A validation study of the spoken knowledge in low literacy in diabetes scale (SKILLD).

ABSTRACT

BACKGROUND: In 2005 the Spoken Knowledge in Low Literacy in Diabetes scale (SKILLD) was introduced as a diabetes knowledge test. The SKILLD has not been validated since its introduction. OBJECTIVE: To perform a validation analysis on the SKILLD. DESIGN AND PARTICIPANTS: Cross-sectional observational study of 240 patients with diabetes at an academic family practice center. MAIN MEASURES: SKILLD's correlation with an oral form of the Diabetes Knowledge Test (DKT) was used to assess criterion validity. A regression model tested construct validity, hypothesizing that SKILLD score was independently related to health literacy and education level. Content validity was tested using Cronbach's Alpha for inter-item relatedness and by comparing SKILLD items with the content of a National Institutes of Health (NIH) diabetes education website. We assessed inter-rater reliability and bias using Spearman correlation coefficients and sign-rank tests between interviewers scoring the same interview. KEY RESULTS: The SKILLD demonstrated fair correlation with the DKT (Pearson's coefficient 0.54, 95% CI=0.49 to 0.66, p<0.001). Health literacy, education level, male gender, household income, and years with diabetes were independent predictors of SKILLD score in the regression model. Cronbach's Alpha for inter-item relatedness was 0.54. There were some topics on the NIH website not addressed by the SKILLD. The inter-rater correlation coefficient was 0.79 (95% CI 0.56 to 0.91, p<0.001). CONCLUSIONS: The SKILLD is an adequate diabetes knowledge test and is appropriate for people of all literacy levels. However, it should be expanded to more completely evaluate diabetes knowledge.