Development of the performance measure for activities of daily living-8 for patients with congestive heart failure: A preliminary study

Background: Functional limitations often lead to hospitalization, disease progression, and mortality in patients with congestive heart failure (CHF). Functional limitations become a particular problem among older patients. Self-reported questionnaires have been found to be a reliable and accurate methodology for obtaining information on functional limitations. However, current measures have been criticized for their inability to guide therapy on the basis of outcome data and for the lack of specificity of questions related to disease-specific symptoms. Objective: To develop the Performance Measure for Activities of Daily Living-8 (PMADL-8) to assess functional limitations in CHF patients and to provide preliminary data on internal consistency of the PMADL-8, as well as its reliability and validity. Methods: Using the International Classification of Functioning, Disability and Health model, functional limitation questionnaire items to assess difficulty in 8 common daily tasks in CHF patients were developed. The instrument was constructed based on input from a panel of experts and by pilot testing. Its construct and convergent validity, Rasch analysis, internal consistency, and test-retest reliability were evaluated in 50 CHF patients. Discriminative/known-group validity was investigated by comparing 37 elderly CHF patients and 37 age- and sex-matched controls from the general population. Results: Cronbach's α of the PMADL-8 was 0.94. The intraclass correlation coefficient was 0.96. The PMADL-8 was unidimensional and fitted the Rasch model. Expected differences in the PMADL-8 scores of known-groups show its discriminative/known-group validity. The PMADL-8 had good correlations with the dyspnea (r = 0.77, p < 0.01) and fatigue scores of the Marianna Heart Failure Questionnaire (r = 0.69, p < 0.01) and the New York Heart Association classification (F = 26.7, p < 0.01), demonstrating its convergent validity. Between 2 groups divided by the median scores of PMADL-8, there were significant differences in some disease-specific measures: grip strength, knee extensor muscle strength, and brain natriuretic peptide levels. Conclusion: The PMADL-8 had good internal consistency and test-retest reliability, as well as discriminative and convergent validity in CHF patients. Therefore, the PMADL-8 has the potential to be used to assess disease-specific functional limitations in CHF patients.