Division of Pulmonary and Critical Care.
Statistical Analysis of Biomedical and Educational Research Group, University of Michigan, Ann Arbor, Michigan; and.
Am J Respir Crit Care Med. 2023 Jul 15;208(2):188-195. doi: 10.1164/rccm.202208-1504OC.
Fatigue is a common and debilitating symptom for people living with interstitial lung disease (ILD). Studies on fatigue in ILD are limited, and little headway has been made toward developing interventions targeting the alleviation of fatigue. A barrier to progress is a lack of knowledge around the performance characteristics of a patient-reported outcome measure to assess fatigue in patients with ILD. To assess the validity and reliability of the Fatigue Severity Scale (FSS) for measuring fatigue in a national cohort of patients with ILD. FSS scores and several anchors were measured in 1,881 patients from the Pulmonary Fibrosis Foundation Patient Registry. Anchors included the Short Form 6D Health Utility Index (SF-6D) score and a single vitality question from the SF-6D; the University of California, San Diego, Shortness of Breath Questionnaire; FVC; Dl; and 6-minute-walk distance. Internal consistency reliability, concurrent validity, and known-groups validity were assessed. Structural validity was assessed using confirmatory factor analysis. The FSS demonstrated high internal consistency (Cronbach's α = 0.96). There were moderate to strong correlations between FSS score and patient-reported anchors (vitality question from the SF-6D [ = 0.55] and University of California, San Diego, Shortness of Breath Questionnaire total score [ = 0.70]) and weak correlations between FSS score and physiological measures (FVC [ = -0.24], percentage predicted Dl [ = -0.23], and 6-minute-walk distance [ = -0.29]). Higher mean FSS scores, indicating greater fatigue, were observed among patients using supplemental oxygen, those prescribed steroids, and those with lower percentage predicted FVC and percentage predicted Dl. The confirmatory factor analysis results suggest that the nine questions of the FSS reflect one dimension of fatigue. Fatigue is an important patient-centered outcome in ILD that is poorly correlated with physiological measures of disease severity, including lung function and walk distance. These findings further support the need for a reliable and valid measure of patient-reported fatigue in ILD. The FSS possesses acceptable performance characteristics for assessing fatigue and distinguishing different degrees of fatigue among patients with ILD.
疲劳是间质性肺疾病（ILD）患者常见且虚弱的症状。ILD 疲劳的研究有限，针对缓解疲劳的干预措施也鲜有进展。进展的障碍是缺乏对ILD 患者评估疲劳的患者报告结局测量的性能特征的了解。 评估疲劳严重程度量表（FSS）在ILD 全国队列患者中测量疲劳的有效性和可靠性。 FSS 评分和几个锚点在来自肺纤维化基金会患者注册中心的 1881 名患者中进行了测量。锚点包括简短的 6 项健康调查问卷（SF-6D）评分和 SF-6D 中的一个单一活力问题；加利福尼亚大学圣地亚哥短气问卷；FVC；DL；和 6 分钟步行距离。评估了内部一致性可靠性、同时有效性和已知组有效性。使用验证性因子分析评估结构有效性。 FSS 表现出较高的内部一致性（Cronbach's α=0.96）。FSS 评分与患者报告的锚点（SF-6D 的活力问题[=0.55]和加利福尼亚大学圣地亚哥短气问卷总分[=0.70]）之间存在中度到强相关性，而与生理测量（FVC [=−0.24]、预测 FVC 百分比[=−0.23]和 6 分钟步行距离[=−0.29]）之间的相关性较弱。使用补充氧气、服用类固醇以及预测 FVC 和预测 DL 百分比较低的患者的平均 FSS 评分较高，表明疲劳程度更高。验证性因子分析结果表明，FSS 的九个问题反映了疲劳的一个维度。 疲劳是ILD 中重要的以患者为中心的结局，与疾病严重程度的生理测量（包括肺功能和步行距离）相关性较差。这些发现进一步支持ILD 中患者报告疲劳的可靠和有效测量的必要性。FSS 在评估疲劳和区分ILD 患者不同程度的疲劳方面具有可接受的性能特征。
