The risk of multiple sclerosis in bereaved parents: A nationwide cohort study in Denmark.
BACKGROUND
Previous studies have suggested that psychological stress may play a role in the risk of multiple sclerosis (MS), but the evidence is very limited.


OBJECTIVE
To examine the association between MS and a well-defined major stressful life event: the death of a child.


METHODS
In this follow-up study based on nationwide and population-based registers, all 21,062 parents who lost a child younger than 18 years from 1980 to 1996 in Denmark were included in the exposed cohort and 293,745 matched parents who did not lose a child in the unexposed cohort. The two cohorts were followed for incident MS from 1980 to 1997. Hazard ratios (HR) with 95% CI were calculated as the measure of association between the exposure and MS, using the Cox proportional hazards regression model.


RESULTS
Two hundred fifty-eight MS patients were identified (28 in the exposed cohort and 230 in the unexposed cohort). The exposed parents had an increased risk of MS (HR 1.56, 95% CI 1.05 to 2.31), which is significant only when follow-up was at least 8 years. The HR for definite/probable MS was 1.42 (95% CI 0.90 to 2.24). Parents who lost a child unexpectedly had an HR of 2.13 (95% CI 1.13 to 4.03) for all MS, which is higher than that for other bereaved parents (HR 1.33; 95% CI 0.81 to 2.16).


CONCLUSIONS
Psychological stress may play a role in the development of MS.
Li
J
J
Danish Epidemiology Science Centre, Department of Epidemiology and Social Medicine, University of Aarhus, Denmark. jl@soci.au.dk
Johansen
C
C
Brønnum-Hansen
H
H
Stenager
E
E
Koch-Henriksen
N
N
Olsen
J
J
D000328:Adult; D001601:Bereavement; D015331:Cohort Studies; D003718:Denmark; D006801:Humans; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology / Q000209:etiology*; D016016:Proportional Hazards Models; D012307:Risk Factors; D013315:Stress, Psychological / Q000150:complications*