[1] Karolinska Inst, Dept Mol Med & Surg, Upper Gastrointestinal Res, Stockholm, Sweden
[2] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden
[3] Karolinska Inst, Dept Environm Med, Stockholm, Sweden
[4] Ctr Espanol Invest Farmacoepidemiol, Madrid, Spain