Outcome measures
| Outcome measures | Definition/description |
| Primary outcome measure | |
| ACR20 | 20% improvement in American College of Rheumatology response criteria; composite measure based on tender and swollen joint counts, patient’s assessment of pain, patient and physician global assessment of disease activity, patient’s assessment of physical function and acute-phase reactant value |
| Secondary outcomes | |
| Composite measures of disease activity | |
| MDA | Minimal Disease Activity; composite measure based on tender and swollen joint counts, Psoriasis Area and Severity Index or psoriasis-affected BSA; patient pain, patient global activity, HAQ and tender entheseal points |
| PASDAS | Psoriatic Arthritis Disease Activity Score; composite measure based on patient and physician assessments of disease activity, peripheral joint counts, dactylitis, enthesitis, acute-phase reactant value and SF-36 physical component score |
| DAS28 | Disease Activity Score based on 28 joints; based on tender and swollen joint counts, patient assessment of general health and an acute-phase reactant value |
| SDAI | Simplified Disease Activity Index; based on swollen and tender joint counts, acute-phase reactant value, and patient and physician assessments of disease activity |
| CDAI | Clinical Disease Activity Index; based on swollen and tender joint counts, and patient and physician assessments of disease activity |
| Measures of non-arthritic PsA disease activity | |
| Leeds dactylitis score | Based on circumference and tenderness of affected digits |
| SPARCC | Spondyloarthritis Research Consortium of Canada; measures tenderness in 16 entheseal sites |
| NAPSI | Nail Psoriasis Severity Index; based on psoriasis in nail bed and matrix |
| BSA | Psoriasis-affected body surface area reported as a percentage |
| sPGA | Static physician global assessment; based on the severity of induration, erythema and scaling of psoriasis lesions |
| Patient-reported outcomes | |
| HAQ-DI | Health Assessment Questionnaire Disability Index; based on patient difficulties with eight quality-of-life categories |
| SF-36 | Short Form (36) Health Survey; based on eight quality-of-life domains |
| Exploratory outcome | |
| mTSS | Modified Total Sharp Score; scoring system for X-rays of the hands and feet |