[1] Univ Ferrara, Res Ctr Asthma, I-44121 Ferrara, Italy
[2] Univ Ferrara, COPD, Dept Clin & Expt Med, I-44121 Ferrara, Italy
[3] Univ Montpellier, Dept Resp Med, F-34059 Montpellier, France
[4] Univ Modena & Reggio Emilia, Dept Resp Med, Modena, Italy
[5] Hosp Grosshansdorf, Ctr Pneumol & Thorac Surg, Grosshansdorf, Germany
[6] Leiden Univ, Med Ctr, Dept Pulmonol, Leiden, Netherlands
[7] Univ Hosp Heraklion, Dept Thorac Med, Iraklion, Greece
[8] McGill Univ, Meakins Christie Labs, Montreal, PQ, Canada
[9] Duke Univ, Med Ctr, Dept Med, Durham, NC 27710 USA