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No association between urbanisation, neighbourhood deprivation and IBD: a population-based study of 4 million individuals
  1. Agnieszka Butwicka1,2,
  2. Amir Sariaslan1,
  3. Henrik Larsson1,
  4. Jonas Halfvarson3,
  5. Pär E Myrelid4,
  6. Ola Olén5,6,
  7. Louise Frisen7,8,
  8. Paul Lichtenstein1,
  9. Jonas F Ludvigsson1,9
  1. 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  2. 2 Department of Child Psychiatry, Medical University of Warsaw, Warsaw, Poland
  3. 3 Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
  4. 4 Division of Surgery, Department of Clinical and Experimental Medicine, Faulty of Health Sciences, Linköping University and Department of Surgery, County Council of Östergötland, Linköping, Sweden
  5. 5 Sachs’ Children and Youth Hospital, Stockholm South General Hospital, Stockholm, Sweden
  6. 6 Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
  7. 7 Child and Adolescent Psychiatry Research Center, Stockholm, Sweden
  8. 8 Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden
  9. 9 Department of Pediatrics, Örebro University Hospital, Örebro University, Örebro, Sweden
  1. Correspondence to Dr Jonas F Ludvigsson, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm 17177, Sweden; jonasludvigsson{at}

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We read with interest the recently published work in Gut by Imhann et al.1 Although this paper suggests that genetics plays an important role in IBD,1 environmental factors clearly contribute to its aetiology.2 When Ng et al 2 reviewed environmental risk factors for IBD in this journal they noted that urbanisation may be linked to both Crohn’s disease (CD) and ulcerative colitis (UC).

We used Cox regression to estimate the effect of urbanisation and deprivation during childhood on future IBD.

From the Swedish Total Population Register,3 the government agency Statistics Sweden selected all individuals born in Sweden between 1973 and 2013 (n=4 161 280). Among these there …

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  • Contributors AB, JFL and AS wrote the first draft of the paper. AB and AS performed the statistics.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval Stockholm Ethics Review Board, Sweden.

  • Provenance and peer review Not commissioned; internally peer reviewed.

  • Data sharing statement Data can be obtained from the National Board of Health and Welfare in Sweden.

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