Verification of the Validity of Depressive Symptom Scale Based on the Existing Health Questionnaire

Abstract

This paper is the first one of a series of our epidemiological studies exploring the long-term relationship between depressive symptoms and developments of lifestyle-related diseases in middle-aged and older Japanese population. Our strategy for exploring the long-term relationship is to fully utilize the annual health checkup data in a Japanese manufacturer for 14 years from 1995. The health checkup data includes answers to the questions about subjective symptoms, but does not include any of the established and generally accepted set of depression scale questions. In order to confirm that the level of depressive symptoms can be estimated by the answers to the subjective symptom questions in the existing dataset, we selected 13 questions about subjective symptoms from the questionnaire for review and asked to fill in Zung Self-rating Depression Scale questions to the people randomly sampled from the checkup population in 2008. A positive correlative relationship between the result of the selected 13 questions and SDS is confirmed by simple linear regression with a positive coefficient (p<0.001). The internal consistency is also confirmed with Cronbach's alpha 0.8871. This strongly supports our further study design examining the long-term relationship with the existing checkup data for 14 years.