Trauma Linked to Arthritis in Psoriasis Patients

Dr. Gladman's study provides additional support for the association between trauma and incident PsA.

In this study, individuals with PsA were matched to psoriasis patients, and investigators found that injury requiring medical attention, heavy lifting, and severe infection were associated with the development of PsA.

Of course, many important questions remain to be addressed.

Could the retrospective designs of these case-control studies be strongly influenced by recall bias? This is possible but unlikely to account for these findings, given that both RA and psoriasis subjects have been used as controls.

A second question centers on the mechanisms that underlie this interesting association.

Two potential explanations have been suggested: the activation of proinflammatory molecules (such as nerve growth factor) that are produced in the psoriatic plaques, or high-level biomechanical stress to the synovial-entheseal complex, which triggers an innate immune response and subsequent inflammation.

Evidence amassed from several different sources supports the concept that trauma may be associated with the onset of PsA.

An adequately powered prospective study of psoriasis patients, with strict case definitions and appropriate control groups, will be required to adequately test the hypothesis and to understand the magnitude of a particular risk factor. Genetic risk factors could also be analyzed in such a study.

In the meantime, we await the details of Dr. Gladman's analysis, and we should make an effort to catalogue the events that are temporally related to the onset of inflammatory arthritis in our patients.

CHRISTOPHER T. RITCHLIN, M.D., is professor of medicine at the University of Rochester (N.Y.). He reports having no relevant conflicts of interest.