Obesity is a known risk factor for the development of asthma and obese asthmatics are prone to be severe and poorly controlled. Obesity is also associated with increased risk of various metabolic diseases but recent studies suggested that not all obese subjects are at increased risk of such diseases and the ‘metabolically healthy obese’ (MHO) phenotype may exist in the absence of metabolic abnormalities. Due to the paucity of data regarding asthma-related outcomes of obese asthmatics according to their metabolic status, we aimed to investigate the differences between MHO and metabolically unhealthy obese (MUO) asthmatics in terms of asthma-related clinical outcomes.
Materials and Methods
A total of 206 patients who were diagnosed with asthma in Asan Medical Center asthma cohort from June 2005 to Mar 2013 were subject to analysis, after sorting out patients whose BMI were ≥25. We divided these patients into two groups, MHO asthmatics (n=106) and MUO asthmatics (n=100), referring to the NCEP ATP III identification of the metabolic syndrome. Then we compared asthma-related clinical characteristics between these two groups.
The patients in MUO asthma group had older age (60.9 ±10.3 vs 54.7 ±13.6, p-value <0.001) and lower FEV1 % predicted (79.2 ±20.9 vs 73.0 ±19.6, p-value= 0.03) compared with MHO asthmatics. Also, MUO asthmatics had higher frequency to develop severe persistent asthma (20.7 % vs 36.0 %, p-value= 0.02). Moreover, MUO asthma group showed lower mean FEV1 % predicted value for 1year and 3years follow-up after enrollment and used higher mean ICS dosage compared at 3 years after enrollment.
Obese asthmatics demonstrated different clinical characteristics according to their metabolic status, as MUO asthmatics were older with lower pulmonary function and higher tendency to develop severe asthma at enrollment and longitudinal follow-up. This study suggests that different therapeutic approach should be implemented for obese asthma patients according to subtype of obesity.