title: Concordance between CRP and SAA in familial Mediterranean fever during attack-free period: A study of 218 patients.
abstract: BACKGROUND
  Monitoring SAA level in attack-free FMF patients is recommended in order to adjust colchicine dose, and minimize the risk of AA amyloidosis. In countries where this test is not available, C-reactive protein (CRP), another acute phase reactant, is used instead. However, CRP is low and SAA is increased in some patients and vice versa.
  
  
  OBJECTIVE
  To determine the threshold of CRP corresponding to SAA<10mg/L in patients with FMF and to assess their concordance at the patient level.
  
  
  METHODS
  Consecutive FMF patients in attack-free period and no other cause of intermittent inflammation including infections were recruited during their regular visits in the French reference center for FMF. Demographic and genetic data were recorded; CRP and SAA were tested simultaneously. The threshold value of CRP corresponding to 10mg/L for SAA was determined and the concordance between the two markers was assessed with Cohen's kappa index.
  
  
  RESULTS
  399 samples were obtained from 218 patients, mean age of 27years (33% under 18years old), 55% of female, from Sephardic Jewish origin in 71%. MEFV mutation was M694V homozygous or compound heterozygous in 52%, and simple heterozygous in 18%. Six patients had AA amyloidosis. The appropriate CRP threshold was found to be 5mg/L in children and 8.75mg/L in adults. Global agreement with SAA<10mg/L was 84% [95% confidence interval: 82 to 86%], leading to a kappa index at 0.62 [95% confidence interval: 0.57 to 0.68].
  
  
  CONCLUSIONS
  CRP<5mg/L in FMF children or 8.75mg/L in FMF adults during attack-free periods might be a convenient substitute to guide therapeutic decisions when SAA is unavailable.
authors.affiliation: Assistance publique-hôpitaux de Paris, hôpital Tenon, Centre de référence adulte de la fièvre méditerranéenne familiale, service de médecine interne, F-75020 Paris, France; Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France. Electronic address: katia.stankovic@aphp.fr.
authors.forename: Katia
authors.initials: K
authors.lastname: Stankovic Stojanovic
authors.affiliation: Centre hospitalier de Versailles, centre de référence des maladies autoinflammatoires rares de l'enfant (CeRéMAI), service de pédiatrie, F-78150 Le Chesnay, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Hentgen
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Assistance publique-hôpitaux de Paris, hôpital Tenon, UF Bio-marqueurs inflammatoires et métaboliques, Service de biochimie, F-75020 Paris, France.
authors.forename: Soraya
authors.initials: S
authors.lastname: Fellahi
authors.affiliation: Assistance publique-hôpitaux de Paris, hôpital Tenon, Centre de référence adulte de la fièvre méditerranéenne familiale, service de médecine interne, F-75020 Paris, France; Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Sorbonne Université, UPMC université Paris 06, INSERM UMR_S933, F-75012 Paris, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Georgin-Lavialle
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Sorbonne Université, UPMC université Paris 06, INSERM UMR_S933, F-75012 Paris, France; Assistance publique-hôpitaux de Paris, hôpital Armand-Trousseau, Centre de référence adulte de la fièvre méditerranéenne familiale, Laboratoire de génétique, F-75012 Paris, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Amselem
authors.affiliation: Assistance publique-hôpitaux de Paris, hôpital Tenon, Centre de référence adulte de la fièvre méditerranéenne familiale, service de médecine interne, F-75020 Paris, France; Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Sorbonne Université, UPMC université Paris 06, INSERM UMR_S933, F-75012 Paris, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Grateau
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Assistance publique-hôpitaux de Paris, hôpital Tenon, UF Bio-marqueurs inflammatoires et métaboliques, Service de biochimie, F-75020 Paris, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Bastard
authors.affiliation: Assistance publique-hôpitaux de Paris, hôpital Tenon, Centre de référence adulte de la fièvre méditerranéenne familiale, service de médecine interne, F-75020 Paris, France; Sorbonne Universités, UPMC Université Paris 06, Département hospitalo-universitaire I2B, F-75013 Paris, France; Sorbonne Universités, UPMC Université Paris 06, INSERM, LIMICS, F-75005 Paris, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Steichen
mesh_terms: D000293:Adolescent; D000328:Adult; D002097:C-Reactive Protein / Q000378:metabolism*; D002648:Child; D018572:Disease-Free Survival; D010505:Familial Mediterranean Fever / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D055815:Young Adult
chemical_list: D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein
keywords: C reactive protein; Familial Mediterranean fever; Serum amyloid A