Faculty of Medicine, University of Iceland and Landspítali–The National University Hospital of Iceland, Reykjavík, Iceland (A.B.I., A.S.Á., P.T.Ö., E.S.B.).

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Faculty of Medicine, University of Iceland and Landspítali–The National University Hospital of Iceland, Reykjavík, Iceland (A.B.I., A.S.Á., P.T.Ö., E.S.B.).

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Faculty of Medicine, University of Iceland, Reykjavík, Iceland (E.R., D.A.P.).

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Faculty of Medicine, University of Iceland, Reykjavík, Iceland (E.R., D.A.P.).

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Landspítali–The National University Hospital of Iceland, Reykjavík, Iceland (B.R.G.).

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Faculty of Medicine, University of Iceland and Landspítali–The National University Hospital of Iceland, Reykjavík, Iceland (A.B.I., A.S.Á., P.T.Ö., E.S.B.).

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Faculty of Medicine, University of Iceland and Landspítali–The National University Hospital of Iceland, Reykjavík, Iceland (A.B.I., A.S.Á., P.T.Ö., E.S.B.).

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Landspítali–The National University Hospital of Iceland and the 4 regional hospitals in Iceland.

Icelandic Centre for Research and Landspítali–The National University Hospital of Iceland.

Note: This study was approved by the National Bioethics Committee of Iceland (VSN-16-057-V3).

Grant Support: This study was funded by the Icelandic Centre for Research (207113-051) and by the Landspítali University Hospital Research Fund (A-2018-012).

Data set: Available by license through the National Bioethics Committee of Iceland (e-mail, [email protected]is).

Björnsson, MD, PhD, Department of Gastroenterology and Hepatology, Landspítali University Hospital, Reykjavík, Iceland; e-mail, [email protected]is.

Pálsson: Sæmundargata 2, 102 Reykjavík, Iceland.