Conflict of interest: None.
Funding: This research was supported by grants from the Canadian
Institute for Health Research (MOP-67765 and MOP-69081) and the
Arthritis Society of Canada (99/093; renumbered to 99/0143 in 2001).
C.M.B was supported by a Peterborough K.M. Hunter Graduate Studentship,
a Canadian Arthritis Network Graduate Student Award and a Toronto
Star Bursary Award.