Background. The purpose of the present study was to examine
the measurement properties of
positive affect items among the Japanese population.
Methods. Responses to the Japanese version of the Center for
Epidemiologic Studies Depression
Scale and four additional negatively revised items of the original
positive affect items were
compared for 85 Japanese psychiatric out-patients with
dysphoric-mood-related symptoms and 255
demographically matched controls.
Results. Responses to positive affect items were generally
comparable between the two groups,
whereas responses to negative symptom items were markedly different
(P<0·002 for all
comparisons). The group difference was most marked for symptom
persistence. Responses to the
four negatively revised items of positive affect revealed a similar
picture to that of the negative
symptom items. The internal consistency of the scale significantly
improved when the original
positive affect items were replaced by the negatively revised items
(P<0·001 for both).
Conclusions. Positive affect items with positive wording
cannot be used to assess depressive
disorders in the Japanese population adequately, but this can be done
with the corresponding negatively revised items.