思覺失調症執行功能表現測驗之發展

Abstract

背景與目的：執行功能損傷是思覺失調症患者常見的認知問題之一，其影響患者獨立完成日常活動的能力。常用於評量思覺失調症患者之執行功能工具包括威斯康辛卡片分類測驗 (Wisconsin Card Sorting Test, WCST)、路徑描繪測驗 (Trail Making Test)、色字測驗 (Stroop Colour-word Test)等，然而此三個評估工具有二個缺點：(一)、評量指標分數的使用不明確，且未能確認工具為評量那些執行功能能力。(二)、測驗項目非患者實際生活情境下所會從事之功能性活動，使評估結果難以推估執行功能損傷患者在實際生活中的狀況。近期研究開始使用「表現型評估工具 (performance-based assessment)」，其評量結果可直接瞭解執行功能損傷如何影響患者實際日常生活的表現，然而目前使用之表現型評估工具(執行功能表現測驗 [Executive Function Performance Test]、多重任務測驗 [Multiple Errands Test]、虛擬超市行動測驗 [Virtual Action Planning Supermarket])亦有二個缺點：(一)、評量分數代表意義不明確，未能確定應使用那個分數以代表患者之執行功能狀態。(二)、評量內容為外國之日常生活情境(文化限制)，且評量內容非針對思覺失調症患者有困難執行之功能性活動。因此本論文研究目的有三項：(一)、依據執行功能理論架構「Lezak模式」，發展適用於思覺失調症患者之表現型執行功能測驗 (Performance-based measure of Executive Functions, PEF)。(二)、驗證PEF於思覺失調症患者之施測者內信度、施測者間信度和練習效應。(三)、驗證PEF於思覺失調症患者之收斂效度及生態效度。 方法：本論文包含三個子研究。研究一為建立PEF題目，分成三階段：(一)、進行文獻回顧與訪談思覺失調症個案、照顧者、專家，以發展初版PEF。(二)、進行專家審核、認知訪談、臨床小樣本測試，以修改初版PEF。(三)、使用羅序分析 (Rasch analysis)驗證PEF修訂版之建構效度且刪除題目，以建立PEF最終版。研究二為募集二組思覺失調症方便樣本，一組方便樣本參與施測者內信度和練習效應之檢驗研究，一組方便樣本參與施測者間信度之驗證研究。每組方便樣本接受PEF間隔二週之前後測試。本研究使用組內相關係數 (intraclass correlation coefficient, ICC)驗證施測者內一致性與施測者間一致性，另計算同一施測者與不同施測者測量之最小可偵測之變化值 (minimal detectable change, MDC)。以配對t檢定檢驗是否有顯著的練習效應，且計算效應值 (Cohen’s d)以驗證練習效應大小。研究三為招募一組方便樣本接受四個評估工具施測，包括：PEF、WCST、日常生活功能評量表第三版 (Activities of Daily Living Rating Scale III, ADLRS-III)與社會功能評量表 (Personal and Social Performance scale, PSP)，以驗證PEF之收斂效度及生態效度。以Pearson’s r相關係數及Spearman’s ρ相關係數檢驗PEF之收斂效度，使用Spearman’s ρ相關係數檢驗PEF之生態效度。 結果：於研究一之第一階段，研究者彙整共47個工具性日常生活活動 (instrumental activities of daily living, IADL)項目，而設計IADL調查表。研究者使用此調查表訪談32位思覺失調症個案、27位家屬、12位精神領域臨床工作者，以編製初版PEF。在第二階段，研究者進行三次專家審核、三次認知訪談、五次臨床實際測試，而修改初版PEF。在第三階段，200位思覺失調症患者接受PEF修訂版，研究者在羅序分析中，刪除近合適度 (infit mean square)和遠合適度 (outfit mean square)超過0.6-1.4之項目。PEF最終版包括1練習題和有13個測驗題，以測量Lezak模式之四個面向：意志、計畫、目的性行動、表現效能，各個面向之題目都符合單向度建構 (unidimensionality)。於研究二，二組方便樣本各分別有60位思覺失調症患者參與研究。施測者內信度方面，PEF四個面向之ICC值為0.88-0.92，此四個面向之MDC值(意志、計畫、目的性行動、表現效能)分別為13.0、12.2、16.2、16.3；施測者間信度方面，PEF四個面向之ICC值為0.82-0.89，意志、計畫、目的性行動、表現效能面向之MDC值分別為15.8、17.4、20.9、18.6；練習效應方面，PEF二個面向(意志、計畫)之配對t檢定未達到顯著差異 (p = 0.490-0.822)，另二個面向(目的性行動、表現效能)之配對t檢定達到顯著差異 (p ≤ 0.01)。四個面向之效應值d為0.01-0.24。於研究三，共有60位思覺失調症患者符合取樣標準且參與研究，收斂效度之結果顯示，PEF四個面向間有中度到高度相關 (r = 0.68-0.92)，研究者刪除WCST中未獲得「完成第一次分類所須之卡片數」分數之患者，PEF的意志和計畫面向與WCST的「非固執產生之錯誤數」指標的相關程度偏低之外，PEF四個面向和WCST的四個認知指標(固執反應、由固執產生之錯誤數、非固執產生之錯誤數、確實完成卡片分類之次數)有中度相關 (ρ = 0.43-0.69)。生態效度方面，PEF四個面向與ADLRS-III的各個面向和總分有中度至高度相關 (ρ = 0.42-0.86)，除了ADLRS-III的休閒生活面向；PEF四個面向與PSP四個面向和總分有中度相關 (ρ = 0.31-0.56)。 結論：本論文為首次以Lezak模式，發展適用於測量思覺失調症患者之表現型執行功能評估工具。研究一結果顯示PEF有良好之建構效度(單向度建構)，每個面向題目分數可加總，以表示各個面向的特定功能。研究二結果呈現PEF應用於思覺失調症患者有良好之施測者內信度和施測者間信度，且具非常微小至小的練習效應。研究三結果顯示PEF用於思覺失調症患者具適當至良好之收斂效度及生態效度。整體而言，PEF具備有良好的信度和效度，且研究者提供PEF四個面向在同一施測者和不同施測者測量之MDC值，幫助臨床和研究人員判讀單一患者執行功能各面向的變化量，是否超過隨機測量誤差而為真實的改變。因此，臨床和研究人員可使用PEF，以掌握思覺失調症患者各個執行功能面向之狀態，據以擬定合適之治療計畫與臨床決策，進而提升治療成效。

