Assessment of a short diabetes knowledge instrument for older and minority adults

Abstract

Purpose: The purpose of the study was to assess the performance of a Short Diabetes Knowledge Instrument (SDKI) in a large multi-ethnic sample of older adults with diabetes and to identify possible modifications to improve its ability to document diabetes knowledge.

Research design and methods: A sample of 593 African American, American Indian, and white female and male adults 60 years and older, with diabetes diagnosed at least 2 years prior, was recruited from 8 North Carolina counties. All completed an interview that included a 16-item questionnaire to assess diabetes knowledge. A subsample of 46 completed the questionnaire a second time at a subsequent interview. Item-response analysis was used to refine the instrument to well-performing items. The instrument consisting of the remaining items was subjected to analyses to assess validity and test-retest reliability.

Results: Three items were removed after item-response analysis. Scores for the resulting instrument were lower among minority and older participants, as well as those with lower educational attainment and income. Scores for test-retest were highly correlated.

Conclusions: The SDKI (13-item questionnaire) appears to be a valid and reliable instrument to evaluate knowledge about diabetes. Assessment in a multi-ethnic sample of older adults suggests that this instrument can be used to measure diabetes knowledge in diverse populations. Further evaluation is needed to determine whether or not this instrument can detect changes in knowledge resulting from diabetes education or other interventions.

Figure

The item characteristic curves (ICC) (solid line) and information curves (dash line) for diabetes knowledge items retained in the Short Diabetes Knowledge Instrument (SDKI). The ICC shows the probability of a respondent correctly answering the item as a function of the knowledge level (scale on left) of the respondent. The information curve shows the level of accuracy of the knowledge score (scale on right).