving around the house)
  • Worsening of symptoms after the initial treatment

Future Impact

  • Disease progression (permanent change in the patient’s COPD severity after the exacerbation resolves)
  • Future exacerbations
  • Future hospital admissions


  • Serious adverse events of treatments*
  • Development of resistant bacteria
  • Development of pneumonia*

Treatment adherence*