BMI can influence adult males’ and females’ airway hyperresponsiveness differently

Abstract

Background: Epidemiological data indicate that obesity is a risk factor for asthma, but scientific literature is still debating the association between changes in body mass index (BMI) and airway hyperresponsiveness (AHR). Methods: This study aimed at evaluating the influence of BMI on AHR, in outpatients with symptoms suggestive of asthma. 4,217 consecutive adult subjects (2,439 M; mean age: 38.2±14.9 yrs; median FEV1 % predicted: 100 [IQR:91.88-107.97] and FEV1/FVC % predicted: 85.77% [IQR:81.1-90.05]), performed a methacholine challenge test for suspected asthma. Subjects with PD20 < 200 or 200 < PD20 < 800 or PD20 > 800 were considered affected by severe, moderate or mild AHR, respectively. Results: A total of 2,520 subjects (60% of all cases) had a PD20 < 3,200 μg, with a median PD20 of 366 μg [IQR:168–1010.5]; 759, 997 and 764 patients were affected by mild, moderate and severe AHR, respectively. BMI was not associated with increasing AHR in males. On the contrary, obese females were at risk for AHR only when those with moderate AHR were considered (OR: 1.772 [1.250-2.512], p = 0.001). A significant reduction of FEV1/FVC for unit of BMI increase was found in moderate AHR, both in males (β = −0.255; p =0.023) and in females (β = −0.451; p =0.017). Conclusions: Our findings indicate that obesity influences AHR only in females with a moderate AHR level. This influence may be mediated by obesity-associated changes in baseline lung function.

Obesity can influence children’s and adolescents’ airway hyperresponsiveness differently

“…The risk evaluation in the two sexes showed that it was 38% greater in females when compared to males. This means that obesity influences only female adolescents and not male adolescents or children, which is perfectly in line with what was assessed in another study of ours [20] and in previous researches [23,25,26] where a higher AHR risk was observed only in adult females. Female adolescents become adults more precociously than males.…”

“…This means that a BMI increase determines functional alterations consistent with an obstructive pattern in female adolescents. This is in accordance with a previous study of ours, carried out on adults, where we found a significant reduction of FEV 1 /FVC ratio only in females with moderate AHR [20]. Also other researchers found a FEV 1 /FVC reduction both in obese children [6] and adults [36], though this was not confirmed by other authors [32,37].…”

“…Another controversial issue is the different role of BMI with regard to gender. In fact, some authors found that a higher BMI was related to a higher PC 20 (a lower airway reactivity) in female children but not in males [6]. On the contrary, Huang et al noted a decreased prevalence of AHR in the lowest quintile of BMI in teenage girls [10].…”

“…Besides, studies often associate children with adolescents, without taking into account that puberty can influence asthma differently [19]. Also smoking can have a negative impact on bronchial hyperreactivity [20].…”

The relationship between body mass index and increased airway reactivity based on methacholine challenge test results

“…A survey in 2012 was conducted on 200 patients (100 obese men and 100 non-obese men). The results of this qualitative study illustrated that in obese people, there are different reductions in respiratory function that is due to a decrease in chest expansion power and limitation in increasing the volume of the chest cavity and consequently reduction in respiratory volume and total lung volume reduction [ 16 ].…”