Investigating the structure of ORTO-15: a meta-analytical simulation study

Missbach et al. (Appetite 108:521-524, https://doi.org/10.1016/j.appet.2016.07.010 , 2016) argued that there is a critical need to develop new tools assessing orthorexia nervosa (ON), as the existing measure (i.e., ORTO-15; Donini, Eat Weight Disord 10:28-32, https://doi.org/10.1007/BF03327537 , 2005) is an unvalidated measure, which fails to adequately assess the prevalence rate of ON. We believe that ignoring past data from ORTO-15 and going in the "baby with the bath water" direction will not catalyse but inhibit ON research. Using data from the review of the psychometric studies analysing the structure of ORTO-15 provided in Missbach et al. (2016), we selected six items, which were present in each study, and estimated effect sizes for the factor loadings. The effect sizes were used in a Monte Carlo simulation study with N = 100, 500, and 1000 to test whether the analysed model is valid. The obtained results confirmed that the six-item version of ORTO-15 is a valid and reliable measure of ON. Although new measures of ON are needed, the past data also provide valuable insight into a better understanding of ON.