title: Precision and sources of variability in the assessment of rheumatoid arthritis erosions by HRpQCT.
abstract: To assess the precision and the sources of variation due to repositioning of the manual measurement of erosions located on the metacarpophalangeal joints (MCP) with High-Resolution peripheral Quantitative Computed Tomography (HRpQCT) in rheumatoid arthritis (RA).
  
  
  
  RA patients with at least one erosion on the 2nd, 3rd or 4th MCP on conventional radiographs were included. Two scans were performed the same day with repositioning. The main outcome was to calculate the short-term precision of the width, depth, and volume of erosions. Secondary outcomes were intra-operator and inter-operator precision, the least significant change, and the sources of variability of the measurement.
  
  
  
  Twenty-nine patients were included, allowing analysis of 406 erosions from 0.9 to 3mm of diameter. Intraclass correlation coefficients (ICC) for the precision of the measurement of the axial width, axial depth, and volume after repositioning were 0.80, 0.96, and 0.99, respectively. RMS CV and RMS SD were 16%, 0.26mm; 17.5%, 0.32mm; and 19.7%, 0.93mm3, respectively. For intra-operator precision, ICCs were 0.92, 0.97, and 0.99 with RMS CV of 16%, 16.4%, and 18.7%, respectively. Inter-operator precision of the volume was 0.99 with RMS CV of 14%. Least significant change of width, depth, and volume were 0.3mm, 0.2mm, and 0.3mm3. There was no significant correlation with bone microarchitecture parameters.
  
  
  
  HRpQCT analysis is a reproducible method to characterize and measure erosions, without effect of the repositioning. However, we showed weak precision in manual measurement due to intra-operator variability.
authors.affiliation: Service de rhumatologie, CHR d'Orléans, 1, rue Porte-Madeleine, 45032 Orléans, France; Université Francois-Rabelais, 37000 Tours, France. Electronic address: nadaii@hotmail.fr.
authors.forename: Nada
authors.initials: N
authors.lastname: Ibrahim-Nasser
authors.affiliation: Inserm U1059, SAINBIOSE, université de Lyon, 42023 Saint-Étienne, France; Département de rhumatologie, université de Saint-Étienne, 42055 Saint-Étienne, France.
authors.forename: Hubert
authors.initials: H
authors.lastname: Marotte
authors.affiliation: Service du DIM, CHR d'Orléans, 1, rue Porte-Madeleine, 45032 Orléans, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Valery
authors.affiliation: Service de rhumatologie, CHR d'Orléans, 1, rue Porte-Madeleine, 45032 Orléans, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Salliot
authors.affiliation: I3MTO, EA 4708, université d'Orléans, 45032 Orléans, France.
authors.forename: Hechmi
authors.initials: H
authors.lastname: Toumi
authors.affiliation: Service de rhumatologie, CHR d'Orléans, 1, rue Porte-Madeleine, 45032 Orléans, France; I3MTO, EA 4708, université d'Orléans, 45032 Orléans, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Lespessailles
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008875:Middle Aged; D057285:Precision Medicine / Q000379:methods*; D011786:Quality Control; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Erosions; HRpQCT; Precision; Rheumatoid arthritis