3American Thoracic Society Workshop Report.Proceedings of the ATS workshop on refractory asthma:current understanding,recommendations,and unanswered questions.Am J Respir Crit Care Med,2000,162:2341-2351.
4Chung KF,Godard P,Adelroth E,et al.Difficult/therapyresistant asthma:the need for an integrated approach to define clinical phenotypes,evaluate risk factors,understand pathophysiology and find novel therapies.ERS Task Force on Difficult/Therapy-Resistant Asthma.European Respiratory Society.Eur Respir J,1999,13:1198-1208.
5ten Brinke A,Sterk PJ,Masclee AA,et al.Risk factors of frequent exacerbations in difficult-to-treat asthma.Eur Respir J,2005,26:812-818.
6Asthma Society of Canada. Asthma facts and statistics; 2012 [ R/ OL ]. [ 2014-03-01 ]. http://www, asthma, ca/corp/newsroom/ pdtVasthmastats, pdf.
7Masoli M, Fabian D, Holt S, et al. The global burden of asthma: executive summary of the GINA Dissemination Committee report [ J]. Allergy, 2004, 59: 468-478.
8Smith DH, Malone DC, Lawson KA, et al. A national estimate of the economic costs of asthma [ J ]. Am J Respir Crit Care Med, 1997, 156: 787-793.
9Ungar WJ, Coyte PC, Chapman KR, et al. The patient level cost of asthma in adults in south central Ontario. Pharmacy Medication Monitoring Program Advisory Board [ J]. Can Respir J, 1998, 5 : 463-471.
10Serra-Baflles J, Plaza V, Morej6n E, et al. Costs of asthma according to the degree of severity [ J]. Eur Respir J, 1998, 12: 1322-1326.