[1] Soder Sjukhuset, Karolinska Inst, Dept Clin Sci & Educ, Stockholm, Sweden
[2] Karolinska Inst, Dept Med Solna, Clin Epidemiol Unit, Stockholm, Sweden
[3] Harvard Med Sch, Massachusetts Gen Hosp, Gastroenterol Unit, Boston, MA USA
[4] Linkoping Univ, Dept Clin & Expt Med, Div Surg, Faulty Hlth Sci, Linkoping, Sweden
[5] Cty Council Ostergotland Linkoping, Dept Surg, Linkoping, Sweden
[6] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden
[7] Univ Orebro, Orebro Univ Hosp, Dept Pediat, Orebro, Sweden
[8] Univ Orebro, Fac Med & Hlth, Dept Gastroenterol, Orebro, Sweden
[9] Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden
[10] Karolinska Univ Hosp, Div Coloproctol, Ctr Digest Dis, Stockholm, Sweden
[11] Sachs Children & Youth Hosp, Dept Pediat Gastroenterol & Nutr, Stockholm, Sweden