Many of the following questions reflect items on the research agenda of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) for Outcome Measures in Rheumatology (OMERACT) 8 (May 2006) and will have task forces addressing them in the form of research projects, questionnaires, and consensus exercises.

Which joints should be included in psoriatic arthritis (PsA) assessment: carpometacarpal joints, distal interphalangeal (DIP) joints, feet DIPs? Should we perform 76, 68, 44, or 28 joint counts? Can feet DIPs be distinguished from proximal interphalangeal (PIP) joints clinically and/or radiologically? Can they be distinguished from osteoarthritis radiologically? Should we count or score?

Mease: When we set about to assess joints in the original etanercept trial, our assumption was that we needed to capture a larger number of joints than in typical rheumatoid arthritis (RA) trials, including the DIP joints of both hands and feet, as well as the carpometacarpal (CMC) joints which can be commonly affected, thus using a 76/74 joint count. Some have countered that it is difficult in many patients to assess the DIP joints of the feet, especially the smaller ones, and that assessment of the CMC joint may not be valid. Further, radiologists have grumbled that it is often difficult to distinguish the DIP joints, especially in the feet. Thus the perennial question is: Is it sufficient to count the joints, or does it add more information to score relative degree of tenderness and swelling in each joint? The Erlangen analysis of raw data from the etanercept and infliximab phase II trials suggests that counts are as distinguishing as scores, and that 76, 68, 44, and 28 joint counts are all adequate to detect differences between treatment and placebo. The only caveat is that it is worthwhile to assess at least 68 joints at study entry in order to qualify a patient, especially oligoarticular patients. FitzGerald would omit the second through fifth proximal interphalangeal (PIP) joints of the toes as difficult to assess.

Gladman: However, this may be important not only at study entry. If a patient happens to have a number of feet or distal …