Children and adolescents who are overweight or obese are more likely to have asthma than their healthy weight counterparts, according to a new Kaiser Permanente Southern California study published in the online edition of Obesity. The study, which included more than 681,000 children between ages 6 and 19, found that the association between asthma and body mass index varied by race and ethnicity.

The study found that the association between BMI and asthma was weaker for African Americans, a group that was previously known to have the highest prevalence of asthma, than for youth from other racial and ethnic groups. Researchers found the strongest association between BMI and asthma in Hispanic youth.

"This research contributes to the growing evidence that there is a relationship between childhood obesity and asthma, and suggests that factors related to race and ethnicity, particularly for Hispanic youth, may modify this relationship," said study lead author Mary Helen Black, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation. "The study's large and diverse population, which is broadly representative of the Southern California region, allowed us to examine a wide range of BMI categories in relation to asthma among youth from five racial/ethnic groups."

Researchers also found that, among youth with asthma, being overweight or obese was associated with more frequent visits to the doctor or emergency department for asthma. In addition, overweight or obese youth with asthma used more inhaled and oral corticosteroid asthma drugs, when compared to healthy weight youth. The need for these medical treatments could have broader health implications as other studies have suggested a link between these medications and type 2 diabetes.

The cross-sectional, population-based study included youth from a racially and ethnically diverse population. Asthma was fairly common in this population, affecting about 18 percent of the youth in the study. Researchers used electronic health records to obtain height and weight measurements, asthma diagnoses, and dispensed prescriptions for asthma-specific medications for children and adolescents in the Kaiser Permanente Southern California integrated health plan from 2007 to 2009.

This study is part of the Kaiser Permanente Southern California Children's Health Study, and their ongoing work to better understand and prevent childhood obesity. Last year, the KPSC Children's Health Study found that 7 percent of boys and 6 percent of girls ages 2 to 19 in the population were extremely obese. This study also has used electronic health records to determine that children who were obese or overweight have a significantly higher prevalence of psoriasis, a chronic inflammatory disease of the skin.