title: Interobserver agreement of Medical Research Council sum-score and handgrip strength in the intensive care unit.
abstract: BACKGROUND
  Muscle weakness often complicates critical illness and is associated with devastating short- and long-term consequences. For interventional studies, reliable measurements of muscle force in the intensive care unit (ICU) are needed.
  
  
  METHODS
  To examine interobserver agreement, two observers independently measured Medical Research Council (MRC) sum-score (n = 75) and handgrip strength (n = 46) in a cross-sectional ICU sample.
  
  
  RESULTS
  The intraclass correlation coefficient (ICC) for MRC sum-score was 0.95 (0.92-0.97). The kappa coefficient for identifying "significant weakness" (MRC sum-score <48, MRC subtotal upper limbs <24) and "severe weakness" (MRC sum-score <36) was 0.68 ± 0.09, 0.88 ± 0.07, and 0.93 ± 0.07, respectively. The ICC for left and right handgrip strength was 0.97 (0.94-0.98) and 0.93 (0.86-0.97), respectively.
  
  
  CONCLUSIONS
  Interobserver agreement on MRC sum-score and handgrip strength in the ICU was very good. Agreement on "severe weakness" (MRC sum-score <36) was excellent and supports its use in interventional studies. Agreement on "significant weakness" (MRC sum-score <48) was good, but even better using the equivalent cut-off in the upper limbs. It remains to be determined whether this may serve as a substitute.
authors.affiliation: Medical Intensive Care Unit, Department of General Internal Medicine, University Hospitals Leuven, Katholieke Universiteit Leuven, Herestraat 49, B3000 Leuven, Belgium. greet.hermans@uz.kuleuven.be
authors.forename: Greet
authors.initials: G
authors.lastname: Hermans
authors.forename: Beatrickx
authors.initials: B
authors.lastname: Clerckx
authors.forename: Tine
authors.initials: T
authors.lastname: Vanhullebusch
authors.forename: Johan
authors.initials: J
authors.lastname: Segers
authors.forename: Goele
authors.initials: G
authors.lastname: Vanpee
authors.forename: Christophe
authors.initials: C
authors.lastname: Robbeets
authors.forename: Michael Paul
authors.initials: MP
authors.lastname: Casaer
authors.forename: Pieter
authors.initials: P
authors.lastname: Wouters
authors.forename: Rik
authors.initials: R
authors.lastname: Gosselink
authors.forename: Greet
authors.initials: G
authors.lastname: Van Den Berghe
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D018737:Hand Strength; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis*; D015203:Reproducibility of Results; D012720:Severity of Illness Index