Productivity costs among patients with rheumatoid arthritis: the influence of methods and sources to value loss of productivity
S M M Verstappen, A Boonen, H Verkleij, J W J Bijlsma, E Buskens, J W G Jacobs
Annals of the Rheumatic Diseases Dec 2005, 64 (12) 1754-1760; DOI: 10.1136/ard.2004.033977