title: Assessment of symptom exacerbations in a longitudinal study of children with Tourette's syndrome or obsessive-compulsive disorder.
abstract: OBJECTIVE
  The severity of tic and obsessive-compulsive (OC) symptoms varies over time. Consequently, how do we, as clinicians, know when a change in symptom severity occurs that falls outside of the normal range of fluctuation? The goal of this study was to describe the level of symptom severity fluctuation over time and to establish an objective, prospective, and quantitative method for identifying symptom exacerbations in children with Tourette's syndrome, obsessive-compulsive disorder (OCD), or both. A second major aim was to assess whether fluctuations in tic and OC symptom severity covaried with one another.
  
  
  METHODS
  Monthly consecutive Yale Global Tic Severity Scale and Children's Yale-Brown Obsessive Compulsive Scale scores were prospectively obtained in 64 children diagnosed with Tourette's syndrome and/or OCD for periods ranging from 3 to 39 months. Exacerbation thresholds were estimated by using state-of-the-art bootstrap methods. These thresholds were then independently evaluated by asking two expert clinicians to identify, retrospectively, clinically significant exacerbations based on a review of all available clinical and research records.
  
  
  RESULTS
  The severity of tic and OC symptoms displayed a high degree of intrasubject variability. Exacerbation thresholds, which incorporated the change score from the previous month and the current symptom score, provided the best agreement with those of expert clinicians. When both tic and OC symptoms were present, they showed a significant degree of covariation.
  
  
  CONCLUSIONS
  Evidence-based treatments are coming of age. The use of valid, clinician-rated severity scales will likely become a standard part of clinical practice. Bootstrapping methods may provide a quantitative and convenient way to obtain clinically valid thresholds to assess tic and OC symptom exacerbations. This method has the potential to be applied to other symptom domains where exacerbation thresholds are needed.
authors.affiliation: Yale University School of Medicine, New Haven, CT 06520-7900, USA.
authors.forename: Haiqun
authors.initials: H
authors.lastname: Lin
authors.forename: Chin-Bin
authors.initials: CB
authors.lastname: Yeh
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
authors.forename: Lawrence
authors.initials: L
authors.lastname: Scahill
authors.forename: Heidi
authors.initials: H
authors.lastname: Grantz
authors.forename: Diane B
authors.initials: DB
authors.lastname: Findley
authors.forename: Liliya
authors.initials: L
authors.lastname: Katsovich
authors.forename: Jessica
authors.initials: J
authors.lastname: Otka
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Lombroso
authors.forename: Robert A
authors.initials: RA
authors.lastname: King
authors.forename: James F
authors.initials: JF
authors.lastname: Leckman
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000465:Algorithms; D002648:Child; D003237:Connecticut; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000523:psychology; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D012680:Sensitivity and Specificity; D005879:Tourette Syndrome / Q000175:diagnosis* / Q000523:psychology