FRI0659 Investigation of self-reported painful joint count as outcome measure in hand osteoarthritis
Authors: F. Kroon, J. van der Plas, S. van Beest, W. Damman, M. Kloppenburg
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background:</h3> Hand osteoarthritis (OA) research is in need of disease-specific validated instruments to measure patient-reported outcomes. Self-reported painful joint count (PJC) could be useful to assess pain, including information about the distribution of painful joints, while being less time-consuming than assessor-reported tender joint count (TJC). <h3>Objectives:</h3> To investigate the metric properties of self-reported PJC compared to assessor-reported TJC to measure pain. <h3>Methods:</h3> Symptomatic hand OA patients from the Hand OSTeoArthritis in Secondary care (HOSTAS) study marked which joints were painful on standardized hand diagrams. Pain upon palpation was scored on similar diagrams by trained nurses, who were unaware of patients' scores. Self- and assessor-reported joint counts were calculated as the sum of painful/tender joints of both hands (range 0–30). Patients also rated pain on visual analogue scale and completed Australian/Canadian Hand Osteoarthritis index pain subscale, Short Form-36 Mental/Physical Component Summary scales, and Hospital Anxiety and Depression Scale. Radiographs were scored according to Kellgren-Lawrence. MRIs of the right distal and proximal interphalangeal joints (DIPs/PIPs) were evaluated for bone marrow lesions and synovitis. Validity was investigated by assessing correlations between self-reported PJC and assessor-reported TJC, and of both joint counts with other outcome measures. Absolute agreement on joint level, and patient level intra-class correlation coefficients (ICCs) were calculated. <h3>Results:</h3> Of 524 hand OA patients (86% women, mean age 61, 90% fulfilling ACR criteria), 506 (96.9%) reported ≥1 painful joint (median PJC 8 [interquartile range (IQR) 4–13]), while nurses reported ≥1 tender joint in 426 (81.3%) patients (TJC 3 [1–7]). Patients and assessors both most frequently reported pain/tenderness in DIP 2–3, PIP 2–3 and the thumb base, and least often in metacarpophalangeal joints (MCPs) 2–5. Correlation between the joint counts was 0.38. Correlations of both joint counts with other measures were comparable, ranging from 0.11 to 0.37 (table 1). Absolute agreement was highest in MCPs 2–5 and lowest for thumb base, DIP 2–3 and PIP 2–3 (range 61%&gt;89%). ICC between joint counts was 0.28 (95% confidence interval 0.08–0.14). <h3>Conclusions:</h3> Hand OA patients reported more painful joints than assessors reported tender joints. Self-reported PJC correlated weakly with assessor-reported TJC, and other instruments measuring pain and physical health. Divergent correlations with mental health and imaging scores were even lower. Agreement between patients and assessors was highest in joints with low prevalence of pain/tenderness, but overall agreement was low. Despite apparent advantages, these results suggest that self-reported PJC and assessor-reported TJC cannot be used interchangeably, and further study of PJC as an outcome measure in hand OA is warranted. <h3>Disclosure of Interest:</h3> None declared