Establishing the Validity of Using the COPD Assessment Test to Screen for Fatigue in People With Chronic Obstructive Pulmonary Disease Referred to Pulmonary Rehabilitation

OBJECTIVE: Fatigue is the second most prevalent symptom in chronic obstructive pulmonary disease (COPD), yet it is often undetected in pulmonary rehabilitation. The aim of this study was to assess the validity of using a health status questionnaire (COPD Assessment Test [CAT] and CAT-energy score) to detect fatigue in people with COPD referred to a pulmonary rehabilitation program. METHODS: This study was a retrospective audit of people with COPD referred to pulmonary rehabilitation. The validity of the CAT-total score and CAT-energy score for detecting fatigue was analyzed compared to a validated fatigue questionnaire, the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F). Cut-off values defining fatigue included a CAT-total score ≥ 10, a CAT-energy score ≥ 2, and a FACIT-F score ≤ 43. Data were analyzed using 2 × 2 tables from which accuracy, sensitivity, specificity, and likelihood ratios were calculated. RESULTS: Data from 97 participants with COPD (age in years mean [SD] = 72 [9]; FEV(1)% predicted mean [SD] = 46% [18]) were used. The FACIT-F score ≤ 43 classified 84 participants (87%) as fatigued. A CAT-total score ≥ 10 yielded an accuracy of 0.87, sensitivity of 0.95, specificity of 0.31, and positive and negative likelihood ratios of 1.38 and 0.15, respectively. A CAT-energy score ≥ 2 yielded an accuracy of 0.85, sensitivity of 0.93, a specificity of 0.31, and positive and negative likelihood ratios of 1.34 and 0.23, respectively. CONCLUSION: The CAT-total score is an accurate and sensitive measure for fatigue, and the CAT could be an appropriate tool to screen for fatigue in people with COPD referred to pulmonary rehabilitation. IMPACT: Use of the CAT as a screening tool for fatigue has the potential to improve clinician awareness of fatigue, simplify the pulmonary rehabilitation assessment process by reducing survey burden, and inform fatigue management, which may subsequently reduce the symptomatic burden of fatigue in people with COPD.