Relation of body mass index (BMI) to the prevalence of hypertension in children: A 3years' school-based prospective study in Suzhou, China.

Background: The prevalence of hypertension has been increasing in children and adolescents in China, which is considered to be accompanied with the epidemic of childhood overweight and obesity, but limited prospective studies have investigated the effect of body mass index (BMI) change on blood pressure among children, especially in China.

Methods: This school-based prospective study compared the blood pressure and prevalence of hypertension in students with different patterns of change in BMI between two periods (childhood and adolescence). 5465 children were followed-up since 2011(childhood) in Suzhou, China and had weight, height and blood pressure measured in 2011(childhood) and 2014(adolescence).

Results: Those who changed from being overweight in childhood to having normal BMI in adolescence had similar mean blood pressures to those who had a normal BMI at both two periods. In contrast, those who were overweight at both two periods or who had a normal BMI in childhood and were overweight in adolescence had higher blood pressure in adolescence than those who had a normal BMI at both two periods. Compared with students who had a normal BMI at both periods, those with combination of abnormal BMI in childhood and adolescence have higher ORs of hypertension (4.83 in boys, 3.44 in girls and 3.73 in total).

Conclusion: These results suggest that obesity is a key determinant of blood pressure during childhood, and weight reduction may have important beneficial effects on blood pressure.