[1] Univ Gothenburg, Sahlgrenska Acad, Krefting Res Ctr, Inst Me,Dept Internal Med, SE-41345 Gothenburg, Sweden
[2] Univ Gothenburg, Sahlgrenska Acad, Dept Internal Med Resp Med& Allergol, SE-41345 Gothenburg, Sweden
[3] Univ Gothenburg, Sahlgrenska Acad, Inst Med, Dept Otorhinolaryngol, SE-41345 Gothenburg, Sweden
[4] Sunderby Cent Hosp Norrbotten, Dept Med, OLIN Studies, Lulea, Sweden
[5] Umea Univ, Dept Med, Umea, Sweden