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Published online before print October 29, 2008, doi:10.1212/01.wnl.0000333252.78173.5f)
© 2009 American Academy of Neurology Comorbidity delays diagnosis and increases disability at diagnosis in MSFrom the Department of Medicine (R.A.M.), University of Manitoba, Winnipeg, Canada; Department of Medicine (R.H.), Stanford University, CA; Department of Biostatistics (G.C.), University of Alabama at Birmingham, AL; and Division of Neurology (T.T., D.C., T.V.), Barrow Neurological Institute, Phoenix, AZ. Address correspondence and reprint requests to Dr. Ruth Ann Marrie, Health Sciences Center, GF 543, 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada rmarrie{at}hsc.mb.ca Background: Comorbidity is common in the general population and is associated with adverse health outcomes. In multiple sclerosis (MS), it is unknown whether preexisting comorbidity affects the delay between initial symptom onset and diagnosis ("diagnostic delay") or the severity of disability at MS diagnosis. Objectives: Using the North American Research Committee on Multiple Sclerosis Registry, we assessed the association between comorbidity and both the diagnostic delay and severity of disability at diagnosis. In 2006, we queried participants regarding physical and mental comorbidities, including date of diagnosis, smoking status, current height, and past and present weight. Using multivariate Cox regression, we compared the diagnostic delay between participants with and without comorbidity at diagnosis. We classified participants enrolled within 2 years of diagnosis (n = 2,375) as having mild, moderate, or severe disability using Patient Determined Disease Steps, and assessed the association of disability with comorbidity using polytomous logistic regression. Results: The study included 8,983 participants. After multivariable adjustment for demographic and clinical characteristics, the diagnostic delay increased if obesity, smoking, or physical or mental comorbidities were present. Among participants enrolled within 2 years of diagnosis, the adjusted odds of moderate as compared to mild disability at diagnosis increased in participants with vascular comorbidity (odds ratio [OR] 1.51, 95% CI 1.12–2.05) or obesity (OR 1.38, 95% CI 1.02–1.87). The odds of severe as compared with mild disability increased with musculoskeletal (OR 1.81, 95% CI 1.25–2.63) or mental (OR 1.62, 95% CI 1.23–2.14) comorbidity. Conclusions: Both diagnostic delay and disability at diagnosis are influenced by comorbidity. The mechanisms underlying these associations deserve further investigation.
Abbreviations: BMI = body mass index; EDSS = Expanded Disability Status Scale; MS = multiple sclerosis; NARCOMS = North American Research Committee on Multiple Sclerosis; NINDS = National Institute of Neurological Disorders and Stroke; NMSS = National Multiple Sclerosis Society; OR = odds ratio; PDDS = Patient Determined Disease Steps.
Received March 16, 2008. Accepted in final form July 7, 2008. Supplemental data at www.neurology.org Editorial, page 108 e-Pub ahead of print on October 29, 2008, at www.neurology.org. Supported partly by NIH, National Institute of Child Health and Human Development, Multidisciplinary Clinical Research Career Development Program Grant K12 HD04909. The NARCOMS Registry is supported by the Consortium of Multiple Sclerosis Centers. Disclosure: Author disclosures are provided at the end of the article.
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