Association between anthropometric markers and asthma control, quality of life and pulmonary function in adults with asthma

Background The role of abdominal fat and body fat (BF) in the evaluation of nutritional status in asthma has been considered recently. The present study aimed to evaluate the association between different anthropometric markers and asthma control, pulmonary function and quality of life. A secondary objective was to determine the agreement between the anthropometric markers with respect to assessing obesity in adults with asthma. Methods This cross-sectional study enrolled adult asthma patients attending an outpatient asthma clinic in southern Brazil. Patients were evaluated regarding sociodemographic data, lung function, asthma control, nutritional status and health-related quality of life (Asthma Quality of Life Questionnaire; AQLQ). Nutritional status was classified by body mass index (BMI), waist circumference (WC) and BF. Results The mean (SD) age of the 198 patients was 56.2 (14.8) years. The prevalence of uncontrolled asthma among subjects who were overweight as diagnosed by their BMI was 64.6% higher than in those who were normal weight. An increase in a measure of BMI (1 kg m(-2)) decreases approximately 44-59% of symptoms, activity limitations and emotional function domains of the AQLQ, whereas an increase in a measure in WC (1 cm) decreases approximately 24-30% of the same domains. Agreement between BMI and BF was 0.566 and that between BMI and WC was 0.597 by Kendall's Tau-b test. Conclusions The prevalence of uncontrolled asthma is greater in overweight subjects than in normal weight subjects. WC and BMI were negatively associated with symptoms, activity limitations and emotional function domains of the AQLQ. BMI appears to be sufficient to diagnose the nutritional status of subjects with asthma in this population.