[A study on a therapeutic protocol to improve the control of persistent asthma by monitoring sputum eosinophil counts]

Abstract

Objective: To evaluate the clinical applicability of a therapeutic protocol aiming to improve the control of asthma by reducing the eosinophil (EOS) counts in induced sputum.

Methods: A prospective, randomized and controlled study was conducted from February 2005 to February 2006. Forty-one patients with persistent asthma in the outpatient clinic were enrolled and randomly allocated to management groups either by minimization of the induced sputum EOS (Group A, n = 20) or by standard clinical guidelines (Group B, n = 21). The baseline data were collected after a 2-week run-in period. The doses of inhaled or oral glucocorticoids were adjusted according to sputum EOS count (Group A) or according to symptoms and lung functions (Group B). The patients were followed up for a total of 6 months, during which the patients were assessed for 4 times, at day 15, and at the end of the 2(nd), 4(th) and 6(th) month. Sputum induction and EOS counts were performed at the 2(nd), 3(rd) and 4(th) visits. The primary result was the total number of acute exacerbations. Rescue use of short-acting beta(2)-agonists, symptom scores, lung functions, use of glucocorticoids, and the number of sputum EOS counts were also compared between the groups.

Results: In a study period of 6 months, the total numbers of acute exacerbations in Group A and Group B were 11 and 26 respectively, the difference being significant (t = 6.34, P = 0.026). beta(2)-agonist use, symptom score, PEF variability, FEV(1), and the average daily dose of inhaled glucocorticoids were not different between the two groups at any visits. The sputum EOS percentage at baseline and at the end of study in Group A was 0.067 (0.015, 0.169) and 0.048 (0.015, 0.150) respectively, the decrease being significant (F = 3.39, P = 0.02), but in Group B was 0.040 (0.014, 0.133) and 0.045 (0.012, 0.236) respectively (F = 1.07, P = 0.37).

Conclusion: A treatment strategy directed at reducing the number of the induced sputum EOS count is clinically feasible and effective for the adjustment of glucocorticoids and therefore for a better control of asthma.