164
· DOS Abstracts
Self-reported scoliosis is not a valid method
for estimating concordance rates of Adolescent
Idiopathic Scoliosis in a Danish twin population
Mikkel Andersen, Kirsten O. Kyvik , Karsten Thomsen , Ane Simony
Sector of Spine Surgery and Research, Region of Southern Denmark, Sygehus
Lillebælt; Institute of Public Health, University of Southern Denmark; Sector of
Spine Surgery, , Aleris
Background:
The aetiology of adolescent idiopathic scoliosis is still unclear and
the true mode of inheritance has yet to be established. From the Danish twin
cohort concordance rates in monozygotic twins have previously been reported
to be 0.13¬ and in dizygotic twins 0. Studies on concordance in twin pairs pro-
vide a basis for analysing the influence of genetic versus environmental factors.
Purpose / Aim of Study:
To validate if self-reported scoliosis is a valid method
to establish incidence and concordance rates in a twin population
Materials and Methods:
All 46,418 twins registered in the Danish Twin
Registry born from 1931 to 1982 were sent a questionnaire, which included
questions about scoliosis. A sub group of 344 individuals with self- reported
scoliosis were invited to a clinical and a radiologic examination together with
their twin, in total 644 individuals/ 322 twin pairs. Zygosity was established by
genetic testing.
Findings / Results:
203 individuals (31.5% of the cohort) participated. The
total number of participants consisted of 95 twin pairs, where one or both twins
had scoliosis and 13 individuals. 35 individuals (32.4%) of the 108 participants
with self-reported scoliosis presented a clinical and radiological confirmed
curve. Of these were 5 twin pairs (4 monozygotic pairs and 1 dizygotic pair)
with scoliosis in both twins and 11 twin pairs with scoliosis in only one twin and
3 individuals where only one twin participated. Calculating concordance in twins
with curves greater than 15 degrees, we found that the pairwise concordance
rate was 0.4 (0.12-0.74) for monozygotic and 0.05 (0.01 -0.25) for dizygotic
twin pairs, probandwise concordance was 0.45 for monozygotic and 0.1 for
dizygotic pairs.
Conclusions:
Self-reported scoliosis in a Danish twin population is not a valid
method to establish the true concordance rates.
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