[1] Ghent Univ Hosp, Dept Resp Med, Ghent, Belgium
[2] Erasmus MC, Univ Med Ctr Rotterdam, Dept Epidemiol, POB 2040, NL-3000 CA Rotterdam, Netherlands
[3] Univ Ghent, Fac Pharmaceut Sci, Dept Bioanal, Ghent, Belgium
[4] Erasmus MC, Univ Med Ctr Rotterdam, Dept Med Informat, Rotterdam, Netherlands
[5] Erasmus MC, Univ Med Ctr Rotterdam, Dept Internal Med, Rotterdam, Netherlands
[6] Erasmus MC, Univ Med Ctr Rotterdam, Dept Resp Med, Rotterdam, Netherlands