The reliability and validity of the Seasonal Pattern Assessment Questionnaire: a comparison between patient groups.
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.
Mersch
Peter Paul A
PP
Department of Psychiatry, University Hospital Groningen, Groningen, The Netherlands. p.p.mersch@acggn.azg.nl
Vastenburg
Nanette C
NC
Meesters
Ybe
Y
Bouhuys
Antoinette L
AL
Beersma
Domien G M
DG
van den Hoofdakker
Rutger H
RH
den Boer
Johannes A
JA
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