title: Vascular comorbidities in multiple sclerosis: a nationwide study from Denmark.
abstract: To investigate the occurrence of vascular comorbidities before and after the clinical onset of multiple sclerosis. In this combined case-control and cohort study, all Danish born citizens with onset of multiple sclerosis 1980-2005 were identified from the Danish Multiple Sclerosis Registry and randomly matched with controls regarding year of birth, gender, and municipality on January 1st in the year of multiple sclerosis (MS) onset (index date). Individual-level information on comorbidities was obtained from several independent nationwide registries and linked to the study population by unique personal identification numbers. To assess the presence of vascular comorbidities before and after MS onset, cases and controls were followed from January 1977 to the index date, and from the index date through December 2012. We used logistic regression to calculate odds ratios (ORs) and Cox regression to calculate hazard ratios (HRs). Before the index date, MS cases had a decreased probability for cerebrovascular comorbidity [OR 0.69 (95 % CI 0.48-0.99, p = 0.043)], and a numerically but not statistically significant decreased probability for cardiovascular comorbidity [OR 0.87 (95 % CI 0.71-1.07, p = 0.188)]. After the index date, MS cases had an increased risk for cerebrovascular comorbidity [HR 1.84 (95 % CI 1.69-2.00, p < 0.0005)], and for cardiovascular comorbidity [HR 1.08 (95 % CI 1.02-1.15, p = 0.013)]. The lower occurrence of cerebrovascular comorbidities in cases prior to MS onset could be due to protective immune mechanisms, while the higher occurrence of vascular comorbidities in cases after MS onset could be because of converging causal pathways of the coexisting diseases. These findings deserve to be studied closer in a broader spectrum of comorbidities in MS.
authors.affiliation: Department of Neurology, Danish Multiple Sclerosis Center, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen, Denmark. anja.thormann.01@regionh.dk.|The Danish Multiple Sclerosis Registry, Department of Neurology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark. anja.thormann.01@regionh.dk.
authors.forename: Anja
authors.identifier: http://orcid.org/0000-0002-8046-5101
authors.initials: A
authors.lastname: Thormann
authors.affiliation: Department of Neurology, Danish Multiple Sclerosis Center, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen, Denmark.|The Danish Multiple Sclerosis Registry, Department of Neurology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.
authors.forename: Melinda
authors.initials: M
authors.lastname: Magyari
authors.affiliation: The Danish Multiple Sclerosis Registry, Department of Neurology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.|Department of Clinical Epidemiology, Clinical Institute, University of Aarhus, Olof Palmes Allé 43-45, 8200, Aarhus N, Denmark.
authors.forename: Nils
authors.initials: N
authors.lastname: Koch-Henriksen
authors.affiliation: The Danish National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, 1353, Copenhagen K, Denmark.
authors.forename: Bjarne
authors.initials: B
authors.lastname: Laursen
authors.affiliation: Department of Neurology, Danish Multiple Sclerosis Center, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen, Denmark.
authors.forename: Per Soelberg
authors.initials: PS
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D016017:Odds Ratio; D012042:Registries; D012307:Risk Factors; D012737:Sex Factors; D014652:Vascular Diseases / Q000453:epidemiology*; D055815:Young Adult
keywords: Comorbidity; Epidemiology; Multiple sclerosis; Vascular comorbidity