Utility and direct costs: ankylosing spondylitis compared with rheumatoid arthritis
S M M Verstappen, J W G Jacobs, D M van der Heijde, Sj van der Linden, C M Verhoef, J W J Bijlsma, A Boonen
Annals of the Rheumatic Diseases Jun 2007, 66 (6) 727-731; DOI: 10.1136/ard.2006.061283