title: Validity and reproducibility of the Jamar dynamometer in children aged 4-11 years.
abstract: OBJECTIVE
  Validity and reproducibility of the Jamar dynamometer were evaluated in children aged 4-11 years.
  
  
  METHODS
  Hand grip strength was measured on the dominant side and non-dominant side in 67 patients who had been referred to our specialist centre in the past 3 years because of suspected myopathy. All the patients had had muscle biopsy. Sixteen out of the 67 patients proved to have myopathy, while 51 had no myopathy. The investigator was blinded against the true diagnosis and clinical course of the patients at the time of testing. Validity was assessed by the power to discriminate between patients with and without myopathy, using logistic regression analysis and receiver operating characteristic (ROC) analysis. The area under the ROC curve (AUC) was calculated as a measure of the discriminative power. Sensitivity (Se) and specificity (Sp) were assessed at a specifically chosen cut-off point. Reproducibility was assessed by evaluating the test-retest reliability in a stratified random sample of 40 patients who returned for remeasurements, using the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  AUCs ranged from 0.78 - 0.82. At an Se = 81% cut-off point, Sp varied from 67-73%. ICCs ranged from 0.91-0.93.
  
  
  CONCLUSIONS
  The Jamar dynamometer had discriminative power in children with suspected myopathy. Reproducibility was high. The Jamar dynamometer was a good, but not completely accurate, test for myopathy.
authors.affiliation: Department of Rehabilitation Medicine (HP 898), University Medical Centre Nijmegen St Radboud, PO Box 9101, 6500 HB Nijmegen, The Netherlands. w.vandenbeld@reval.umcn.nl
authors.forename: Willeke A
authors.initials: WA
authors.lastname: van den Beld
authors.forename: Gitty A C
authors.initials: GA
authors.lastname: van der Sanden
authors.forename: Rob C A
authors.initials: RC
authors.lastname: Sengers
authors.forename: André L M
authors.initials: AL
authors.lastname: Verbeek
authors.forename: Fons J M
authors.initials: FJ
authors.lastname: Gabreëls
mesh_terms: D019540:Area Under Curve; D002648:Child; D002675:Child, Preschool; D005260:Female; D018737:Hand Strength; D006801:Humans; D016015:Logistic Models; D008297:Male; D008422:Materials Testing; D053581:Muscle Strength Dynamometer; D009135:Muscular Diseases / Q000175:diagnosis*; D012372:ROC Curve; D015203:Reproducibility of Results