Boys who become overweight during puberty are more likely to be diagnosed with heart failure when they grow up than their slimmer counterparts, according to new research being presented at this year's European Congress on Obesity (ECO) in Vienna, Austria (23-26 May). However, boys who are overweight as children and manage to shed the pounds and achieve a healthy body mass index (BMI) during puberty do not appear to be at increased risk of heart failure as adults.
This population-based study in Gothenburg, Sweden identifies BMI change during puberty as a potential novel risk factor for adult heart failure in men, and highlights the importance of maintaining a healthy body weight throughout life.
Heart failure--when the heart is too weak to pump blood around the body properly--affects around 26 million adults worldwide (compared to about 32 million who are living with cancer). The prognosis for people with heart failure is worse than those than that of many common forms of cancer. It is well established that weight gain during middle-age contributes to increased risk of heart failure. Previous research has also suggested a link between high BMI in young adulthood and adult heart failure in men, but it is unclear whether childhood BMI or changes in BMI during puberty alter this risk.
In this study, Dr Maria Bydgell from the University of Gothenburg and colleagues analysed the health records of over 37,600 boys born between 1945 and 1961 who were followed until the end of 2013, to examine how BMI in childhood and BMI change during puberty are associated with heart failure in adulthood. BMI (body weight relative to height) at age 8 years and BMI during puberty (calculated as BMI at age 20 minus BMI at age 8) were obtained from paediatric growth charts and mandatory military conscription examinations.
During an average 37.7 years of follow-up (after age 20), 342 men were admitted to hospital with heart failure, with an average age at diagnosis of 53.2 years. The researchers adjusted for factors that could affect the risk of heart failure including birth year and country of birth.
Analyses showed that boys who were normal weight at 8 years of age and became overweight during puberty were three times more likely to be diagnosed with heart failure as adults than boys who weren't overweight as children or during puberty (2.2% participants who were normal weight during childhood and overweight at age 20 [BMI above 25 kg/m2] vs 0.8% participants who were normal weight at both 8 and 20 years of age). There was no association between being overweight in childhood and heart failure.
The researchers also found that the risk of heart failure increased with increasing BMI change during puberty. Boys in the upper quartile of BMI change during puberty were more than twice as likely to develop heart failure as adults compared to those with a BMI change in the lower quartile.
The authors conclude: "A sustained obesity epidemic could offset the current trend of declining cardiovascular death rates. Our findings emphasise the importance of maintaining a healthy weight from an early age. Given that heart failure is on the rise in young adults, more action needs to be taken worldwide to curb the growing obesity epidemic."
They add: "It's important to emphasise that our findings do not suggest that everyone who is overweight during puberty will go on to develop heart failure in later life."
This is an observational study, so no firm conclusions can be drawn about cause and effect and the authors point to several limitations, including that no information on childhood socio-economic factors or education was available for the men in the study born in 1945-61. They also note that they were unable to control for several important risk factors (e.g. smoking and exercise) or for BMI at middle age. Finally, as Sweden did not have mandatory female military conscription at the time, they were unable to retrieve young adult BMI for women, so it was not possible to determine sex-based differences in the association between BMI change during puberty and adult risk of heart failure.