Stability of Frequent Exacerbator Phenotype in Patients with Chronic Obstructive Pulmonary Disease

BACKGROUND: At present, there is little information in Bulgaria regarding the rate and stability of frequent-exacerbation phenotype in COPD patients. AIM: To study the rate and stability of frequent-exacerbation phenotype in COPD patients. MATERIALS AND METHODS: We followed up 465 COPD patients for exacerbations over a 3-year period. Exacerbations were defined as events that resulted in treatment with antibiotics and/or corticosteroids (moderate), or that led to hospitalization (severe). RESULT: Approximately 10% of the patients had two or more exacerbations per year (frequent-exacerbation phenotype), and this structure stayed stable over the study period. The exacerbation rate in the first year of follow up was 0.33 per stage I COPD patients (according to GOLD stages), 0.49 per stage II COPD patients; 0.69 - for stage III, and 1.06 for stage IV COPD patients. The frequent-exacerbation rate increased from stage I to stage IV by 4.35%, 9.17%, 10.79%, and 20.97%, respectively. A history of previous year exacerbations increased the risk of new exacerbations: with a history of one exacerbation - OR 2.1820 (95% CI: 1.4018 to 3.3965, p = 0.0005), and with a history of two exacerbations - OR 4.6460 (95% CI: 2.3286 to 9.2696; p < 0.0001). The frequent-exacerbation phenotype appeared to be unstable over the study period - up to 33% from those patients stayed in the phenotype for the next year. CONCLUSIONS: The exacerbation frequency and the rate of frequent-exacerbation phenotype increases with COPD progression. History of exacerbations in the previous year is a significant risk factor for exacerbations of COPD. The frequent-exacerbation phenotype appeared to be unstable over the study period. The pheno-type of non-exacerbators was more likely to remain stable over time.