We did not show any correlations between the number of exacerbations, on the one side, and the individual components of the St. George’s Respiratory Questionnaire and pulmonary function tests, on the other side, in the patients at GOLD 1 and GOLD 4 stages. However we did find a number of correlations in the patients at GOLD 2 and GOLD s stages. In GOLD 2, the number of exacerbations correlated with symptoms (r = 0.33; p < 0.0001), impact of the disease on functional status (r = 0.34; p < 0.0001), and health status total score (r = 0.32; p = 0.0002) in St. George’s Respiratory Questionnaire, and with pre-bronchodilator vital capacity (VC) (r = −0.31; p = 0.0001), post-bronchodilator VC (r = −0.28; p = 0.0006), pre-bronchodilator forced expiratory volume in 1 s (FEV₁) (r = −0.2; p = 0.01), and post-bronchodilator FEV₁ (r = −0.22; p = 0.004) in pulmonary function tests. In GOLD 3, the number of exacerbations correlated with symptoms (r = 0.24; p = 0.01), activity (r = 0.32; p = 0.008), impact of the disease on functional status (r = 0.21; p = 0.03), and health status total score (r = 0.26; p = 0.0007) in St. George’s Respiratory Questionnaire as well as with the mMRC score (r = 0.21; p = 0.03).

An additional analysis was performed for patients with 0–1 exacerbation (n = 190; 72.8 %) and ≥2 exacerbations per year (n = 71; 27.2 %). The mean age was comparable in both groups. There were more women than men among those with ≥2 exacerbations per year (35.3 vs. 23.3 %, respectively; p <0.05). The mean FEV₁ was lower in those with ≥2 exacerbations than with 0–1 exacerbations per year (1.2 ± 0.5 L vs. 1.5 ± 0.6 L; p < 0.01; 46.3 ± 16.7 % predicted vs. 53.1 ± 18.5 % predicted; p < 0.01, respectively) (Table 2). No differences were found in the number of hospitalizations. There were more patients treated with inhaled steroids and theophylline in the group with ≥2 exacerbations per year. These patients also had higher scores in the quality of life domains in the St. George’s Respiratory Questionnaire (Table 3).

The number of self-reported exacerbations ranged from 0 to 8 per year. On Visit 1, 92 patients reported 1 exacerbation (62 % hospitalizations) and 5 patients reported 8 exacerbations (60 % hospitalizations). On Visit 2 after 12 months into the study, 73 patients reported 1 exacerbation (29 % hospitalization); the maximal number of 5 exacerbations was reported only by 1 patient (100 % hospitalizations). On Visit 3 after 24 months, 48 patients reported 1 exacerbation (35 % hospitalizations); the maximal number of 6 exacerbations was reported by 1 patient again (100 % hospitalizations). No significant differences in the quality of life score in the St. George’s Respiratory Questionnaire and the perception of dyspnea scale in the Medical Research Council Questionnaire were noted throughout the study period (Table 4).