Predictive value of functional limitation for disease severity in patients with mild chronic heart failure

Background: We aimed to verify a measure for functional limitation using the Performance Measure for Activity of Daily Living-8 (PMADL-8) clinical assessment tool. This tool was utilized to determine disease severity by comparing disease severity with physiological and demographic variables, which have been well documented as predictors for mortality and rehospitalization in chronic heart failure (CHF) patients. Methods: We consecutively enrolled 125 CHF patients with impaired left ventricular systolic function who underwent cardiopulmonary exercise testing in Nagoya University Hospital. We measured PMADL-8, which had a total score that ranged from 8 to 32 points, in which higher scores indicated severe functional limitations to evaluate the patient's functional limitations and evaluate clinical physiologic variables, which were established as prognostic factors of CHF. First, the association between PMADL-8 and other clinical variables was analyzed by correlation coefficients, and then, multivariate regression analysis was performed to select independent correlate factors. Lastly, we identified the optimal PMADL-8 threshold for detecting disease severity by comparing with the threshold for disease severity in selected variables. Results: The PMADL-8 indicated excellent correlation with peak oxygen uptake (peakVO₂) (r=-0.743, p<0.001), and the multivariate regression analysis revealed that peakVO₂ was independently correlated with the PMADL-8 (p<0.001). The optimal PMADL-8 threshold for detecting a peakVO₂ value of 18ml/min/kg was 18 points. Similarly, a peakVO₂ value of 14ml/min/kg was 22 points, and a peakVO₂ value of 16ml/min/kg was 20 points. Conclusions: Our data indicate that functional limitation as evaluated by the PMADL-8 is well correlated with peakVO₂. PMADL-8 may have potential as a clinical assessment tool to manage disease status in CHF patients.