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Open Access Research article

Mental comorbidity and multiple sclerosis: validating administrative data to support population-based surveillance

Ruth Ann Marrie1122*, John D Fisk3, Bo Nancy Yu2, Stella Leung2, Lawrence Elliott2, Patricia Caetano2, Sharon Warren4, Charity Evans5, Christina Wolfson67, Lawrence W Svenson1089, Helen Tremlett11, James F Blanchard2, Scott B Patten8 and for the CIHR Team in the Epidemiology and Impact of Comorbidity on Multiple Sclerosis

Author Affiliations

1 Department of Internal Medicine, University of Manitoba, Winnipeg, Canada

2 Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada

3 Health Sciences Centre, GF-543. 820 Sherbrook Street, Winnipeg, MB, Canada

4 Departments of Psychiatry and Medicine, Dalhousie University, Halifax, Canada

5 Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada

6 College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada

7 Department of Epidemiology and Biostatistics and Occupational Health, McGill University, Montreal, Canada

8 Research Institute of the McGill University Health Centre, Montreal, Canada

9 Department of Community Health Sciences, University of Calgary, Calgary, Canada

10 School of Public Health, University of Alberta, Edmonton, Canada

11 Surveillance and Assessment, Alberta Health, Edmonton, Canada

12 Department of Medicine (Neurology), University of British Columbia, Vancouver, Canada

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BMC Neurology 2013, 13:16  doi:10.1186/1471-2377-13-16

Published: 6 February 2013

Abstract

Background

While mental comorbidity is considered common in multiple sclerosis (MS), its impact is poorly defined; methods are needed to support studies of mental comorbidity. We validated and applied administrative case definitions for any mental comorbidities in MS.

Methods

Using administrative health data we identified persons with MS and a matched general population cohort. Administrative case definitions for any mental comorbidity, any mood disorder, depression, anxiety, bipolar disorder and schizophrenia were developed and validated against medical records using a a kappa statistic (k). Using these definitions we estimated the prevalence of these comorbidities in the study populations.

Results

Compared to medical records, administrative definitions showed moderate agreement for any mental comorbidity, mood disorders and depression (all k ≥ 0.49), fair agreement for anxiety (k = 0.23) and bipolar disorder (k = 0.30), and near perfect agreement for schizophrenia (k = 1.0). The age-standardized prevalence of all mental comorbidities was higher in the MS than in the general populations: depression (31.7% vs. 20.5%), anxiety (35.6% vs. 29.6%), and bipolar disorder (5.83% vs. 3.45%), except for schizophrenia (0.93% vs. 0.93%).

Conclusions

Administrative data are a valid means of surveillance of mental comorbidity in MS. The prevalence of mental comorbidities, except schizophrenia, is increased in MS compared to the general population.

Keywords:
Multiple sclerosis; Administrative data; Validation; Prevalence; Depression; Anxiety; Bipolar disorder; Schizophrenia