Examination of Patient Self-Reports of Exertion and Daily Activity Using Cardio-pulmonary Data Post Six Minute Walk Test in a Population of Chronic Liver Disease (CLD)

Abstract

Purpose: To examine correlations between patient self-reports of activity and exertion to objective measures of performance and cardio-respiratory fitness. Methods: Patients with histologically proven non-alcoholic fatty liver (NAFLD) or chronic hepatitis C (HCV) and a BMI >25 were eligible. Patients with HCV were not receiving anti-viral therapies. Patients with uncontrolled hypertension or other cardiac-related comorbidities were excluded. The selfreports examined were: Borg Ratings of Perceived Exertion (RPE), Human Activity Profile using the Maximum Activity Scale (MAS), Adjusted Activity Scale (AAS), Vitality Scale of SF-36 and Fatigue Severity Scale (FSS). Cardio pulmonary measures of fitness collected pre and post 6 Minute walk test (6MWT) were: O2 saturation (O2 sat pre, O2 sat post), heart rate (R (resting) HR, HRpost), change in heart rate (ΔHR), and percent of volume of maximum oxygen (VO2 max). Performance measures analyzed were average velocity and distance walked. Spearman rank sum correlations were performed. Results: Fifty-one patients completed the 6MWT [45.1% Female, Age 51.7 ± 8.0 years, Body Mass Index (BMI) 32.8 ± 5.9, 60% HCV, 40% NALFD]. Average cardio-respiratory data for the entire cohort was RHR = 72 ± 9.0 bpm, HRpost = 93.1 ± 16.0 bpm, O2 sat pre = 98.4 ± 1.5, O2 sat post = 97.2 ± 2.6 and average VO2 max = 36.9 ± 4.9 (ml/kg/min). Performance was highly correlated with cardio respiratory data: velocity was correlated with VO2max (r = -.354, p ≤ .05), RHR (r = -.298, p ≤ .05), ΔHR (r = .306, p ≤ .05). Walk distance had significant correlations (p ≤ .05) with VO2 max (r = .354), RHR (r = -.298) and change in HR (r = .312). Borg RPE was significantly (p ≤ .05) correlated with MAS (r = -.287). MAS was correlated with O2 sat pre (r = .414) significant at (p ≤ .01). AAS significantly (p ≤ .01) correlated with SF-36 vitality (r = .482) and FSS (r = -.409). FSS was correlated with SF-36 (r = -.697) significant at (p ≤ .01). No patient self reports were correlated significantly to performance or cardio respiratory data. Furthermore, BMI was not significantly correlated with performance measures or self reports. Conclusion: Ratings of perceived exertion, which show strong correlations to performance and cardio respiratory response post exercise in normal and some disease populations do not correlate in patients with CLD. Further study is required for understanding. This is not attributable to BMI.