Diagnostic performance of anthropometric measurements in detecting elevated serum alanine aminotransferase: a school-based screening of 7271 Shenzhen adolescents

Abstract

Background Screening for elevated serum alanine aminotransferase (ALT) can help identifying individuals at the risks of chronic and metabolic diseases, but blood collection is invasive and cannot be widely used for investigations. Considered as simple and inexpensive screening indices, anthropometric measurements can be measured in a large crowd and may be important surrogate markers for ALT levels. Among adolescents, few studies focused on the diagnostic performance of anthropometric parameters such as body mass index (BMI) and BMI z-score as predictive factors for discerning an elevated ALT activity. We sought to fill this knowledge gap among Shenzhen adolescents.Methods A school-based study was performed from 9 high schools in Shenzhen during February 2017 and June 2018. Receiver operating characteristic curve was used to examine the diagnostic performance of each measurement.Results Altogether 7271 adolescents aged 9−17 years were involved. The proportion of elevated ALT greatly increased with increasing classification of BMI-z. By the sex-specific cut-offs for elevated ALT (30 U/L boys; 19 U/L girls), BMI showed the highest area under the curve of 0.789 (95% CI 0.765-0.812) and followed by weight (0.779 [0.755-0.802]), BMI-z (0.747 [0.722-0.772]), height (0.622 [0.597-0.647]), and age (0.608 [0.584-0.632]), while height-z was not capable. With the cut-off of 67.8 kg for weight and 22.6 kg/m2 for BMI, the accuracy was 87.1% for weight and 82.9% for BMI.Conclusions The presence of elevated ALT was more common in overweight or obese adolescents. BMI and weight had the superiority of detecting elevated ALT, followed by BMI-z, height, and age.