Background and purposes: Executive dysfunction is a common cognitive deficit in patients with schizophrenia, which influences patients’ independence of carrying out daily activities. Common measures of assessing executive functions in patients with schizophrenia are the Wisconsin Card Sorting Test (WCST), Trail Making Test, Stroop Colour-word Test, etc. However, these three measures have two disadvantages: (1) score indices are unclear to represent components of executive functions; and (2) items are not functional activities, which may result in the scores not being able to reflect patients’ executive functions in real-life. Recent studies have started to use performance-based assessment that could reflect how executive dysfunction influences patients’ performance in real-life. Performance-based assessments that are currently being used in patients with schizophrenia are the Executive Function Performance Test, the Multiple Errands Test, and the Virtual Action Planning Supermarket. However, these three measures have two disadvantages: (1) the meaning of the test score is unclear, so users do not know what executive functions the scores represent; and (2) the items are based in a specific cultural context causing cultural differences and the items are not targeted at difficulties of functional activities in patients with schizophrenia. Therefore, this dissertation had three aims: (1) to develop a Performance-based measure of Executive Functions (PEF) based on an executive-function theory (Lezak model) for patients with schizophrenia; (2) to examine intra-rater reliability, inter-rater reliability, and practice effect of the PEF in patients with schizophrenia; and (3) to examine convergent validity and ecological validity of the PEF in patients with schizophrenia Methods: This dissertation contained three studies. Study 1 was to establish the PEF items, including three phases: (1) to conduct a literature review and administer interviews with patients with schizophrenia, caregivers, and experts to develop the preliminary PEF; (2) to implement expert consultation, cognitive interview, and pilot test to revise the preliminary PEF; and (3) to examine construct validity and delete items from the preliminary PEF using Rasch analysis to establish the final version of the PEF. Study 2 was to recruit two convenience samples of patients with schizophrenia. One convenience sample was for examining intra-rater reliability and practice effect. The other was for investigating inter-rater reliability. Each convenience sample was administered the PEF twice in a two-week interval. The intraclass correlation coefficient (ICC) was used to examine the extent of consistency between the two test scores administered by the same rater (intra-rater reliability) or two different raters (inter-rater reliability). The minimal detectable change (MDC) was estimated for the same rater or two different raters. Paired t-test was used for statistical analysis in practice effect. Cohen’s d was calculated to determine the size of practice effect. Study 3 was to recruit one convenience sample of patients with schizophrenia and administer four measures to examine concurrent validity and ecological validity. These four measures were the PEF, the WCST, the Activities of Daily Living Rating Scale III (ADLRS-III), and the Personal and Social Performance scale (PSP). Results: In Phase 1 of Study 1, the researcher compiled 47 instrumental activities of daily living (IADL) items to design an IADL questionnaire. The researcher used the IADL questionnaire to interview 32 patients with schizophrenia, 27 caregivers, and 12 psychiatric clinicians to develop the preliminary PEF. In Phase 2 of Study 1, the researcher conducted three expert consultations, three cognitive interviews, and five pilot tests to revise