Readability and Comprehension of the Geriatric Depression Scale and PROMIS® Physical Function Items in Older African Americans and Latinos

Abstract

Background: Depression and physical function are particularly important health domains for the elderly. The Geriatric Depression Scale (GDS) and the Patient-Reported Outcomes Measurement Information System (PROMIS®) physical function item bank are two surveys commonly used to measure these domains. It is unclear if these two instruments adequately measure these aspects of health in minority elderly. Objective: The aim of this study was to estimate the readability of the GDS and PROMIS® physical function items and to assess their comprehensibility using a sample of African American and Latino elderly. Methods: Readability was estimated using the Flesch–Kincaid and Flesch Reading Ease (FRE) formulae for English versions, and a Spanish adaptation of the FRE formula for the Spanish versions. Comprehension of the GDS and PROMIS® items by minority elderly was evaluated with 30 cognitive interviews. Results: Readability estimates of a number of items in English and Spanish of the GDS and PROMIS® physical functioning items exceed the U.S. recommended 5th-grade threshold for vulnerable populations, or were rated as ‘fairly difficult’, ‘difficult’, or ‘very difficult’ to read. Cognitive interviews revealed that many participants felt that more than the two (yes/no) GDS response options were needed to answer the questions. Wording of several PROMIS® items was considered confusing, and interpreting responses was problematic because they were based on using physical aids. Conclusions: Problems with item wording and response options of the GDS and PROMIS® physical function items may reduce reliability and validity of measurement when used with minority elderly.