羅序模式檢定貝氏憂鬱量表第二版之建構效度

Application of Rasch Measurement Model in the Construct Validity of the Beck Depression Inventory-II

憂鬱症是精神疾患中常見的疾病之一，臨床上憂鬱症的診斷是根據專科醫師的判斷為主，輔以標準化量表。根據文獻搜尋結果，使用度較高的量表之一為貝氏憂鬱量表(BDI-II)。由於BDI-II的建構效度仍須加以驗證，因而本研究的目的是探討BDI-II應用在台灣憂鬱症病患之內在一致性、建構效度、項目與個案能力配合度（敏感度）。本研究樣本來自於北部某醫學中心的精神科病房，在徵得病患同意後，個案完成BDI-II問卷。共有245位個案參與，平均年齡為41.67歲，標準差為14.78。包括57位男性(23.5%), 42.4%為已婚。診斷依據DSM-IV均為憂鬱症。本研究應用羅序測量模式分析資料，以WINSTEPS3.56版本進行分析。結果發現，BDI-II的第6和7題不符合模式預期，予以刪除後再次分析發現，除了第8和第12題之外，其餘項目均符合。可構成單一建構內容。BDI-II的內在一致性達0.92。此外，BDI-II項目可將個案的憂鬱情況分為5個層次。憂鬱症狀中，最常出現的是無價值感，而較少出現的是難以專注。BDI-II的4分等級適當，並無錯置現象。項目難易度和個案能力配對結果顯示，題目難易度能涵蓋所有個案的能力範圍。本研究證實貝氏憂鬱量表具有可接受之內在一致性、建構效度及敏感度。從項目難易度順序分析，憂鬱症症狀初期之表現大多和認知心理症狀有關，而身體的症狀出現較晚。未來需進一步探討縮短版BDI-II測驗的可能性以及電腦化適性測驗之發展。

Depression is one of the most common mental illnesses. The clinical diagnosis of depression is based on psychiatrist’s judgment and sometimes, combined use of relevant standardized assessments The Beck Depression Inventory (BDI-II version) is one of the most used scales. The purpose of the study is to examine the internal consistency, construct validity and sensitivity of the BDI-II using Rasch measurement model. 245 patients with depression were recruited from a psychiatric inpatient ward in the northern part of Taiwan. The average age of the subjects is 41.67 years old (SD=14.78). There are 57 male (23.5%). Among them, 42.4% are married. All subjects were diagnosed as depression based on DSM-IV. Rasch computer software WINSTEPS 3.59 was used to analyze the data. The results showed that after deleting 2 items (6 & 7) and keep 2 borderline items (8 & 12) in the result, all items fit the Rasch model. The Cronbach α of the BDI-II is .92. The BDI-II could separate the subjects into 5 different levels of depression. The most commonly endorsed item is “worthlessness”, and the least commonly endorsed item is “concentration difficulty”. The rating scale of the BDI-II is appropriate. The item difficulty of the scale matches with the person’s level of depression to form a sensitive scale for patients with depression in a various level of depression. The study supported the construct validity, sensitivity and internal consistency of the BDI-II for depression in Taiwan. The most commonly endorsed symptoms related to psychological symptoms. Further reduction of the number of items of the BDI-II may increase the usefulness of the scale.