Validation of self assessment patient knowledge questionnaire for heart failure patients.

Background: Several studies showed insufficient knowledge and poor compliance to non-pharmacological management in heart failure patients. Only a limited number of validated tools are available to assess their knowledge. The aim of the study was to test our 10-item Patient knowledge questionnaire.

Methods: The Patient knowledge questionnaire was administered to 42 heart failure patients from Heart failure clinic and to 40 heart failure patients receiving usual care. Construct validity (Pearson correlation coefficient), internal consistency (Cronbach alpha), reproducibility (Wilcoxon signed rank test), and reliability (chi-square test and Student's t-test for independent samples) were assessed.

Results: Overall score of the Patient knowledge questionnaire had the strongest correlation to the question about regular weighing (r=0.69) and the weakest to the question about presence of heart disease (r=0.33). There was a strong correlation between question about fluid retention and questions assessing regular weighing, (r=0.86), weight of one litre of water (r=0.86), and salt restriction (r=0.57). The Cronbach alpha was 0.74 and could be improved by exclusion of questions about clear explanation (Chronbach alpha 0.75), importance of fruit, soup, and vegetables (Chronbach alpha 0.75), and self adjustment of diuretic (Chronbach alpha 0.81). During reproducibility testing 91% to 98% of questions were answered equally. Patients from Heart failure clinic scored significantly better than patients receiving usual care (7.9 (1.3) vs. 5.7 (2.2), p<0.001).

Conclusions: Patient knowledge questionnaire is a valid and reliable tool to measure knowledge of heart failure patients.