Usefulness scale for patient information material (USE) - development and psychometric properties

BACKGROUND One economical way to inform patients about their illness and medical procedures is to provide written health information material. So far, a generic and psychometrically sound scale to evaluate cognitive, emotional, and behavioral aspects of the subjectively experienced usefulness of patient information material from the patient's perspective is lacking. The aim of our study was to develop and psychometrically test such a scale. METHODS The Usefulness Scale for Patient Information Material (USE) was developed using a multistep approach. Ultimately, three items for each subscale (cognitive, emotional, and behavioral) were selected under consideration of face validity, discrimination, difficulty, and item content. The final version of the USE was subjected to reliability analysis. Structural validity was tested using confirmatory factor analysis, and convergent and divergent validity were tested using correlation analysis. The criterion validity of the USE was tested in an experimental design. To this aim, patients were randomly allocated to one of two groups. One group received a full version of an information brochure on depression or chronic low back pain depending on the respective primary diagnosis. Patients in the second group received a reduced version with a lower design quality, smaller font size and less information. Patients were recruited in six hospitals in Germany. After reading the brochure, they were asked to fill in a questionnaire. RESULTS Analyzable data were obtained from 120 questionnaires. The confirmatory factor analysis supported the structural validity of the scale. Reliability analysis of the total scale and its subscales showed Cronbach's α values between .84 and .94. Convergent and divergent validity were supported. Criterion validity was confirmed in the experimental condition. Significant differences between the groups receiving full and reduced information were found for the total score (p<.001) and its three subscales (cognitive p<.001, emotional p=.001, and behavioral p<.001), supporting criterion validity. CONCLUSIONS We developed a generic scale to measure the subjective usefulness of written patient information material from a patient perspective. Our construct is defined in line with current theoretical models for the evaluation of written patient information material. The USE was shown to be a short, reliable and valid psychometric scale.