Development of the diabetes knowledge (DKN) scales: forms DKNA, DKNB, and DKNC.

The Diabetes Knowledge Assessment (DKN) scales were developed to meet a specific need for rapid and reliable knowledge assessment in diabetic patients. Item format and item selection from an initial pool of 89 items were determined by pilot-testing over 300 diabetic subjects. Reliability analysis of the resulting 40 multiple-choice items, with a further sample of 56 subjects, gave a Cronbach's alpha coefficient of 0.92. Parallel forms DKNA, DKNB, and DKNC, each of 15 items selected from the parent set, had alpha coefficients above 0.82 and correlated 0.90 with each other. A full clinical trial, using DKNA, DKNB, and DKNC in randomized order of presentation, was conducted with 219 subjects attending a 2-day diabetes education program. Overall DKN scores improved from 7.6 (51%) to 11.3 (75%). Analysis of variance confirmed that DKNA, DKNB, and DKNC were equivalent forms at pretest. Mean posttest scores on DKNB were lower than the other scales (P less than 0.001), but variances were equivalent for all three. A specific local change in the education program format was found to account for this discrepancy in the DKNB posttest mean. In situations where comprehensive assessment of diabetes knowledge would be time-consuming and unnecessary, these results indicate that rapid and reliable assessment is possible with a scale of only 15 validated items. The development of parallel forms of the scale extends the range of retesting possibilities for diagnosis and research.