title: Diagnostic outcome of muscle biopsy.
abstract: BACKGROUND
  We reviewed the diagnostic yield of muscle biopsy according to the presence or absence of muscle weakness, hyperCKemia, and electromyogaphic (EMG) abnormalities.
  
  
  METHODS
  In a retrospective study, 698 muscle biopsy reports were analyzed. Logistic regression models for myopathy and specific myopathy were fit, and receiver-operating characteristic (ROC) curves were generated to assess prediction accuracy. The probability of finding specific myopathy was considered the main indication of a positive muscle biopsy.
  
  
  RESULTS
  Isolated hyperCKemia was poorly predictive of either myopathy or specific myopathy. Combined myopathic EMG, proximal weakness, and hyperCKemia were predictive. The predictability increased proportionally to the creatine kinase (CK) level in patients with proximal weakness and myopathic EMG. Cross validation showed accuracy around 70% for a probability threshold of 50%.
  
  
  CONCLUSIONS
  The presence of hyperCKemia, proximal weakness, and myopathic EMG together were associated with highly positive diagnostic outcome of muscle biopsy. Isolated hyperCKemia had a poor diagnostic yield.
authors.affiliation: Baylor College of Medicine, Nerve and Muscle Center of Texas, 6624 Fannin Street, #1670, Houston, Texas, 77030, USA.
authors.forename: Aziz
authors.initials: A
authors.lastname: Shaibani
authors.forename: Duaa
authors.initials: D
authors.lastname: Jabari
authors.forename: Moussa
authors.initials: M
authors.lastname: Jabbour
authors.forename: Chia
authors.initials: C
authors.lastname: Arif
authors.forename: Minjae
authors.initials: M
authors.lastname: Lee
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Rahbar
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D003402:Creatine Kinase / Q000378:metabolism*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D009135:Muscular Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D003402:Creatine Kinase
keywords: EMG; creatine kinase; muscle biopsy; myopathy; weakness