title: Contribution of dot-blot assay to the diagnosis and management of myositis: a three-year practice at a university hospital centre.
abstract: OBJECTIVE
  Idiopathic inflammatory myopathies (IIM) are heterogeneous autoimmune diseases with wide clinical spectrum that may lead to delayed diagnosis. The aim of this study was to examine the impact of IIM-specific dot-blot assay on diagnostic process of patients presenting with muscular or systemic symptoms evocating of IIM.
  
  
  METHODS
  We collected all the prescriptions of an IIM specific dot-blot assay (8 autoantigens including Jo-1, PL-7, PL-12, SRP, Mi-2, Ku, PM/Scl and Scl-70) over a 38-month period.
  
  
  RESULTS
  316 myositis dot-blot assays (MSD) were performed in 274 patients (156 women, mean age 53±10.6 years) referring for muscular and/or systemic symptoms suggesting IIM. The timing of dot prescription through the diagnostic process was highly variable: without (35%), concomitantly (16%) or after electromyographic studies (35%). Fifty-nine patients (22%) had IIM according to Bohan and Peter's criteria. Among them, 29 (49%) had positive dot (8 Jo-1, 6 PM-Scl, 5 PL-12, 5 SRP, 2 Mi-2, 2 PL-7 and 1 Ku). Various other diagnoses were performed including 35 autoimmune disease or granulomatosis (12%), 19 inflammatory rheumatic disease (7%), 16 non inflammatory muscular disorders (6%), 10 drug-induced myalgia (4%), 11 infectious myositis (4%). Except 11 borderline SRP results and one transient PM-Scl, MSD was positive only in one case of IIM. Dot allowed clinicians to correct diagnosis in 4 cases and improved the diagnosis of IIM subtypes in 4 cases.
  
  
  CONCLUSIONS
  This study reflects the interest of myositis dot in the rapid diagnosis process of patients with non-specific muscular symptoms leading to various diagnoses including IIM.
authors: Department of Internal Medicine, and Department of Immunology, Limoges University Hospital, France.
authors: Clothilde
authors: C
authors: Martel
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Guillaume
authors: G
authors: Vignaud
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Eric
authors: E
authors: Liozon
authors: Department of Neurology, Centre de Référence "Neuropathies Périphériques Rares", Limoges University Hospital, France.
authors: Laurent
authors: L
authors: Magy
authors: Department of Neurology, Centre de Référence "Neuropathies Périphériques Rares", Limoges University Hospital, France.
authors: Gael
authors: G
authors: Gallouedec
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Kim
authors: K
authors: Ly
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Holly
authors: H
authors: Bezanahary
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Anne
authors: A
authors: Cypierre
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: François-Xavier
authors: FX
authors: Lapébie
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Sylvain
authors: S
authors: Palat
authors: Department of Internal Medicine, Limoges University Hospital, France.
authors: Guillaume
authors: G
authors: Gondran
authors: Department of Immunology, Limoges University Hospital, France.
authors: Marie-Odile
authors: MO
authors: Jauberteau
authors: Department of Internal Medicine, Limoges University Hospital, France. anne-laure.fauchais@unilim.fr.
authors: Anne-Laure
authors: AL
authors: Fauchais
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D005602:France; D006785:Hospitals, University; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood / Q000175:diagnosis* / Q000276:immunology / Q000628:therapy*; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies; D015415:Biomarkers