| Abstract: | 研究目的：本研究目的為了解六分鐘行走測試作(6MWT)為心臟術後恢復的評估工具的心理計量特性。並分析六分鐘行走距離對於心臟手術患者臨床預後的意義與影響六分鐘行走距離的相關臨床因子。
研究方法及資料：為前瞻性世代研究。於心臟手術前後對每一位受試者進行資料的測量與收集。資料包括術前資料、手術相關資料與術後資料。所有受試者在術前、出院與術後第3個月分別進行6MWT測試。術前與術後第3個月分別完成了SF-36。並於術後兩年，調查個人的死亡與再住院。為了檢驗6MWT的決定因子，在多元線性迴歸模型中我們分析研究中的可能因子。
研究結果：於術前與術後的3個月6MWT與SF-36 PF之間後具有中度和高度的相關性(分別為r=0.44和.54)與其他較無相關特質的則呈現無相關到弱相關(r=0.02到0.35 )。顯示以SF-36 PF為效標來檢驗6MWT具有身體活動功能的收斂效度與發散效度。不同NYHA組(NYHAⅠ-Ⅱvs. Ⅱ-Ⅲ)在術前和術後3個月兩個時間點，其不同組間的6MWT有顯著的差異 (F(1, 101) = 31.981, P < 0.001和F(1, 101) = 7.506, P = 0.007, 分別)。於反應性方面，從術前到出院與從術前到術後3個月等兩段區間，效果量分別為−0.37與0.73; 出院時到術後3個月效果量為1.05。Cox迴歸分析顯示經過其他的共變數調整後(年齡，左心室射出率，肌酸酐，ICU天數和住院時間)，出院時6 MWT大於300公尺(Hazard Ratio =0.116, 95% CI 0.15–0.88, P = 0.037)與左心室射出率(LVEF)>50% (Hazard Ratio =0.89, 95% CI 0.85–0.93, p < 0.001)與再住院和死亡有相關。本研究發現接受心臟手術患者的肌酸酐，年齡，性別和心律不整是術前6MWT的決定因子。而出院時的6MWT的決定因子則包括肌酸酐，年齡和性別。
結論與建議：本篇研究提供了開心者之6MWT的建構效度(收斂與發散效度)和族群效度的證據。並由效果量發現6MWT是具有反應該術後變化的特質。心臟手術後，測量出院時的6 MWT，將可篩選出心臟手術後兩年內有較高再次住院和死亡風險的患者。此外，術前或出院時的6MWT決定因子則包括有肌酸酐，年齡，性別和心律不整。6MWT具有方便執行的優點，是一項容易管理的評估工具。在術後早期評估結果，並據此比較與原本所預期的距離之間的差異。醫療人員可篩選出較高預後風險的病患，而即早進行預防性的措施。
Objective: The purpose of this study was to explore the psychometric properties of six-minute walking test (6MWT) as an evaluation tool for postoperative recovery in cardiac surgery. It investigated whether the 6MWT associated with the clinical outcome. The related clinical factors affecting the six-minute walking distance also were analyzed. Methods and Materials: The study was a prospective cohort study。Measurement and collection of data for each subject during perioperative period. The collected data included the preoperative data, surgical data and postoperative data. Participants completed the 6MWT and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) at baseline, discharge, and 3 months postoperatively, in order to analyze the construct validity and responsiveness of the 6MWT. The individual death and re-hospitalization were investigated two years after surgery for predicting the distance of 6MWT above 300 meters to the prognosis. In order to test the determining factor of 6MWT, we analyzed the possible factors in the multivariate linear regression model. Results: The results showed that the 6-minute walk distances at baseline and at 3-month follow-up were moderately to highly correlated with the physical functioning subscale of the SF-36 (rs=.44 and .54, respectively) and had weak correlations with the nonphysical functioning subscales. The recovery level of physical functioning was meaningfully associated with the 6MWT change from baseline to discharge and from baseline to 3-month follow-up. Patients with higher New York Heart Association (NYHA) Functional Classification levels had lower 6MWT. Additionally, the 6MWT was sensitive to change during the perioperative period (effect sizes from 0.51 to 1.72). Cox regression analysis was indicated that the associated 6MWT ≧ 300m at discharge and Left ventricule ejection fraction (LVEF) were proportional to hospitalization and mortality. This study also found that creatinine, age, gender and arrhythmia were the determining factors of preoperative 6MWT, and the determinants of 6MWT at discharge including creatinine, age and gender. Conclusion and Suggestion: The results of this study provide evidence for the psychometric properties of the 6MWT; therefore, clinicians and researchers can apply it to the evaluation of physical functioning in patients undergoing cardiac surgery, as the routine measuring for 6MWT at discharge after cardiac surgery would screen out patients at risk of re-hospitalization and death two years after cardiac surgery. |
