Feedback from OMERACT participants on the PsAID12.

Discussion Points by Topic
Overall Process and Evidence
  • It was noted that a significant amount of work had gone into appraising the instruments, and that both were backed by a substantial body of evidence.

  • A number of participants felt that the instrument could achieve an overall green rating given the body of evidence supporting Domain Match, Feasibility, and Construct validity, whereas other participants felt that discrimination was a critical aspect of an instrument and that an “Amber” rating in any of the discrimination subcategories should result in an overall amber rating.

Content Validity
  • It was noted that the PsAID questionnaire identifies items that may not be relevant to all patients, and concerns around how this might affect the overall score. There were also some concerns regarding the anchors used.

  • Whether patients could conceptualize “due to PsA” is referring to their condition if they do not have arthritis manifestations. Probably not a major concern, because patients voted positively for domain match. Whether patients’ ratings for items like embarrassment/fatigue/others can really differentiate that it is effect of PsA rather than other comorbidities (disease attribution).

  • Weighted scores affect feasibility.

Construct Validity
  • Potentially different constructs simultaneously assessed by items work/leisure (#4), anxiety/fear/uncertainty (#9), embarrassment/shame (#10).

  • Concern these items may not be as sensitive to change with treatment.

  • Some confusion regarding the use of a LOS to assess discrimination, with many people in the breakout group believing that this evidence must come from an RCT. Some participants felt that discrimination in clinical trials was a critical aspect for an instrument, particularly as the objective is to find instruments to be used in RCT, and this was noted to be especially important to Industry. One of 8 breakout groups suggested RCT discrimination should have been white rather than amber (15/17).

  • OMERACT TAG has clarified that cohort study longitudinal data can be taken as bronze-level evidence. Since RCT information is missing, can proceed with amber based on LOS and mandatory to address the gaps of knowledge: RCT data. Research agenda: RCT discrimination and thresholds of meaning.

  • Skin item (#3): change attribution to psoriasis instead of PsA.

  • Inconsistency across anchors for the 12 items when some would prefer consistent anchors.

  • Based on PsAID12, we cannot calculate utilities or economic analysis. There may be interpretability of some questions.

  • Overlap with other domains such as physical function and fatigue was noted.

Agreement with PsAID12 amber (or better) endorsement as core instrument for PsA RCT and LOS across breakout groups (all considered together): 71/81(88%).
  • OMERACT: Outcome Measures in Rheumatology; PsAID: Psoriatic Arthritis Impact of Disease; PsA: psoriatic arthritis; LOS: longitudinal observational study; RCT: randomized controlled trial; TAG: Technical Advisory Group.