Comorbidity is associated with pain-related activity limitations in multiple sclerosis.
BACKGROUND
Comorbidities are common in multiple sclerosis (MS). The high prevalence of pain in MS is well-established but the influence of comorbidities on pain, specifically, pain-related interference in activity is not.


OBJECTIVE
To examine the relationship between comorbidity and pain in MS.


METHODS
We recruited 949 consecutive patients with definite MS from four Canadian centres. Participants completed the Health Utilities Index (HUI-Mark III) and a validated comorbidity questionnaire at 3 visits over 2 years. The HUI's pain scale was dichotomized into two groups: those with/without pain that disrupts normal activities. We used logistic regression to assess the association of pain with each comorbidity individually at baseline and over time.


RESULTS
The incidence of disruptive pain over two years was 31.1 per 100 persons. Fibromyalgia, rheumatoid arthritis, irritable bowel syndrome, migraine, chronic lung disease, depression, anxiety, hypertension, and hypercholesterolemia were associated with disruptive pain (p<0.006). Individual-level effects on the presence of worsening pain were seen for chronic obstructive pulmonary disease (odds ratio [OR]: 1.50 95% CI: 1.08-2.09), anxiety (OR: 1.49 95% CI: 1.07-2.08), and autoimmune thyroid disease (OR: 1.40 95% CI: 1.00-1.97).


CONCLUSIONS
Comorbidity is associated with pain in persons with MS. Closer examination of these associations may provide guidance for better management of this disabling symptom in MS.
Department of Internal Medicine, College of Medicine, Faculty of Health Sciences, University of Manitoba, 820 Sherbrook Street, Winnipeg, Canada R3A1R9.
K M
KM
Fiest
Departments of Psychiatry, Medicine, Psychology & Neuroscience, Dalhousie University, 6299 South Street, Halifax, Canada B3H4R2.
J D
JD
Fisk
Departments of Psychiatry & Community Health Sciences, Cumming School of Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Canada T2N4Z6.
S B
SB
Patten
Division of Neurology, Faculty of Medicine, University of British Columbia, 2329 West Mall, Vancouver, Canada V6T1Z4.
H
H
Tremlett
Departments of Epidemiology & Biostatistics, Occupational Health, & Medicine, McGill University, 1020 Pine Avenue West, Montreal, Canada H3A 1A2.
C
C
Wolfson
Faculty of Rehabilitation Medicine, University of Alberta, 116 Street & 85 Avenue, Edmonton, Canada T6G2R3.
S
S
Warren
Department of Experimental Medicine, University of British Columbia, 2329 West Mall, Vancouver, Canada V6T1Z4.
K A
KA
McKay
Department of Psychology, St. Francis Xavier University, Antigonish, Canada B0H1X0.
L
L
Berrigan
Department of Internal Medicine, College of Medicine, Faculty of Health Sciences, University of Manitoba, 820 Sherbrook Street, Winnipeg, Canada R3A1R9; Department of Community Health Sciences, College of Medicine, University of Manitoba, 820 Sherbrook Street, Winnipeg, Canada R3A1R9. Electronic address: rmarrie@hsc.mb.ca.
R A
RA
Marrie
D002170:Canada / Q000453:epidemiology; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009103:Multiple Sclerosis / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology*; D010146:Pain / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D010147:Pain Measurement; D015995:Prevalence; D057566:Self Report; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
Cohort; Comorbidity; Multiple sclerosis; Pain; Quality of life