To the Editor:

We are very pleased that our original observation that TNFα blockade can induce marked improvement/regression of enthesitis and osteitis in SpA has been confirmed by Olivieri and colleagues.

They describe a case in which a dramatic response, with rapid and sustained improvement, was achieved after 3 infusions of infliximab in a patient with undifferentiated SpA. Recent double-blind studies have confirmed the efficacy of the TNF blocking agents infliximab (1, 2) and etanercept (3) in the treatment of the different subtypes of SpA. Likewise, the experience reported by Olivieri et al confirms our own (4), showing the efficacy of these drugs in the treatment of enthesitis, the characteristic pathologic manifestation of these diseases.

These are, however, early days in our experience with these drugs. Importantly, Olivieri and colleagues raise the question of long-term benefit. Although >300 patients with SpA have been reported in trials worldwide, general experience is still short-lived. This is clearly an issue that will determine the cost-effectiveness of this therapy. Studies are already in place to answer this question.

Helena Marzo-Ortega MD*, Dennis McGonagle MD*, Paul Emery MD*, * University of Leeds, Leeds, UK.