To examine whether clinically applicable anthropometric measures of abdominal adiposity -- waist circumference and waist-to-height ratio ( WHtR ) -- are related to poorer asthma control in adults with uncontrolled asthma controlling for body mass index ( BMI ) , and whether the relationship ( if present ) is explained by gastroesophageal reflux disorder ( GERD ) , sleep quality , or obstructive sleep apnea ( OSA ) or differs by age of asthma onset or sex .