OMERACT Endorses 66/68 Joint Count Measure in Psoriatic Arthritis

OMERACT endorsed the 66/68 swollen and tender joint count SJC66/TJC68 for inclusion in the Core Outcome Measurement Set for patients with psoriatic arthritis.

Delegates at the Outcome Measures in Rheumatology (OMERACT) 2018 meeting have endorsed the 66/68 swollen and tender joint count (SJC66/TJC68) as a part of the psoriatic arthritis (PsA) Core Outcome Measurement Set. Details were published in the Journal of Rheumatology.

OMERACT members used the Filter 2.1 Instrument Selection Process to assess the SJC66/TJC68 for domain match, feasibility, numeral sense, and discrimination. They designed protocols to assess the measurement capabilities of SJC66/TJC68, and summarized the results via a Summary of Measurement Properties table that they published.

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Initially, OMERACT members addressed domain match and feasibility during a breakout group discussion at the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis 2017 meeting. During that same meeting, physicians, 2 patients, and a patient advocate addressed content validity and feasibility in small group meetings. Group consensus indicated that SJC66/TJC68 was adequate and feasible for assessing musculoskeletal disease activity/peripheral arthritis.

To assess the patient perspective on feasibility and domain match, OMERACT members conducted a web-based survey among patient research partners. They asked survey respondents whether or not they agreed that SJC66/TJC68 accurately and feasibly measured peripheral arthritis disease activity.

These patient research partners emphasized that the effective performance of the SJC66/TJC68 requires communication between the physician and patient.

OMERACT members assessed numerical sense through a systematic literature review and analysis of data from randomized controlled trials. The researchers stated that they “suggest that SJC66 and TJC68 have construct validity.”

Ultimately, the OMERACT working group concluded that SJC66/TJC88 “meets the OMERACT criteria for domain match, feasibility, truth, and discrimination.”

Among patient research partners, 100% voted “green” to endorse the SJC66/TJC68. Among all other stakeholders, 88% voted “green” to endorse.

“Through the years, the lack of standardization of the instruments to measure peripheral arthritis in PsA has resulted in the use of different instruments in [randomized controlled trials] and [longitudinal observational studies],” the researchers concluded. “After a careful assessment… the evidence supporting the measurement properties of the SJC66/TJC68 was assessed and resulted in full endorsement (green) by OMERACT as an instrument to measure [musculoskeletal] disease activity/peripheral arthritis in PsA.”

SJC66/TJC68 is the first green instrument to enter the PsA Core Outcome Measurement Set, according to the researchers.


Duarte-García A, Leung YY, Coates LC, et al. Endorsement of the 66/68 joint count for the measurement of musculoskeletal disease activity: OMERACT 2018 psoriatic arthritis workshop report [published online February 15, 2019]. J Rheumatol. doi:10.3899/jrheum.181089