Corrigendum to "Study protocol for the follow-up examination of the Nor-Hand study: A hospital-based observational cohort study exploring pain and biomarkers in people with hand osteoarthritis" [Osteoarthr. Cartil. Open 3 (2021) 100198].

[This corrects the article DOI: 10.1016/j.ocarto.2021.100198.].

Associations between fluorescence optical imaging and magnetic resonance imaging and symptoms in hand osteoarthritis.

OBJECTIVES: To investigate whether Fluorescence Optical Imaging (FOI) enhancement and MRI-defined synovitis are associated with pain and physical function in hand OA patients. METHODS: Bilateral FOI scans and MRI of the dominant hand were available for 221 patients. Finger joints were examined for tenderness on palpation. Pain in individual finger joints during the last 24 h and last 6 weeks and hand pain intensity by the Australian/Canadian hand index and Numeric Rating Scale were self-reported. On joint level, we applied logistic regression with generalized estimating equations to examine whether FOI enhancement and MRI-defined synovitis were associated with pain in the same joint. On subject level, we applied linear regression to assess whether FOI and MRI sum scores were associated with pain intensity and physical function. RESULTS: Metacarpophalangeal and thumb base joints were excluded from analyses due to little/no FOI enhancement. Finger joints with FOI enhancement on the composite image had higher odds (95% CI) of pain during the last 6 weeks [grade 1: 1.4 (1.2-1.6); grade 2-3: 2.1 (1.7-2.6)]. Similar results were found for joint pain during the last 24 h and joint tenderness in fingers. Numerically stronger associations were found between MRI-defined synovitis and finger joint pain/tenderness. FOI and MRI sum scores demonstrated no/weak associations with hand pain and physical function. CONCLUSION: FOI enhancement and MRI-defined synovitis were associated with pain in the same finger joint. None of the imaging modalities demonstrated consistent associations with pain, stiffness and physical function on subject level.

Study protocol for the follow-up examination of the Nor-Hand study: A hospital-based observational cohort study exploring pain and biomarkers in people with hand osteoarthritis.

Objective: This study aims to increase the understanding of pain mechanisms in hand OA and explore potential risk factors for pain development or worsening in a biopsychosocial framework. Another important aim is to validate potential soluble and imaging OA biomarkers. Design: The follow-up examination of the Nor-Hand hospital-based observational cohort study started in October 2019 and was completed in May 2021. In total, 212 of the 300 participants with hand OA who were examined at baseline attended the follow-up study. The participants underwent clinical joint examinations, medical and functional assessments, quantitative sensory testing, fluorescence optical imaging, ultrasound of the hands, acromioclavicular joints, feet, knees and hips, conventional radiographs of the hands and feet and magnetic resonance imaging of the dominant hand. Blood and urine samples were collected, and all participants answered questions about demographic factors and OA-related questionnaires. Associations between disease variables and symptoms will be examined in cross-sectional and longitudinal analyses. Longitudinal analyses will be performed to assess the predictive value of baseline variables on hand OA outcomes. Conclusion: Current knowledge about predictors for disease progression in hand OA is limited, but with longitudinal data we will be able to explore the predictive value of baseline variables on hand OA outcomes, such as changes in patient-reported outcomes or changes in soluble and imaging biomarkers. This provides a unique opportunity to gain more knowledge about the natural disease course of hand OA.

Validity and diagnostic performance of fluorescence optical imaging measuring synovitis in hand osteoarthritis: baseline results from the Nor-Hand cohort.

OBJECTIVE: Fluorescence optical imaging (FOI) demonstrates enhanced microcirculation in finger joints as a sign of inflammation. We wanted to assess the validity and diagnostic performance of FOI measuring synovitis in persons with hand OA, comparing it with magnetic resonance imaging (MRI)- and ultrasound-detected synovitis. METHODS: Two hundred and twenty-one participants with hand OA underwent FOI and ultrasound (gray-scale synovitis and power Doppler activity) of the bilateral hands and contrast-enhanced MRI examination of the dominant hand. Fifteen joints in each hand were scored on semi-quantitative scales (grade 0-3) for all modalities. Four FOI images were evaluated: one composite image (Prima Vista Mode (PVM)) and three images representing phases of fluorescent dye distribution. Spearman's correlation coefficients were calculated between sum scores of FOI, MRI, and ultrasound. Sensitivity, specificity, and area under the curve (AUC) were calculated for FOI using MRI or ultrasound as reference. RESULTS: FOI did not demonstrate enhancement in the thumb base, and the joint was excluded from further analyses. FOI sum scores showed poor to fair correlations with MRI (rho 0.01-0.24) and GS synovitis sum scores (rho 0.12-0.25). None of the FOI images demonstrated both good sensitivity and specificity, and the AUC ranged from 0.50-0.61 and 0.51-0.63 with MRI and GS synovitis as reference, respectively. FOI demonstrated similar diagnostic performance with PD activity and GS synovitis as reference. CONCLUSION: FOI enhancement correlated poorly with synovitis assessed by more established imaging modalities, questioning the value of FOI for the evaluation of synovitis in hand OA.