To the Editors:

We thank Conti et al for reporting their experience with the concept of flare and PAD, as well as for suggesting that these may be useful outcomes in evaluating patients with SLE. As suggested by Dr. Conti and colleagues, the differences noted between our study and theirs may be explained by their smaller cohort, shorter period of observation, or by ethnic differences.

Mandana Nikpour MBBS, FRACP, FRCPA*, Murray B. Urowitz MD, FRCPC*, Dominique Ibañez MSc*, Dafna D. Gladman MD, FRCPC*, * University of Toronto Lupus Clinic and Toronto Western Hospital, Toronto, Ontario, Canada.