title: Analysis of correlation and causes for discrepancy between quantitative and semi-quantitative Doppler scores in synovitis in rheumatoid arthritis.
abstract: The aim of this study was to evaluate the association between two semi-quantitative Doppler US scoring systems (SQS), and the quantitative scoring (QS) of Doppler pixel count.
  
  
  
  Adult patients with RA and inadequate clinical response to anti-rheumatic therapy were examined with musculoskeletal US (MSUS). Dorsal MSUS of the wrists, MCP and MTP 2-5 were performed. MSUS images with sign of synovitis were collected and the QS was measured. Five assessors blinded to the QS evaluated the images independently, according to either SQS method. Association between QS and SQS was studied using correlations and multilevel models taking into account the clustering of ratings at the rater, patient and joint levels.
  
  
  
  Analysis of the 1190 ratings revealed a strong correlation (ρ = 0.89, P < 0.0001) and significant associations (P < 0.0001) between QS and SQS. Correlations between QS and SQS according to Szkudlarek et al. (ρ = 0.87, P < 0.0001) or Hammer et al. (ρ = 0.91, P < 0.0001) were similar. A total of 239 (20.1%) images were given a SQS grade that did not match that expected based on initial QS, using pre-defined cut-offs. Main explanations for discrepancies were different perceived region of interest (40.7%) and Doppler pixel count near cut-offs between SQS grades (32.3%).
  
  
  
  We showed that both SQS methods correlated well with QS to assess synovitis, but SQS methods are intrinsically limited when the Doppler pixel count is close to the cut-offs between the SQS grades. Analysis discrepancies between these methods may help further revision of criteria used to assess disease activity with MSUS in RA.
authors.affiliation: Department of Rheumatology, institute of medicine, Karolinska University Hospital hamed.rezaei@karolinska.se.|Unit of Clinical Therapy Research, Inflammatory Diseases (ClinTRID), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Hamed
authors.initials: H
authors.lastname: Rezaei
authors.affiliation: Unit of Clinical Therapy Research, Inflammatory Diseases (ClinTRID), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Af Klint
authors.affiliation: Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway.
authors.forename: Hilde Berner
authors.initials: HB
authors.lastname: Hammer
authors.affiliation: Center for Rheumatology and Spine Disease, Copenhagen, Denmark, Rigshospitalet.
authors.forename: Lene
authors.initials: L
authors.lastname: Terslev
authors.affiliation: APHP, Hôpital Ambroise Paré, Rheumatology Department, Boulogne-Billancourt, INSERM U1173, Laboratoire d'Excellence INFLAMEX, UFR Simone Veil, Versailles-Saint-Quentin University, Saint-Quentin en Yvelines.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: D'Agostino
authors.affiliation: Department of Rheumatology, institute of medicine, Karolinska University Hospital.
authors.forename: Yogan
authors.initials: Y
authors.lastname: Kisten
authors.affiliation: Department of Rheumatology, institute of medicine, Karolinska University Hospital.
authors.forename: Laurent
authors.initials: L
authors.lastname: Arnaud
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000188:drug therapy; D005260:Female; D050823:Hand Joints / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055361:Multilevel Analysis; D012720:Severity of Illness Index; D013585:Synovitis / Q000000981:diagnostic imaging* / Q000188:drug therapy; D018608:Ultrasonography, Doppler / Q000379:methods*
chemical_list: D018501:Antirheumatic Agents
keywords: musculoskeletal ultrasound; rheumatoid arthritis; scoring systems