Cardiovascular morbidity, diabetes and cancer risk among children and adolescents with severe obesity

Abstract

Severe obesity among children and adolescents is a significant global public health concern. The prevalence has markedly increased over the last decades, becoming common in many countries. Overwhelming rates of obesity among youth have prompted efforts to identify an evidence-based immediate- and long-term cardiometabolic risk factor profile in childhood-onset severe obesity, and to highlight gaps that require further investigation. The PubMed database was systematically searched in accordance with PRISMA guidelines. The search yielded 831 results, of which 60 fulfilled stringent criteria and were summarized in this review. The definition of severe obesity was variable, with only one half the publications using the definition BMI > 120% of the 95th percentile. Point estimates of the prevalence of at least one cardiometabolic risk factor in children with severe obesity reportedly range from 67 to 86%. Cross-sectional studies indicate that children and adolescents with severe obesity are at greater risk than those with mild obesity for type 2 diabetes, hypertension, fatty liver disease and dyslipidemia, already at childhood and adolescence. Robust epidemiological data on the long-term risk and actual point estimates in adulthood are lacking for these diseases as well as for other diseases (coronary heart disease, stroke, chronic kidney disease and cancer). Recent longitudinal studies indicate an increased risk for cardiomyopathy, heart failure, cardiovascular mortality and all-cause mortality in adulthood for adolescents with severe obesity compared to those with mild obesity. Given the alarming increase in the prevalence of severe obesity, the persistence of adiposity from childhood to adulthood and the precarious course of young adults with chronic comorbidities, the economic and clinical services burden on the healthcare system is expected to rise.

Keywords: Adolescence; Cancer; Cardiovascular; Diabetes; Hypertension; Morbid obesity; Mortality; NAFLD; Paediatrics; Severe obesity; Youth.

Fig. 1

Study flowchart

Fig. 2

Commonly used definitions for childhood severe obesity. AMA: American Medical Association; HRSA: Health Resources and Services Administrations; CDC: Centers for Disease Control; AHA: American Heart Association; NHANES: National Health and Nutrition Examination Survey. *Age-specific and sex-specific BMI. The table shows characteristics of commonly used definitions. The chart presents the distribution of the use of the definitions by year of publication

Fig. 3

Prevalence of abnormal cardiometabolic risk factors by BMI group in cross-sectional studies. TC: total cholesterol; LDL: low-density lipoprotein cholesterol; HDL: high-density lipoprotein cholesterol; TG: triglycerides; BP: blood pressure; SBP: systolic blood pressure; DBP: diastolic blood pressure; FG: Fasting Glucose; HbA1c: haemoglobin A1c. A single panel under BP represents abnormal values of SBP or DBP. Abnormal values of fasting plasma glucose (≥ 100 mg/dl) and glycated hemoglobin (> 5.7%) are those recommended by the American Diabetes Association for identifying persons at high risk for diabetes (at least in the prediabetes range). Studies based on cohorts from the United States (a) and other countries (b) are presented. The definition of severe obesity varied between studies, as did the thresholds that defined abnormal values of cardiometabolic morbidity (Additional file 1: Table S2)

Fig. 4

Cardiometabolic outcomes in adulthood of adolescents with severe versus mild obesity in national longitudinal cohorts. CHD: coronary heart disease; CVD: cardiovascular disease. Severe obesity and mild obesity were defined as BMI ≥ 35 and 30 ≤ BMI < 35 kg/m², respectively. Cox proportional hazard models were used in all the studies. The horizontal axis is presented in the logarithmic scale. * The presented numbers of cases and participants were derived from the unadjusted models. †Swedish national cohort. Heart failure was determined as the first event of heart failure hospitalization. The reference groups were 18.5 < BMI < 20.0 kg/m². Hazard ratios (HRs) were adjusted for age at entrance to the study, the year of entrance to the study, test center, comorbidities at baseline, parental education, systolic and diastolic blood pressure, muscle strength and fitness. HRs for heart failure were also adjusted for IQ level. HRs for cardiomyopathy were also adjusted for alcohol and substance use disorder. ‡Israeli national cohort. The reference group was 17.5 < BMI < 20.0 kg/m². HRs were adjusted for age, birth year, sex, socioeconomic status, country of origin, education level and height