Validation of a brief, reliable scale to measure knowledge about the health risks associated with obesity

Background: Obesity represents a serious threat to health through its association with conditions such as type 2 diabetes mellitus, coronary heart disease and certain types of cancer. Knowledge regarding risk to health is an important determinant of behaviour and is the focus of many health education strategies. To the authors' knowledge, there is no valid and reliable measure of knowledge regarding the health risks associated with obesity. Aim: To validate a short, reliable psychometric scale measuring knowledge regarding the effects of obesity on health, the Obesity Risk Knowledge (ORK-10) scale. Methods: The ORK-10 scale was administered to a sample of individuals with no specific obesity-related expertise (n = 230) and a sample of experts (n = 200). Univariate and multivariate statistical analyses were used to investigate the scale's criterion validity. Results: The ORK-10 scale has good internal consistency (Cronbach's alpha coefficient > 0.7) and is acceptable for use in a UK adult population with an estimated reading age of 12-13 years. The scale demonstrated strong criterion validity, as those with educational or vocational expertise in the field of obesity achieved significantly higher scores than nonexperts ( median 9.0 vs 4.0, Z = -17.364; P < 0.001). This relationship was maintained after controlling for the potentially confounding factors of age and level of education. Nonexperts demonstrated low levels of knowledge regarding the health risks associated with obesity. Conclusions: The ORK-10 scale meets standard psychometric criteria for reliability and validity. This scale could be used to assess the effectiveness of health education interventions, to target the provision of health information and to investigate the interaction between knowledge and obesity-related behaviour.