BACKGROUND: Serum vitamin D level is commonly low in patients with inflammatory bowel disease (IBD). Although there is a growing body of evidence that links low vitamin D level to certain aspects of IBD such as disease activity and quality of life, data on its prevalence and how it varies across disease phenotype, smoking status and treatment groups are still missing. MATERIALS AND METHODS: Patients diagnosed with IBD between 2010 and 2011 were recruited. Demographic data and serum vitamin D levels were collected. Variance of vitamin D level was then assessed across different treatment groups, disease phenotype, disease activity and quality of life scores. RESULTS: A total of 238 (55.9% male) patients were included. Overall, 79% of the patients had either insufficient or deficient levels of vitamin D at diagnosis. Patients needing corticosteroid treatment at 1 year had significantly lower vitamin D levels at diagnosis (median 36.0 nmol/l) (P=0.035). Harvey-Bradshaw Index (P=0.0001) and Simple Clinical Colitis Activity Index scores (P=0.0001) were significantly lower in patients with higher vitamin D level. Serum vitamin D level correlated significantly with SIBQ score (P=0.0001) and with multiple components of SF12. Smokers at diagnosis had the lowest vitamin D levels (vitamin D: 34 nmol/l; P=0.053). CONCLUSION: This study demonstrates the high prevalence of low vitamin D levels in treatment-naive European IBD populations. Furthermore, it demonstrates the presence of low vitamin D levels in patients with IBD who smoke.

Center for Digestive Diseases Karolinska University Hospital Stockholm Sweden

Clinic of Gastroenterology University of Medicine 'Victor Babes' Timisoara Romania Balkans

Department of Gastroenterology Adelaide and Meath Hospital TCD Dublin Ireland

Department of Gastroenterology and Hepatology Soroka Medical Centre Ben Gurion University of the Negev Faculty of Health Sciences Beer Sheva Israel

Department of Gastroenterology Faculty of Medicine and Health Örebro University Örebro

Department of Gastroenterology Hospital Povisa Vigo

Department of Gastroenterology Instituto de Investigación Biomédica Galicia Sur Estrutura Organizativa de Xestión Integrada de Vigo Spain

Department of Gastroenterology Medical Academy Lithuanian University of Health Sciences Kaunas Lithuania

Department of Gastroenterology North Zealand University Hospital Roskilde Denmark

Department of Hepatology and Gastroenterology Aarhus University Hospital Aarhus

Department of Medicine Solna Karolinska Institutet

Department of Pediatrics Hvidovre Hospital University of Copenhagen Hvidovre

Department of Surgical Oncological and Gastroenterological Sciences University of Padua Padua

Division of Gastroenterology Medical School and University Hospital of Ioannina Greece

Focused Research Unit for Molecular Diagnostic and Clinical Research IRS Center Sonderjylland Hospital of Southern Jutland Aabenraa

Gastroenterology Department Hospital São João

Gastroenterology Department Odense University Hospital Odense C

Gastroenterology Department Slagelse Hospital Slagelse

Gastroenterology Division Mater Dei Hospital Malta

Herning

Hospital Budweis South Bohemia

IBD Clinical and Research Centre Iscare Prague Czech Republic

IBD Department St Mark's Hospital London UK

IBD Unit Hull and East Yorkshire NHS Trust

Institute of Pharmacology and Therapeutics Faculty of Medicine of the University of Porto Porto Portugal

Medical Department The National Hospital of the Faroe Islands Torshavn Faroe Islands

Medical Department Viborg Regional Hospital Viborg

Nicosia Private Practice Cyprus

Pekka Collin Department of Gastroenterology and Alimentary Tract Surgery Tampere University Hospital Tampere Finland

Semmelweis University Budapest Hungary

Tartu University Hospital University of Tartu Tartu Estonia

U O Gastroenterologia ed Endoscopia Digestiva Ospedale Morgagni Pierantoni Forlì Italy

University Hospital Center Zagreb School of Medicine University of Zagreb Zagreb Croatia

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