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

Published in: The Patient - Patient-Centered Outcomes Research, 2016

Posted on RAND.org on September 20, 2016

by Sylvia H. Paz, Loretta Jones, Jose L. Calderon, Ron D. Hays

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Research Question

  1. Are the Geriatric Depression Scale (GDS) and Patient-Reported Outcomes Measurement Information System (PROMIS®) assessments, two tools used to assess physical functioning in the elderly, sufficiently understandable among their target audiences?

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.

Key Findings

  • Readability analyses estimate that some physical functioning items in the GDS and PROMIS® assessments require more than a 5th grade education to understand the answer items correctly, which exceeds the recommended level for vulnerable populations.
  • Higher-than-intended grade level readability suggests that patients with low literacy, particularly minorities and those with low incomes, may not interpret survey items as intended.
  • Caution should be exercised with comparisons of responses across sub-populations of survey participants.

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