Ann Epidemiol 2003 Apr;13(4):252-60
Jin YP, De Pedro-Cuesta J, Lopez-Abente G, Link H.
Neuroepidemiology Unit, Division of Neurology, Karolinska Institute,
Huddinge University Hospital, S-141 86, Huddinge, Sweden
PURPOSE:
To identify potential birth cohort effects in multiple sclerosis in Sweden and particularly in Stockholm county.
METHODS:
Data on multiple causes of death from multiple sclerosis during 1962 to 1995 in Sweden and 1968 to 1995 in Stockholm county were analyzed using age-period-cohort models and curvature.
RESULTS:
Mortality from multiple sclerosis was higher in Sweden than in Stockholm county, with stable time trends, slight period effects and marked age effects.
Cohorts born before or after a central period, from 1910 through 1930, registered lower mortality.
A periodic wave-form mortality pattern was identified, following a 5-to-6-year cycle for cohorts born before 1925 both in and outside Stockholm county, and changing to longer or irregular cycles for cohorts born after 1930.
CONCLUSIONS:
Although methodological constraints inducing the saw-tooth pattern cannot be excluded, these results are consistent with etiologic hypotheses claiming a role for environmental factors in multiple sclerosis.