ABSTRACT
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.
Subject(s)
Pulmonary Disease, Chronic Obstructive/physiopathology , Adrenal Cortex Hormones/therapeutic use , Aged , Anti-Bacterial Agents/therapeutic use , Bulgaria , Cohort Studies , Disease Progression , Female , Hospitalization , Humans , Male , Middle Aged , Phenotype , Prospective Studies , Pulmonary Disease, Chronic Obstructive/drug therapy , Pulmonary Disease, Chronic Obstructive/therapy , Risk Factors , Time FactorsABSTRACT
BACKGROUND: Environmental pollution can be one of the main risk factors for acute exacerbations of chronic obstructive pulmonary disease (COPD). AIM: To study the relationship between air pollution, outdoor temperature and exacerbations of COPD. MATERIALS AND METHODS: COPD patients (n=1432) were followed up for one year. The levels of particulate matter up to 10 µm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2) and outside temperatures were collected from the Environmental Agency database. RESULTS: A total of 309 acute COPD exacerbations (AECOPD) were recorded in the analysis. The daily mean concentrations of PM10 were found to correlate significantly with the daily mean concentrations of NO2 and SO2 (ρ 0.34 and ρ 0.49, respectively; p=0.0001). The negative correlations between the daily mean temperature and the daily mean levels of PM10, NO2 and SO2 were also significant (ρ -0.44, ρ -0.11, and ρ -0.37, respectively; p=0.0001). The daily number of AECOPD correlated with the mean levels of PM10 in the previous six days (ρ 0.14; p=0.02) and the lower outdoor temperature (ρ -0.2; p=0.001). The negative correlation between the daily number of AECOPD and the mean daily temperature was stronger in days with levels of PM10 above 50 µg/m3 (ρ -0.3 p=0.02 vs. ρ -0.18 p= 0.01). CONCLUSION: Lower daily mean temperatures were associated with the levels of air pollutants. The level of PM10 correlated with the levels of the other air pollutants. The daily number of AECOPD was found to correlate weakly, but signifi cantly with the mean level of PM10 in the previous six days.
