ERRATUM

This article refers to:

Ankylosing spondylitis in Danish and Norwegian twins: occurrence and the relative importance of genetic vs. environmental effectors in disease causation

Scand J Rheumatol 2008;37:120-6 In the article by Pedersen OB et al published in the March/April issue of the Scandinavian Journal of Rheumatology (Scand J Rheumatol 2008;37:120–6) the use of per cent and per mil symbols were incorrect and should be corrected as follows: Results section, subsection Occurrence of AS (p. 123): The prevalence of definite AS was 0.9‰ (95% CI: 0.4‰, 1.8‰) in Norwegian and 1.0‰ (95% CI: 0.7‰, 1.3‰) in Danish twins [instead of, The prevalence of definite AS was 0.9% (95% CI 0.4–1.8) in the Norwegian twins and 1.0% (95% CI 0.7–1.3) in the Danish twins] and Discussion section (page 124): The AS prevalence was 1‰ and the AS incidence was 3/100 000 pyr among Danish twins [instead of, The AS prevalence was 1% and the AS incidence was 3/100 000 pyr among Danish twins].