title: Reliability and validity of CDAI and SDAI indices in comparison to DAS-28 index in Moroccan patients with rheumatoid arthritis.
abstract: BACKGROUND
  Clinical disease activity index (CDAI) and simplified disease activity index (SDAI) are useful tools for the evaluation of disease activity in patients with rheumatoid arthritis (RA), but have not been comparatively validated in Moroccan population. Therefore, this study was designed to assess validity and reliability of CDAI and SDAI in comparison to disease activity score-28 joints (DAS-28) in Moroccan patients with RA.
  
  
  METHODS
  Patients with RA were included in a cross-sectional study. Patient characteristics and RA were collected. The disease activity was assessed by DAS-28, CDAI and SDAI. Patients were splitted into groups of remission, low, moderate and high activity on the basis of predefined cut-offs for DAS-28, CDAI, and SDAI. A Spearman correlation between composite indexes and inter-group comparison of the indexes were performed. Using DAS-28 as a gold standard, the Receiver operator characteristic (ROC) curve was used to assess the performance of a screening test at different levels.
  
  
  RESULTS
  The study was conducted with 103 patients of female predominance (87.4%). Mean age was 49.7 ± 11.4 years. Median disease duration was in the order of 8 years [3-14]. There was an excellent correlation between DAS-28 and CDAI (r = 0.95, p <0.001), CDAI and SDAI (r = 0.90, p <0.001), and DAS-28 and SDAI (r = 0.92, p <0.001). There was a good inter-rater alignment between the DAS-28 and CDAI (Weighted kappa =0.743) and there was a moderate inter-rater alignment between the DAS-28 and SDAI (Weighted kappa =0.60), and also between the SDAI and CDAI (Weighted kappa = 0.589). There was no statistically significant difference between AUROC of CDAI and SDAI as both were performed equally well.
  
  
  CONCLUSIONS
  This study is the first Moroccan case study to compare the performance of both CDAI and SDAI in evaluation of disease activity in patients with RA. Our study showed that there was a direct and excellent correlation between DAS-28 and CDAI, and SDAI and DAS-28.
  
  
  CONCLUSIONS
  Our study shows a strong positive correlation between DAS-28, CDAI and SDAI. The cut-off values for CDAI and SDAI used in western literature can be used with minor modifications in Moroccan scenario.
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. benslamaimane@gmail.com.
authors.forename: Imane Ben
authors.initials: IB
authors.lastname: Slama
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. fadouaallali@yahoo.fr.|Laboratory of Information and Research on Bone Diseases (LIRPOS-URAC 30), Mohamed V University, Souissi Rabat, Rabat, 10000, Morocco. fadouaallali@yahoo.fr.|Biostatistics Laboratory, Clinical Research and Epidemiology (LBRCE), Faculty of Medicine and Pharmacy, Mohammed V University, Souissi Rabat, Rabat, 10000, Morocco. fadouaallali@yahoo.fr.
authors.forename: Fadoua
authors.initials: F
authors.lastname: Allali
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. l.touria@hotmail.fr.
authors.forename: Touria
authors.initials: T
authors.lastname: Lakhdar
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. k_sarra99@hotmail.fr.
authors.forename: Sarra
authors.initials: S
authors.lastname: El Kabbaj
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. lamyamedrar@gmail.com.
authors.forename: Lamyae
authors.initials: L
authors.lastname: Medrare
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. ngeuleuange@yahoo.fr.
authors.forename: Ange
authors.initials: A
authors.lastname: Ngeuleu
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. hananrkain@yahoo.fr.|Laboratory of Physiology, Faculty of Medicine and Pharmacy, Mohamed V University, Souissi Rabat, Rabat, 10000, Morocco. hananrkain@yahoo.fr.
authors.forename: Hanan
authors.initials: H
authors.lastname: Rkain
authors.affiliation: Department of Rheumatology, El Ayachi Sale University-Hospital, Sale, 11000, Morocco. nhajjajhassouni@gmail.com.|Laboratory of Information and Research on Bone Diseases (LIRPOS-URAC 30), Mohamed V University, Souissi Rabat, Rabat, 10000, Morocco. nhajjajhassouni@gmail.com.|Biostatistics Laboratory, Clinical Research and Epidemiology (LBRCE), Faculty of Medicine and Pharmacy, Mohammed V University, Souissi Rabat, Rabat, 10000, Morocco. nhajjajhassouni@gmail.com.
authors.forename: Najia
authors.initials: N
authors.lastname: Hajjaj-Hassouni
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009018:Morocco / Q000453:epidemiology; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*