[1] Erasmus Univ, Dept Ear Nose & Throat Surg, Rotterdam, Netherlands
[2] Erasmus Univ, Dept Biostat, NL-3000 DR Rotterdam, Netherlands
[3] Erasmus Univ, Dept Allergol, NL-3000 DR Rotterdam, Netherlands
[4] Univ Hosp Dijkzigt, NL-3015 GD Rotterdam, Netherlands
[5] Leyenburg Hosp, Dept Ear Nose & Throat Surg, The Hague, Netherlands