That was the key finding from a study led by Tokyo's National Research Institute for Child Health and Development, and the University of Tokyo.
Based on hospital discharge records from a national Japanese database of 38,679 inpatients between the ages of three and eight who had been diagnosed with asthma, the researchers sought to explore the impact of obesity on children hospitalised with acute asthma exacerbation.
They classified the patients into four categories based on BMI and age: underweight (3,177), normal weight (28,904), overweight (3,334) and obese (3,264).
They then compared 30-day re-admission, intensive care requirement, average total hospitalisation costs, and hospital stay duration between the four groups.
They found that among the obese patients, the 30-day re-admission rates were higher, and they tended to stay hospitalised for longer than patients of normal weight, for an avearge of 0.12 days.
Of the obese children, 3.6% had to be re-admitted. The percentage was 3.1% among overweight children and 3.2% among underweight children; paediatric asthma patients of normal weight had the lowest re-admission rate at 2.9%.
This was consistent with previous studies that had linked obesity to heightened severity of illness in asthma patients.
This led the researchers to write that "obese children require more attention and greater treatment to control their asthma after discharge from hospital".
They wrote: "These differences in length of hospital stay may reflect the difficulty and complexity of procedures such as airway management, complications, and greater severity of the illness."
They added that "no significant difference was observed between the four groups regarding the need for intensive care, and total hospitalisation costs".
They attributed this inconsistency to several factors, such as differences between Japan and the US in terms of healthcare access, the adherence of long-term treatment, and the severity of obesity and asthma.
They concluded: "Paediatric obesity was significantly associated with an increased risk of 30-day re-admission for Japanese children hospitalised with acute asthma exacerbation.
"Our investigations provide important information for the prevention of obesity in children with asthma."
Source: Pediatric Allergy and Immunology
"Impact of pediatric obesity on acute asthma exacerbation in Japan"
Authors: Yusuke Okubo, et al.