Objective: To test the reliability and validity of self-made BIRS (body image rating scale). Method: The scale was administrated to 185 subjects including 70 patients with body dysmorphic disorder (BDD) and 115 normal control. The internal consistency, test-retest reliability and validity were assessed in 100 subjects. Results: Correlation coefficients between factors were 0.7 or above. Cohranbach ( 0.965. Validity coefficient was 0.684 with that of each item was over 0.6. The test-retest reliability reached 0.72 and Spearman-Brown semi-structure reliability came to 0.999. Conclusion: Good internal consistency, reliability and validity were obtained. There was no difference between boy and girl in total score as well as factor scores.

Objective To investigate the accuracy of body mass index (BMI) as the evaluation standard for obesity in Miao adults in Guangxi, to find out the BMI cutoff value suitable for the evaluation standard of adult obesity, and to provide an accurate and reliable reference value for the prevention and treatment of obesity in Miao nationality adults. Methods Using a cross-sectional design, residents aged 18 years or older in the Miao villages in Rongshui Miao Autonomous County, Guangxi, were selected as the research subjects, and their body composition was measured. The percent body fat (PBF) standard was used as the ^“gold standard^” for obesity, and the BMI standard for obesity in Chinese adults was used as the positive screening standard. The accuracy of the BMI standard was evaluated, and the ROC curve analysis was used to determine the optimal BMI cutoff value for obesity in Miao adults. Results The detection rate of obesity of Miao adults in Guangxi by BMI method was lower than that by PBF method (10.3% vs 19.0%, χ²=426.62, P<0.001). The results of reliability evaluation showed that BMI was in good agreement with PBF in judging obesity (Kappa=0.59, P<0.001). BMI as a screening criterion for obesity in Miao adults showed high specificity and low sensitivity, low Yordon index, high positive predictive value and high positive likelihood ratio, and low negative predictive value and high negative likelihood ratio. When the PBF was used as the ^“gold standard^”, BMI had a good diagnostic performance for obesity in Miao adults (AUC=0.959, P<0.001). The optimal BMI cutoff points for obesity in adults of Miao nationality in Guangxi were 25.85 kg/m² and 25.55 kg/m² for men and women, respectively. Conclusion BMI is of great value for the diagnosis of obesity in Miao adults, but it should not be used as an exclusion criterion for obesity. Especially in the case of a small sample size, the risk of misclassification bias is relatively high.