title: The reliability and validity of the Seasonal Pattern Assessment Questionnaire: a comparison between patient groups.
abstract: BACKGROUND
  The Seasonal Pattern Assessment Questionnaire (SPAQ) is a frequently used screening instrument in the research on Seasonal Affective Disorder (SAD). Nevertheless, studies on its reliability and validity are relatively scarce. In the present study the reliability and the contrast validity of the SPAQ are investigated.
  
  
  METHODS
  SAD patients, selected by means of a clinical interview, non-seasonal depressed out-patients, non-depressed out-patients, and a control group, are contrasted to estimate the discriminating power of the SPAQ. Also, the reliability and factor structure of the seasonality and the climate subscales are investigated. To study food intake the Seasonal Food Preference Questionnaire (SFPQ) was developed.
  
  
  RESULTS
  The SAD criterion of the SPAQ shows good specificity (94%), but a low sensitivity (44%). Discriminant analysis shows sufficient ability to classify subjects (81% correctly classified). The Global Seasonality Scale has a good internal consistency. It consists of two factors, a psychological factor and a food factor. The SFPQ is sensitive for carbohydrate intake by SAD patients.
  
  
  CONCLUSIONS
  Most SAD patients had received treatment and completed the SPAQ while they were not depressed, which may have influenced the sensitivity.
  
  
  CONCLUSIONS
  The SPAQ is not sensitive enough to be considered a diagnostic instrument for SAD. Nevertheless, it is accurate enough to be used as a screenings instrument. The only false positives were found in the depressive group. The accuracy of prevalence Figs. can be improved by completion of the SPAQ in the summer months, combined with the completion of a depression scale.
authors.affiliation: Department of Psychiatry, University Hospital Groningen, Groningen, The Netherlands. p.p.mersch@acggn.azg.nl
authors.forename: Peter Paul A
authors.initials: PP
authors.lastname: Mersch
authors.forename: Nanette C
authors.initials: NC
authors.lastname: Vastenburg
authors.forename: Ybe
authors.initials: Y
authors.lastname: Meesters
authors.forename: Antoinette L
authors.initials: AL
authors.lastname: Bouhuys
authors.forename: Domien G M
authors.initials: DG
authors.lastname: Beersma
authors.forename: Rutger H
authors.initials: RH
authors.lastname: van den Hoofdakker
authors.forename: Johannes A
authors.initials: JA
authors.lastname: den Boer
mesh_terms: D000328:Adult; D000368:Aged; D001835:Body Weight; D003863:Depression / Q000175:diagnosis* / Q000453:epidemiology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D016002:Discriminant Analysis; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D019964:Mood Disorders / Q000175:diagnosis / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results; D016574:Seasonal Affective Disorder / Q000175:diagnosis* / Q000453:epidemiology; D012680:Sensitivity and Specificity; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000453:epidemiology; D012919:Social Behavior; D011795:Surveys and Questionnaires