Prediction of Metabolically Unhealthy Phenotype By The Visceral Adiposity Index, Lipid Accumulation Product And Triglyceride-glucose Index In Chinese Women With Polycystic Ovary Syndrome

Abstract

Study question: Can visceral adiposity index (VAI), lipid accumulation product (LAP) and triglyceride-glucose (TyG) index predict metabolic unhealthiness in Chinese women with polycystic ovary syndrome (PCOS)? Summary answer: Chinese-VAI (CVAI) and LAP are the best predictors of metabolic unhealthiness encompassing metabolic syndrome (MetS), insulin resistance (IR) and dysglycaemia in Chinese women with PCOS. What is known already: Women with PCOS, both obese and non-obese, are at increased risks of metabolic derangements compared with the general population. VAI, LAP and TyG are established composite indices derived from some components of the MetS, and have been validated by previous studies as effective markers of metabolic unhealthiness as defined by the presence of MetS, IR and/or dysglycaemia. CVAI is the Chinese version of VAI calculated as -187.32+1.71*Age + 4.23*body mass index + 1.12*waist circumference + 39.76*log10[triglycerides] – 11.66*[HDL-C] (Xia et al, 2016); it has been shown to be more accurate than the original VAI in reflecting metabolic health in Chinese. Study design, size, duration: This cross-sectional observational study was based on metabolic data obtained from 459 women diagnosed with PCOS according to the Rotterdam criteria. These subjects were prospectively recruited in the Hong Kong Chinese population between 2010 and 2013. A cohort of 253 ovulatory and age-matched healthy women in the same population served as controls. Participants/materials, setting, methods: Subjects were recruited from a university hospital or community family planning clinics. Blood was taken after 8-hour fasting for metabolic assessment. MetS was defined according to the joint interim statement (Alberti et al, 2009); IR was defined by the upper quartile of the homeostasis model assessment of insulin resistance (HOMA-IR), and dysglycaemia was defined by the American Diabetes Association criteria. Prediction on metabolic unhealthiness by CVAI, VAI, LAP and TyG was analysed by ROC curve. Main results and the role of chance: The prevalence of MetS was 71 (15.5%) out of 459 PCOS subjects, compared to 3 (1.2%) out of 253 controls. We defined metabolic unhealthiness by the combined criteria as the presence of either MetS, IR and/or dysglycaemia. The prevalence of metabolic unhealthiness was 229 (49.9%) in PCOS subjects versus 68 (26.9%) in controls. For the prediction of MetS, the areas under the ROC curve (AUROC) were higher for LAP (0.945) and CVAI (0.936) compared to VAI (0.919) and TyG (0.892) (p<0.05). For prediction of IR, the AUROC were significantly higher for LAP (0.846) and CVAI (0.841) compared to VAI (0.777) and TyG (0.770) (p<0.05). For prediction of dysglycaemia, the AUROC were not significantly different among LAP (0.828), CVAI (0.821), VAI (0.812) and TyG (0.831). For prediction of metabolic unhealthiness by our combined criteria, the AUROC were significantly higher for LAP (0.860; sensitivity 70.3% and specificity 90.0% at best cutoff of 16.8) and CVAI (0.854; sensitivity 70.3% and specificity 88.7% at best cutoff of 29.2) compared to VAI (0.790; sensitivity 81.7% and specificity 62.2% at best cut-off of 0.88) and TyG (0.779; sensitivity 69.9% and specificity 74.4% at best cut-off of 8.03) (p<0.05). Limitations, reasons for caution: The cross-sectional nature of this analysis did not allow the validation of the studied metabolic indices in predicting long term cardio-metabolic morbidity, which would worth further exploration by longitudinal follow-up of the study cohort. This study was targeted at the Chinese population, and generalisability to other ethnicities needs further exploration. Wider implications of the findings: Using the MetS criteria alone will miss a number of metabolic problems like IR or dyglycaemia in women with PCOS. CVAI and LAP are simple composite metabolic indices which serve as accurate surrogate markers of the metabolically unhealthy phenotypes including MetS, IR and dysglycaemia in women with PCOS.