Bronchial hyperresponsiveness as a predictor of treatment-response in COPD

Bronchial hyperresponsiveness (BHR) is an independent trait in COPD and provides important information on phenotype heterogeneity. Aim. To study bronchoprotective effect of 6-months tiotropium bromide (TB) and to compare of its clinical efficacy in COPD patients depending on a bronchial reactivity level. Methods. COPD symptoms, spirometry parameters and quality of life with use SGRQ were analyzed depending on the BHR in methacholine challenge at 29 COPD outpatients (GOLD II). Patients were divided two groups: the 1-st (n=15) provocative dose (PD)20≤0,471 mg and the 2-nd (n=14) PD20>0,471 mg. PD20 in the 1-st group was assessed initially and after 6-months in 24-26 hours last dose of TB. Results. BHR in the 1-st group was decreased at 6 months of therapy (p<0,05). In 6 months BHR was not revealed at 9 from 15 patients with initial BHR. In this group dyspnea decreased on 0,6 points, day and night cough was less on 1,0 and 0,6 points from baseline (p<0,05 in all cases). The correlation between dyspnea degree and PD20 was ρ=-0,67, p<0,05. Patients without BHR showed decrease only of a day cough (p<0,05). The mean pre-bronchodilator FEV1 increased on 240 ml from baseline in the 1-st group (p=0,007) and 72 ml in the 2-nd. No differences were found for post-bronchodilator FEV1. Exacerbations number in patients with BHR was characterized by decrease in comparison to the 2-nd group (p=0,03). Mean differences of SGRQ domains of group with BHR were 14-20 points from baseline (p<0,01). In the 2-nd group the only domain Symptoms showed improvement (p<0,05). Conclusion. TB reduces of bronchial reactivity level in the initial high values. COPD patients with BHR respond to TB therapy better than patients without BHR.