[A clinical study on the significance of airway hyperresponsiveness monitoring in the adjustment of combined therapy for asthmatic patients].

Objective: To monitor the changes of symptom scores, airway hyperresponsiveness (AHR, represented by PC(35) sGaw), FEV(1)% and PEF% in patients with mild and moderate persistent asthma who received combined therapy of inhaled corticosteroids (ICS) and long-acting beta(2) agonists (LABA) and to evaluate the clinical significance of PC(35) sGaw and other parameters in guiding the adjustment of asthma stepwise therapy.
Methods: Patients with asthma were allocated randomly to group A (22 subjects), B (22 subjects), and C (21 subjects). The initial regimens for all patients in the first three months included ICS (fluticasone) plus LABA (salmeterol). For patients in group A, a fixed dosage was maintained for 18 months, while those in group B received tailored dosage or withdrawal of therapy according to the clinical control level (well or total control). The regimens for patients in group C included step-down or withdrawal according to PC(35) sGaw besides the clinical control. All subjects were followed-up for 18 months and the symptom scores, PC(35) sGaw, FEV(1)% and PEF% were measured and analyzed. The asthma clinical control levels of the three groups at end point were compared.
Results: A total of 65 subjects were enrolled and 46 completed the study. From the first to the third month after treatment, the symptom scores, FEV(1)% and PEF% improved significantly (t = 9.54, 13.17, 14.27, 12.4, 6.72, 6.59, 8.31, 5.22, and 5.96, respectively, all P < 0.01), and then maintained at relatively normal levels in a narrow range without significant progressive improvement during the later phases of the study. Meanwhile AHR declined abruptly in the first three months (t = 9.71, 12.04, and 14.31 in group A, B, C, respectively, all P < 0.01), followed by a slow but continuous improvement from the third to ninth month, and then maintained at a very low level. AHR disappeared in 4 cases but relapsed in 1 case after therapy withdrawal. The asthma clinical control level at the end point of group A, group B and group C were 93.3%, 53.3% and 93.8%, respectively (group A and group C versus group B, P < 0.01, respectively; group A versus group C, P > 0.05). There were fewer patients who underwent step-down therapy or withdrawal in group C compared to group B. However, patients in group C gained better asthma control and experienced less exacerbations compared to those in group B.
Conclusions: (1) Combined therapy with ICS plus LABA significantly improves symptoms, lung function and AHR of asthmatic patients. (2) Adjustment of therapy based only on clinical parameters may lead to early step-down or withdrawal and therefore asthma exacerbations. (3) PC(35) sGaw, an index of AHR, may be valuable in assessing asthma severity, evaluating the efficacy of treatment and guiding medication adjustment.