| BackgroundIn recent decades,the global prevalence of overweight and obesity among children has increased dramatically.Obesity in children not only causes a variety of near-term health problems but also increases the risk of cardiovascular disease and mortality in adulthood.Obesity is a chronic disease on the pathophysiologic basis of elevated body fat mass.Body mass index(BMI)is often used as an evaluation indice of obesity in practice because of its simplicity.Due to BMI is unable to distinguish between fat mass and fat free mass,it has many limitations in the assessment of obesity in children.Therefore,a more accurate body composition assessment is necessary for children.Fat mass index(FMI)and fat mass percentage(FMP)have been proven to be reliable indices for obesity evaluation.With the prevalence of obesity in the pediatric population,high carotid intimamedia thickness(cIMT)has been observed in children.Cohort studies have shown that high cIMT was an independent predictor of long-term cardiovascular diseases morbidity and mortality.Of note,high cIMT in children is mostly a reversible change,which can be delayed or even reversed to normal levels if timely intervention is applied.Therefore,it is of public significance to assess the risk factors of high cIMT and implement targeted strategies and measures in childhood,to reduce the increasingly heavy burden of cardiovascular diseases from the source.Many studies have shown that obesity was associated with high cIMT in children,but indirect indices such as BMI were mainly used to evaluate obesity status in most previous studies.However,there were few studies on the associations between direct obesity indices(e.g.,FMI and FMP)and high cIMT in children,and the conclusions were inconsistent.Epidemiological studies have shown that body fat distribution affected the risk of cardiovascular disease independently of total fat mass.As far as we know,no studies have examined the association between body fat distribution and high cIMT in children.Moreover,the screening efficacy of different obesity indices in high cIMT in children is unclear.This study aims to examine the associations between elevated body fat mass indices(FMI,FMP,subcutaneous fat mass[SFM],and visceral fat mass[VFM])and high cIMT in children,and to compare the screening efficacy of indirect(BMI,waist circumference[WC]，and waist-to-height ratio[WHtR])and direct(FMI and FMP)obesity indices in high cIMT,aiming to provide evidence for early prevention of high cIMT in children.Objectives1.To examine the associations between the increase of FMI,FMP,SFM,and VFM and high cIMT in children.2.To compare the efficacy of BMI,WC,WHtR,FMI,and FMP in screening high cIMT in children.MethodsThe participants were from the "Huantai Childhood Cardiovascular Health Cohort Study",which used a convenient cluster sampling method to select one public primary school in Huantai County,Zibo City,Shandong Province from November 2017 to January 2018.A total of 1 515 children aged 6-11 years were included in the baseline survey.This study used data from the most recent follow-up survey in 2021,a total of 1 322 children aged 10-15 years were included after excluding participants with missing data.According to the 25th,50th,and 75th percentiles of sex and age,four body fat mass indices(FMI,FMP,SFM,and VFM)were classified as lower(<P25),medium(P25～P50),higher(P50～P75),and high(≥P75)status,respectively.Firstly,covariance analysis was used to examine the associations of the status of four body fat mass indices with cIMT levels.The multivariable logistic regression model was used to examine the associations of the status of four body fat mass indices with high cIMT,and the odds ratio(OR)and 95%confidence intervals(95%CIs)were calculated.Secondly,the restrictive cubic spline(RCS)analysis was used to examine the doseresponse relationships between the elevated levels of four body fat mass indices and high cIMT.Finally,the receiver operating characteristic(ROC)curve analysis was used to compare the efficacy of BMI,WC,WHtR,FMI,and FMP in screening high cIMT.The multivariable logistic regression analysis was used to examine the associations of the standardized Z-values(normalized score calculated by sex and age)of the above five indices and obesity status defined by the above five indices with high cIMT.Results1.Associations of elevated body fat mass with high cIMT in childrenThe cIMT levels and the prevalence of high cIMT increased with the elevated status(i.e.,lower,medium,higher,and high status)of FMI(cIMT levels were 537.0μm,542.0 μm,551.0 μm and 584.0 μm,respectively;the prevalence of high cIMT were 2.5%,4.8%,10.7%and 44.2%,respectively),FMP(cIMT levels were 538.8μm,542.9 μm,550.6 μm and 584.5 μm,respectively;the prevalence of high cIMT were 3.5%,5.5%,8.2%and 47.0%,respectively),SFM(cIMT levels were 535.6 μm,542.2μm,550.5μm and 586.3 μm,respectively;the prevalence of high cIMT were 2.4%,4.2%,11.1%and 44.8%,respectively)and VFM(cIMT levels were 537.6 μm,539.3μm,552.7 μm and 586.8 μm,respectively;the prevalence of high cIMT were 2.5%,4.7%,10.6%and 46.8%,respectively),all P<0.05.After adjusting for potential covariates,compared with those with lower FMI,participants with higher FMI(OR=2.67,95%CI:1.16-6.15)and those with high FMI(OR=10.67,95%CI:4.7523.98)were all associated with an increased likelihood of high cIMT.Compared with those with lower FMP,participants with high FMP(OR=8.59,95%CI:4.31-17.11)were associated with an increased likelihood of high cIMT.Compared with those with lower SFM,participants with higher SFM(OR=2.63,95%CI:1.19-5.80)and those with high SFM(OR=8.96,95%CI:4.02-19.96)were all associated with an increased likelihood of high cIMT.Compared with those with lower VFM,participants with higher VFM(OR=2.24,95%CI:1.01-4.98)and those with high VFM(OR=9.67,95%CI:4.33-21.57)were all associated with an increased likelihood of high cIMT.RCS analysis showed a linear dose-response relationship between the elevated levels of FMI and SFM and high cIMT(all P for non-linear>0.05),and showed a nonlinear dose-response relationship between the elevated levels of FMP and VFM and high cIMT(all P for non-linear<0.05).2.The efficacy of different obesity indices in screening high cIMTThe AUC and 95%CIs of BMI-Z score,WC-Z score,WHtR-Z score,FMI-Z score,and FMP-Z score for screening high cIMT were 0.86(0.84-0.89),0.86(0.830.88),0.84(0.81-0.87),0.85(0.82-0.88),and 0.84(0.81-0.87),respectively.The OR and 95%CIs of the Z-scores for the five obesity indices were 3.79(2.88-4.98),3.50(2.66-4.61),2.86(2.29-3.57),3.14(2.46-4.01),and 3.21(2.47-4.18)for high cIMT,respectively.The AUC and 95%CIs of obesity status defined by the above five indices(i.e.,BMI,WC,WHtR,FMI,and FMP)for screening high cIMT were 0.76(0.73-0.79),0.77(0.74-0.80),0.76(0.73-0.79),0.78(0.75-0.82),and 0.79(0.76-0.82),respectively.The OR and 95%CIs of obesity status defined by the above five indices were 4.78(2.87-7.96),4.71(2.92-7.60),5.23(3.49-7.84),5.57(3.65-8.52),and 6.89(4.54-10.45)for high cIMT,respectively.These results suggested that five different obesity indices(i.e.,BMI,WC,WHtR,FMI,and FMP)have similar screening efficacy for high cIMT in children.Conclusions1.Elevated levels of FMI,FMP,SFM,and VFM were all positively associated with the increased cIMT levels and the likelihood of high cIMT.There was a linear dose-response relationship between the elevated levels of FMI and SFM and high cIMT,and there was a non-linear dose-response relationship between the elevated levels of FMP and VFM and high cIMT.2.The efficacy of BMI,WC,WHtR,FMI,and FMP in screening high cIMT was equivalent. |
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