Research published ahead of print in Thorax reports that women with a large waist are more likely to develop asthma even if they have a normal body weight. In addition, US researchers established a link between excess weight and asthma severity and occurrence.

Obesity is a risk factor for adult asthma, especially in women. However, few studies have considered the connection between large waist size (abdominal obesity) and asthma.

A team of scientists from The Northern California Cancer Center’s Berkeley led a group of researchers from California. They used data from the California Teachers Study, which began in 1995. This included 133,479 female teachers and school administrators. All were either employed in the California public school system or retired and receiving retirement benefits.

The participants answered successive questionnaires (in 1995, 1997, 2000 and 2005).

After analyzing 88,304 women, results showed that 13 percent of them (11,500 women) were obese in 1995, including 1,334 who were extremely obese.

Several groups of women were studied: those with adult onset asthma, and those with adult onset asthma who were not overweight at age 18.

Findings pointed out that women who were obese were more than twice as likely to have adult onset asthma, and extremely obese women were more than three times more likely to have asthma, compared with women of normal weight or body mass index (BMI) below 25.

In addition, the researchers found that a large waist circumference of more than 88 cm was linked with increased asthma incidence even among women with a normal BMI.

According to emergency medical visits and hospital admissions, women who were obese and overweight were at greater risk of severe asthma attacks.

The authors explain: “All measures of obesity were strongly associated with increased asthma prevalence. Even being modestly overweight was associated with higher asthma prevalence in this population.”

They added that a large waist circumference was also linked with some increased asthma prevalence among women who were of normal weight based on BMI.

The researchers write in conclusion: “These findings are particularly troubling because a majority of American adults are now overweight or obese. The current prevalence of obesity in US adults is estimated at 32% and the prevalence of overweight and obesity combined is 66%.”

“Abdominal obesity is increasing faster than overall obesity. According to an analysis of data from the 2003 – 4 National Health and Nutrition Examination Survey, 61% of US women were abdominally obese based on waist circumference.”

“Obesity, waist size and prevalence of current asthma in the California Teachers Study cohort”
J Von Behren, M Lipsett, P L Horn-Ross, R J Delfino, F Gilliland, R McConnell, L Bernstein, C A Clarke, P Reynolds
doi:10.1136/thx.2009.114579
Thorax

Written by Stephanie Brunner (B.A.)