title: Validity and reliability of a new tool to evaluate handwriting difficulties in Parkinson's disease.
abstract: BACKGROUND
  Handwriting in Parkinson's disease (PD) features specific abnormalities which are difficult to assess in clinical practice since no specific tool for evaluation of spontaneous movement is currently available.
  
  
  OBJECTIVE
  This study aims to validate the 'Systematic Screening of Handwriting Difficulties' (SOS-test) in patients with PD.
  
  
  METHODS
  Handwriting performance of 87 patients and 26 healthy age-matched controls was examined using the SOS-test. Sixty-seven patients were tested a second time within a period of one month. Participants were asked to copy as much as possible of a text within 5 minutes with the instruction to write as neatly and quickly as in daily life. Writing speed (letters in 5 minutes), size (mm) and quality of handwriting were compared. Correlation analysis was performed between SOS outcomes and other fine motor skill measurements and disease characteristics. Intrarater, interrater and test-retest reliability were assessed using the intraclass correlation coefficient (ICC) and Spearman correlation coefficient.
  
  
  RESULTS
  Patients with PD had a smaller (p = 0.043) and slower (p<0.001) handwriting and showed worse writing quality (p = 0.031) compared to controls. The outcomes of the SOS-test significantly correlated with fine motor skill performance and disease duration and severity. Furthermore, the test showed excellent intrarater, interrater and test-retest reliability (ICC > 0.769 for both groups).
  
  
  CONCLUSIONS
  The SOS-test is a short and effective tool to detect handwriting problems in PD with excellent reliability. It can therefore be recommended as a clinical instrument for standardized screening of handwriting deficits in PD.
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Evelien
authors.initials: E
authors.lastname: Nackaerts
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Heremans
authors.affiliation: Department of Health and Rehabilitation Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Bouwien C M
authors.initials: BC
authors.lastname: Smits-Engelsman
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Sanne
authors.initials: S
authors.lastname: Broeder
authors.affiliation: Department of Neurosciences, KU Leuven, Leuven, Belgium.|Department of Neurology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vandenberghe
authors.affiliation: Department of Neurology, A.Z. Sint-Jan Brugge-Oostende, Bruges, Belgium.
authors.forename: Bruno
authors.initials: B
authors.lastname: Bergmans
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Alice
authors.initials: A
authors.lastname: Nieuwboer
mesh_terms: D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006236:Handwriting; D006801:Humans; D008297:Male; D010300:Parkinson Disease / Q000503:physiopathology*