Assessment of fatigue using the identity-consequence fatigue scale in patients with lung cancer

Objective: to evaluate the properties of the ICFS (Identity-Consequence Fatigue Scale) in patients with lung cancer (LC) and to assess intensity of fatigue and associated factors in these patients. Methods: A cross-sectional study with LC patients in Brazil. ICFS data were obtained from chronic heart disease (CHD) and healthy individuals(HI) for comparison with LC patients. Portuguese language version of ICFS was administered to 50 LC patients by two independents interviewers. To test for reproducibility, questionnaire was re-administered to the same patients. The patients were submitted to spirometry, six-minute walk test, Epworth sleepiness scale (ESS), hospital anxiety and depression scale (HADS), quality of life (QF) SF-36. The inflammatory status was avaliated by C-reative protein (CRP) and fatigue by ICFS and fatigue severity scale (FSS). To validate the ICFS we assessed the correlations of its scores with these variables. Results: the sample comprised 50 patients in each group (LC, CHD and HI). For the LC group, the intrarater reliability of ICFS summary variables fatigue experiences and fatigue impacts using the intraclass correlation coefficient (ICC) ranged from 0.94 to 0.76 and ICC for inter-rater reliability ranged from 0.94 to 0.79 respectively. The ICFS presented an excellente internal consistency and Bland-Altman plots showed good test-retest concordance. The ICFS correlated significantly with FSS, HADS, SF-36, ESS and CRP. Mean ICFS scores from LC patients were significantly different from CHD and HI group scores. Conclusion: ICFS is a valid and reliable instrument for evaluating LC patients. Depression, QF and CRP levels were significantly associated with fatigue.