As far as we know, the present study was the first report on the relationship between ABSI and AAC. In the present study, we retrospectively explored the predictive importance of ABSI derived from traditional anthropometric indicators for AAC. The main findings were as follows: (1) compared with participants in lower ABSI group, those with higher ABSI showed higher levels of AAC score and higher prevalence of AAC; (2) the higher ABSI ( per 1-unit increase or regarding lower ABSI as reference) was a strong independent risk predictor of AAC in our population, although after adjusting for possible interference factors; (3) the risk of participants with higher ABSI developing into AAC seemed to be more noticeable in participants without osteoporosis and with HbA1c < 6.5%; (4) the discriminant ability of ABSI for predicting AAC was significantly higher than that of other anthropometric indicators. These results suggest that ABSI may be essential for risk management of AAC.
AAC has been widely considered as an important risk factor for CVD, and it is very common in patients with CVD. Some studies have shown that AAC is significantly associated with incident myocardial infarction[2], stroke[31], osteoporosis[32], fracture[33], CVD mortality[2], all-cause mortality[3], etc. Therefore, for these patients, the identification of pathogenic factors of AAC is of great clinical significance for primary and secondary prevention of CVD. It has been reported that advanced age, smoking, diabetes, obesity and dyslipidemia may be the risk factors of AAC[4, 9–11]. However, there may be other risk factors for AAC, such as nutrition indices.
At present, BMI and WC are the most commonly used anthropometric indicators in clinical practice, but both of them have some limitations in fat distribution. First, BMI can't not only distinguish adipose tissue from non-adipose tissue, but also can't reflect fat distribution[34]. In fact, people with excess visceral fat or central obesity are more likely to develop CVD and metabolic syndrome[14, 15]. Unlike BMI, WC has always been regarded as an alternative indicator of central obesity[35]. Previous studies have shown that WC could predict the risk of death better than BMI[36, 37], but a comparative study showed that WC was weakly or negatively correlated with subclinical CVD[19]. This suggests that the ability of WC to predict metabolic-related diseases may be overrated. The reason for this may be that the WC can't distinguish between subcutaneous fat and visceral fat, and can't reflect the difference of height and race[17]. Therefore, the WC may not be enough to fully represent central obesity. In addition, although the WHtR derived from WC and height has also been shown to predict metabolic disorders[38], it can't reflect differences of weight between individuals. Therefore, it is essential to develop a better tool to assess central obesity. It is reported that imaging technology is the gold standard for the evaluation of central obesity, but it is difficult to be widely popularized because of its high cost, complex operation and radiation. Therefore, a simple evaluation method comes into being, that is, ABSI developed by Krakauer et al. in 2012[18].
ABSI is a recently developed nutritional index composed of height, weight and WC, which is reported to be positively correlated with central obesity, metabolic related diseases and death risks[18, 22]. A subsequent study found that among teenagers, ABSI was better at identifying hypertension than BMI and WC[39]. And in Chinese adults, ABIS was a better predictor of diabetes and metabolic syndrome than BMI and WC[25]. Recent studies have also found that ABSI had a stronger correlation with all-cause mortality and CVD mortality than WC, BMI and WHtR, and it might be an important marker of atherosclerosis in patients with type 2 diabetes[40, 41]. Similarly, studies by Geraci et al. have also shown that ABSI might be considered as a better predictor of carotid atherosclerosis in patients with hypertension than traditional nutrition indexes, including WC and BMI[20]. However, some studies have found that ABSI is not superior to BMI and WC in predicting the risk of related disease or death. For example, two studies coincidentally found that in Chinese children, adolescents or adults and the elderly, the correlation between ABSI and pre-hypertension or hypertension was not higher than WC, BMI and WHtR, while the WHtR had the highest predictive power[21, 42]. In addition, another study found that although ABSI was positively correlated with arterial stiffness, its AUC value was significantly lower than that of WHtR in differentiating arterial stiffness, suggesting that ABSI might not be a better predictor of arterial stiffness in Chinese population[19]. Besides, A large European cohort study found that WC, BMI and WHtR were J-shaped correlated with all-cause mortality, while ABSI was positively correlated with all-cause mortality, and BMI was superior to ABSI in predicting CVD mortality[43]. Furthermore, a meta-analysis of 30 clinical studies showed that higher ABSI was associated with increased risk of hypertension, type 2 diabetes, CVD and all-cause death, which increased by 13%, 35%, 21% and 55%, respectively, and ABSI was superior to WC and BMI in predicting all-cause mortality, but performed poorly in predicting chronic diseases[23]. However, the studies mentioned above are aimed at exploring the relationship between ABSI and other diseases, and there is little evidence to compare ABSI with other anthropometric indicators in predicting the risk of AAC. Our research was the first to determine the ability of ABSI to recognize AAC. The results showed that there was a positive correlation between ABSI and AAC. Additionally, we found that ABSI was a better indicator of AAC than BMI, WC and WHtR, and it showed similar predictive power to baseline risk models including age, smoking history, diabetes, hypertension, osteoporosis, SBP, TG, TC, FPG, HbA1c, creatinine, uric acid, ALP, total calcium and 25-OH-VitD3 in the American population. Moreover, we also found for the first time that participants with higher ABSI had a higher risk of developing AAC in the HbA1c < 6.5% and non-osteoporosis subgroups. The reason for this might be that osteoporosis and HbA1c ≥ 6.5 were the interference factors of ABSI risk prediction model, which was also the focus of our future research. The homogenization and differentiation of the above studies may be explained by the differences in race, sample size and population characteristics.
Innovatively, our findings added to the evidence of ABSI and CVD from clinical to subclinical diseases. Moreover, we compared the predictive value of ABSI and other nutrition indexes for AAC for the first time. Therefore, this study provided additional information that the evaluation of ABSI might be of clinical significance in primary prevention to identify people at risk of CVD. In spite of this, several limitations still existed in this study. Firstly, the present study was a cross-sectional study, which could not identify the causal relationship between ABSI and AAC. Secondly, in Logistic regression analysis, we only controlled for several meaningful confounding factors, but there might be other confounding factors not included in our study, such as inflammatory indicators. Thirdly, ABSI with a very small variance was highly concentrated around the mean value, which made it difficult to define the best critical value of ABSI in clinical practice. Finally, The data of this study only came from the general population of NHANES 2013–2014, so the findings may not be applicable more populations broadly.