title: Do anti-smooth muscle antibodies predict development of autoimmune hepatitis in patients with normal liver function? - A retrospective cohort review.
abstract: BACKGROUND
  The presence of anti-smooth muscle autoantibody (SMA) in Autoimmune Hepatitis (AIH) is well established. However, there are no data demonstrating the clinical significance in patients with normal liver function and few showing positive predictive value for AIH when alanine aminotransferase (ALT) is raised.
  
  
  METHODS
  We retrospectively established outcomes in a cohort of 251 consecutive patients with positive tubular or glomerular SMA. Patient records were checked for 12years after the positive SMA result to identify development of AIH.
  
  
  RESULTS
  Of 202 patients with SMA and ALT <55IU/L, one (0.5%) had a subsequent diagnosis of AIH and this patient probably had abnormal ALT at the time of SMA detection. 22% of 45 patients with raised ALT (>55IU/L) and 23% of 43 patients with persistently raised ALT (>3months duration), had a diagnosis of AIH on follow up. Of 10 patients with AIH, 80% were diagnosed within three months of the positive SMA.
  
  
  CONCLUSIONS
  Progression to AIH in patients with normal liver function and positive SMA-T/G is rare but patients with positive SMA and raised ALT (>55IU/L) should be referred to secondary care for investigation. Positive predictive value of SMA with raised ALT for AIH was 22%.
authors.affiliation: Hull York Medical School, University of Hull, Cottingham Road, Hull, HU6 7RX, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Healey
authors.affiliation: Department of Gastroenterology and Hepatology, Hull Royal Infirmary, Anlaby Road, Hull, HU3 2JZ, UK.
authors.forename: Lynsey
authors.initials: L
authors.lastname: Corless
authors.affiliation: Immunology Department, Castle Hill Hospital, Cottingham, HU16 5JQ, UK.
authors.forename: Pavels
authors.initials: P
authors.lastname: Gordins
authors.affiliation: Immunology Department, Hull Royal Infirmary, Hull, UK. Electronic address: steve.holding@hey.nhs.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: Holding
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D005260:Female; D019693:Hepatitis, Autoimmune / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D008099:Liver / Q000276:immunology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000276:immunology*; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies; D015415:Biomarkers
keywords: Autoimmune hepatitis; autoantibodies; indirect immunofluorescence; screening; smooth muscle antibodies