the preliminary PEF. In Phase 3 of Study 1, 200 patients with schizophrenia were administered the revised PEF. In Rasch analysis, the items with infit or outfit mean square < 0.6 or > 1.4 were deleted. The final version of the PEF contained 1 practice item and 13 test items to assess the four domains based on the Lezak model. The items of the individual domains were unidimensional. In Study 2, each of the two convenience samples had 60 patients of schizophrenia. For intra-rater reliability, ICC values of the four domains in the PEF were 0.88-0.92. The MDC values of the four domains (volition, planning, purposive action, performance effective) were 13.0, 12.2, 16.2, and 16.3, respectively. For inter-rater reliability, ICC values of the four domains were 0.82-0.89. The MDC values were 15.8, 17.4, 20.9, and 18.6 for volition, planning, purposive action, performance effective domains, respectively. Regarding practice effect, paired t-test was not statistically significant (p = 0.490-0.822) for volition and planning domains, but paired t-test was statistically significant (p ≤ 0.01) for purposive action and performance effective domains. The Cohen’s ds of the four domains were 0.01-0.24. In Study 3, 60 patients with schizophrenia participated. For convergent validity, the results showed moderate to strong correlations (r = 0.68-0.92) between the four domains. Patients who did not received a score in the index of “trials to complete first category” of the WCST were deleted. Moderate correlations (ρ = 0.43-0.69) were found among the four domains of the PEF and the four cognitive indices of the WCST (i.e., perseverative responses, perseverative errors, nonperseverative errors, and number of categories completed), except the low correlations between nonperseverative errors and two PEF domains (i.e., volition and planning). Regarding ecological validity, moderate to strong correlations (ρ = 0.42-0.86) were shown among the four domains of the PEF and the domains and total score of the ADLRS-III, except for the leisure domain. Moderate correlations (ρ = 0.31-0.56) were found among the four domains of the PEF and the domains and total score of the PSP. Conclusions: This dissertation was the first to develop the performance-based assessment to measure executive functions in patients with schizophrenia. The results of Study 1 supported construct validity (i.e., unidimensionality). That is, the items’ scores of each domain could be summed up to represent its domain-specific function. The results of Study 2 showed that the PEF had good intra-rater and inter-rater reliabilities, and trivial and small practice effects in patients with schizophrenia. The results of Study 3 showed that the PEF had sufficient convergent validity and ecological validity. As a whole, the PEF has good reliability and validity. The researcher provides the MDC values of the four domains in the PEF administered by one rater or different raters. The MDC values are useful for clinicians and researchers to determine whether the change of each domain in an individual’s score was real (beyond random measurement error). Therefore, the PEF is able to assist clinicians and researchers in understanding executive functions in patients with schizophrenia, and making treatment plans and clinical decisions to increase treatment efficacy.