title: Validation of a single item to assess daytime sleepiness for the Swiss Transplant Cohort Study.
abstract: BACKGROUND
  Daytime sleepiness in kidney transplant recipients has emerged as a potential predictor of impaired adherence to the immunosuppressive medication regimen. Thus there is a need to assess daytime sleepiness in clinical practice and transplant registries.
  
  
  OBJECTIVE
  To evaluate the validity of a single-item measure of daytime sleepiness integrated in the Swiss Transplant Cohort Study (STCS), using the American Educational Research Association framework.
  
  
  METHODS
  Using a cross-sectional design, we enrolled a convenience sample of 926 home-dwelling kidney transplant recipients (median age, 59.69 years; 25%-75% quartile [Q25-Q75], 50.27-59.69), 63% men; median time since transplant 9.42 years (Q25-Q75, 4.93-15.85). Daytime sleepiness was assessed by using a single item from the STCS and the 8 items of the validated Epworth Sleepiness Scale. Receiver operating characteristic curve analysis was used to determine the cutoff for the STCS daytime sleepiness item against the Epworth Sleepiness Scale score.
  
  
  RESULTS
  Based on the receiver operating characteristic curve analysis, a score greater than 4 on the STCS daytime sleepiness item is recommended to detect daytime sleepiness. Content validity was high as all expert reviews were unanimous. Concurrent validity was moderate (Spearman ϱ, 0.531; P< .001) and convergent validity with depression and poor sleep quality although low, was significant (ϱ, 0.235; P<.001 and ϱ, 0.318, P=.002, respectively). For the group difference validity: kidney transplant recipients with moderate, severe, and extremely severe depressive symptom scores had 3.4, 4.3, and 5.9 times higher odds of having daytime sleepiness, respectively, as compared with recipients without depressive symptoms.
  
  
  CONCLUSIONS
  The accumulated evidence provided evidence for the validity of the STCS daytime sleepiness item as a simple screening scale for daytime sleepiness.
authors.affiliation: University of Basel, Switzerland University Hospital Basel, Switzerland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Burkhalter
authors.forename: Anna
authors.initials: A
authors.lastname: Wirz-Justice
authors.forename: Christian
authors.initials: C
authors.lastname: Cajochen
authors.forename: Terri
authors.initials: T
authors.lastname: Weaver
authors.forename: Jürg
authors.initials: J
authors.lastname: Steiger
authors.forename: Thomas
authors.initials: T
authors.lastname: Fehr
authors.forename: Reto Martin
authors.initials: RM
authors.lastname: Venzin
authors.forename: Sabina
authors.initials: S
authors.lastname: De Geest
mesh_terms: D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D016030:Kidney Transplantation; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D013557:Switzerland
chemical_list: D007166:Immunosuppressive Agents