'Exacerbation-free time' to assess the impact of exacerbations in patients with chronic obstructive pulmonary disease (COPD): a prospective observational study

Abstract

COPD exacerbations are commonly quantified as rate per year. However, the total amount of time a patient suffers from exacerbations may be stronger related to his or her disease burden than just counting exacerbation episodes. In this study, we examined the relationship between exacerbation frequency and exacerbation-free time, and their associations with baseline characteristics and health-related quality of life. A total of 166 COPD patients reported symptom changes during 12 months. Symptom-defined exacerbation episodes were correlated to the number of exacerbation-free weeks per year. Analysis of covariance was used to examine the effects of baseline characteristics on annual exacerbation frequency and exacerbation-free weeks, Spearman’s rank correlations to examine associations between the two methods to express exacerbations and the Chronic Respiratory Questionnaire (CRQ). The correlation between exacerbation frequency and exacerbation-free weeks was −0.71 (p < 0.001). However, among frequent exacerbators (i.e., ≥3 exacerbations/year, n = 113) the correlation was weak (r = −0.25; p < 0.01). Smokers had less exacerbation-free weeks than non-smokers (β = −5.709, p < 0.05). More exacerbation-free weeks were related to better CRQ Total (r = 0.22, p < 0.05), Mastery (r = 0.22, p < 0.05), and Fatigue (r = 0.23, p < 0.05) scores, whereas no significant associations were found between exacerbation frequency and CRQ scores. In COPD patients with frequent exacerbations, there is substantial variation in exacerbation-free time. Exacerbation-free time may better reflect the burden of exacerbations in patients with COPD than exacerbation frequency does.

A Smart Mobile Health Tool Versus a Paper Action Plan to Support Self-Management of Chronic Obstructive Pulmonary Disease Exacerbations: Randomized Controlled Trial

“…The mean number of exacerbation-free weeks we found during the 1-year follow-up period was 30.6 weeks in the intervention group and 28.0 weeks in the control group. These mean values are in line with the 33.4 weeks that we found in a previous study in which we examined the relationship between exacerbation frequency and exacerbation-free time in a cohort of 166 COPD patients [21]. These values suggest that there was enough room for improvement as the participants seem to suffer from symptom worsening in approximately 20 weeks in the 1-year follow-up period.…”

“…In this study, we could not demonstrate positive effects on exacerbation-free weeks, exacerbation frequency, and health care utilization. Our primary outcome, exacerbation-free weeks , is directly related to exacerbation recovery time and may better reflect the burden of exacerbations in patients with COPD than exacerbation frequency does [21]. The mean number of exacerbation-free weeks we found during the 1-year follow-up period was 30.6 weeks in the intervention group and 28.0 weeks in the control group.…”

“…Our primary outcome was the difference in the number of exacerbation-free weeks between the intervention and control groups. An exacerbation-free week was defined as a week in which there had not been episodes of 2 or more consecutive days with worsening of 2 major symptoms (ie, dyspnea, sputum purulence, and sputum amount) or 1 major and 1 or more minor symptoms (ie, colds, wheeze, sore throat, and cough) [21]. Symptom changes were assessed using the Telephonic Exacerbation Assessment System (TEXAS, Radboudumc), an automated telephone call system that contacted participants weekly on the day and time of their preference [22].…”

Minimal Important and Detectable Differences of Respiratory Measures in Outpatients with AECOPD†

“…Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are frequent events during the course of COPD 1 . Recovery from AECOPD can take up to days, and it is known that some patients may never fully recover to their baseline status 2 .…”

<p>Effect of Erdosteine on COPD Exacerbations in COPD Patients with Moderate Airflow Limitation</p>

“…Time to first or subsequent exacerbation has been used as an outcome measure in some clinical trials 12,13. Moreover, determining exacerbation-free time is a useful way to assess the impact of exacerbations 14…”