Objective - To evaluate whether persons with a history of poliomyelitis are
at an increased risk of developing multiple sclerosis (MS). Material and m
ethods - All patients diagnosed with acute poliomyelitis in the greater cap
ital area of Copenhagen, Denmark, between 1919 and 1954 were identified and
followed with respect to MS. Information on vital status and diagnosis of
sclerosis was obtained through linkage with the Danish Civil Registration S
ystem and The Danish Multiple Sclerosis Registry, respectively. Follow-up s
tarted on the date of the establishment of the Danish Civil Registration Sy
stem (April 1, 1968) until death, emigration or December 31, 1996, whicheve
r came first. The observed incidence of MS among polio patients was compare
d with the expected incidence calculated according to national gender, age
and period specific rates of MS. Results - During 149,364 years of follow-u
p, 19 cases of multiple sclerosis were observed among 5652 polio patients c
ompared with 11.0 expected (SIR = 1.73 (1.04-2.74)). The increased risk of
MS was most pronounced in polio patients hospitalized during adolescence. N
either gender nor the acute severity of poliomyelitis modified the risk of
MS. Conclusion - Our results are based on small numbers of events, however
the findings suggest that the polio patients might be at an increased risk
of MS.