Development and validation testing of a weight management nutrition knowledge questionnaire for adults.

Abstract

Because no validated tool exists to assess nutrition knowledge regarding weight management we developed and tested the Weight Management Nutrition Knowledge Questionnaire (WMNKQ). The questionnaire assesses nutrition knowledge in these categories: energy density of food, portion size/serving size, alcohol and sugar sweetened beverages, how food variety affects food intake, and reliable nutrition information sources. In total 60 questions were reviewed by 6 experts for face validity and quantitative analysis was used to assess item difficulty, item discrimination, internal consistency, inter-item-correlation, test-retest reliability, construct validity, criterion validity, and convergent validity. The final WMNKQ contained 43 items. Experts removed 3 of the original 60 questions and modified 41. Eighteen items did not meet criteria for item difficulty, item discrimination, and/or inter-item correlation; 4 were retained. The WMNKQ met criteria for internal consistency (Cronbach's alpha = 0.88), reliability (test-retest correlation ρ = 0.90, P < 0.0001), construct validity (known groups comparison) - dietitians scored 16% better (p < 0.0001) than information technology workers, and criterion validity (pre- to post-intervention improvement in knowledge scores = 11.2% (95% CI 9.8-12.5, p < 0.0001)). Participants younger than age 55 scored significantly better than those over age 55 (convergent validity). The WMNKQ measures how well nutrition principles of weight management are understood.