[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.
Liu
Chun-tao
CT
Department of Respirology, Huaxi Hospital, Sichuan University, Chengdu 610041, China.
Wang
Ya-min
YM
Wang
Gang
G
Tan
Cheng-wu
CW
Pang
Ya-min
YM
D000293:Adolescent; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D000730:Androstadienes / Q000008:administration & dosage / Q000009:adverse effects; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000517:prevention & control*; D004359:Drug Therapy, Combination; D005260:Female; D000068298:Fluticasone; D006801:Humans; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests; D000068299:Salmeterol Xinafoate; D055815:Young Adult
D000730:Androstadienes; D018927:Anti-Asthmatic Agents; D000068299:Salmeterol Xinafoate; D000068298:Fluticasone; D000420:Albuterol