Healthcare and burden of disease in psoriatic arthritis. A comparison with rheumatoid arthritis and ankylosing spondylitis - Zink, A.; Thiele, K.; Huscher, D.; Listing, J.; Sieper, J.; Krause, A.; Gromnica-Ihle, E.; von Hinueber, U.; Wassenberg, S.; Genth, E.; Schneider, M.; German Collaborative Arthritis, Centres (J Rheumatol, 2006)