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.