DENVER – Exacerbations of chronic obstructive pulmonary disease show distinctly different temporal patterns of onset and resolution, which may have implications for treatment and prognosis, researchers reported.
In a prospective cohort study among patients with COPD who kept daily diaries for at least 2 years, 56% of exacerbations started suddenly; the rest began gradually.
Dr. Gavin C. Donaldson
The sudden-onset type were 18% shorter in duration than were the gradual-onset type, reported presenting author Gavin C. Donaldson, Ph.D., a senior lecturer and respiratory medicine specialist at the University College London.
The nature of onset of an exacerbation "is of particular interest because it is the prodrome that is reported to the physician when the patient comes into the clinic and dictates the courses of therapy that they receive," he noted at the International Conference of the American Thoracic Society. Hence, a better understanding of these events could help physicians to time therapy more appropriately, to patient benefit.
Study results additionally showed that patients frequently had episodes of symptom worsening that resolved without ever turning into exacerbations.
"We have all had this concept of ‘a patient is either exacerbating or is stable,’ " Dr. Donaldson commented. "There is increasing evidence coming out that patients actually fluctuate around a level which is not clinically significant, and we are finding that these sorts of symptom episodes are really part of that fluctuation. They are not particularly clinically important [that is, the patient doesn’t report it], but it may be important in terms of their disease progression."
Patients participating in the London COPD study recorded peak flow readings and various symptoms – including major (dyspnea, sputum purulence, and sputum volume) and minor (nasal discharge/congestion, wheeze, sore throat, and cough) symptoms – on a daily basis.
The investigators used the diary data to identify episodes of worsening symptoms and to identify exacerbations (defined according to standard criteria as requiring an increase in at least two symptoms, one of them major, on 2 consecutive days).
Results were based on 212 patients who had an average age of 68 years. In all, 64% were men, and 33% were current smokers. Their FEV1 (forced expiratory volume in 1 second) was 45% of that predicted.
All patients had at least 2 years of follow-up, and the total follow-up for the cohort was 890 patient-years.
The patients experienced 4,439 episodes of worsening symptoms, slightly more than half of which resolved spontaneously and the rest of which resulted in a defined COPD exacerbation. The median number of exacerbations was 2.33 per patient per year.
Analyses revealed two distinct patterns of exacerbation onset, according to Dr. Donaldson. With the sudden-onset pattern (seen in 56%), the median time between initial worsening of symptoms and exacerbation was 0 days. With the gradual-onset pattern (seen in 44%), the time to exacerbation was 4 days.
In addition, the time between the start of an exacerbation and recovery to baseline health status was a significant 18% shorter for sudden-onset vs. gradual-onset exacerbations (11 days vs. 13 days; P less than .001).
The treatments that patients received did not seem to affect these onset or recovery patterns, he noted. If anything, there was a greater tendency for treatment in the exacerbations that went on longer.
Multiple logistic regression analyses showed that certain factors predicted the nature of onset and recovery, according to Dr. Donaldson. Exacerbations were more likely to have a sudden onset in patients who were current smokers (odds ratio, 1.28), had cold symptoms (OR, 1.27), and – especially – had purulent sputum at the time (OR, 13.47). There was less likelihood of a sudden onset in patients with a higher body mass index (OR, 0.98) or cardiovascular disease (OR, 0.78), or if the exacerbations occurred during the spring (OR, 0.71).
Exacerbations were more likely to have a long recovery time (defined as recovery taking more than 12 days) if they had a gradual onset (OR, 1.39) and also if patients were male (OR, 1.27) or had cold symptoms (OR, 1.30), and if they occurred in the winter (OR, 1.36). There was less likelihood of a long recovery time in patients having purulent sputum (OR, 0.91).
Dr. Donaldson did not report any relevant conflicts of interest.