Does Asthma Status Affect Respiratory Symptoms From Increasing BMI?

An increase in body mass index (BMI) from weight gain is associated with respiratory symptoms and a higher respiratory burden scale score. Moreover, the association between increased BMI and increased symptoms is even stronger in individuals with asthma, for whom increasing BMI results in even higher symptom burden scores.  These were among research findings recently published in BMJ Open Respiratory Research.

The current study built upon previous research showing that higher BMI and occupational exposure to vapors gas, dust, and fumes are associated with respiratory symptoms. In the current study, researchers sought to determine whether a patient’s asthma status or sex would influence (ie, increase or decrease) respiratory symptoms associated with increasing BMI or increased occupational exposure to vapors, dust, gas, and fumes.  The study used a respiratory burden score to measure variations in symptoms over a 5-year period.

Study findings were based on a survey that is a 5-year follow-up of the Telemark study, a population-based survey begun in 2013 of a random sample of 50,000 people in Telemark County, Norway, who received a questionnaire sent in the mail. For the current study, researchers sent all eligible former responders (n=15681) a second questionnaire in 2018, asking whether any of 7 respiratory symptoms had been experienced in the earlier 12 months and inquiring about the use of asthma medication. Individuals who could not be found or failed to provide height and weight figures were excluded, leaving 6350 participants. The researchers calculated a respiratory burden score from self-reported respiratory symptoms, BMI, and frequency of exposure to VGDF at work. They used stratified regression models to assess the relationship between change in the respiratory burden score and changes in BMI and VGDF exposure.

Changes in the respiratory burden score and BMI correlated with a beta (β)-coefficient of 0.05 (95% CI, 0.04-0.07). This correlation did not differ significantly by sex, as shown by β-coefficients of 0.05 (0.03-0.07) for women and 0.06 (0.04-0.09) for men. In participants with asthma, the association was stronger (0.12; 0.06-0.18) than in those without asthma (0.05; 0.03-0.06; P =.011). The link between change in respiratory burden score and change in VGDF exposure provided a β-coefficient of 0.15 (0.05-0.19) and was more strongly associated for men than for women, resulting in coefficients of 0.18 (0.12-0.24) and 0.13 (0.07-0.19), respectively (P =.064). The estimate was comparable between participants with asthma (0.18; –0.02-0.38) and those without (0.15; 0.11-0.19).

Overall, said investigators, with respect to BMI, higher respiratory burden scores from increased BMI were not influenced by the sex of participants, but those with asthma had significantly higher score changes than those without. More frequent VGDF exposure was associated with higher respiratory burden scores, but no statistically significant differences were observed regarding sex or asthma status.

“To our knowledge, a well-recognized and validated respiratory burden score for subjects without asthma or other respiratory diseases is not available,” the authors added. “We developed our score to better describe the burden of respiratory symptoms, including the use of medication, and to reflect a continuum in respiratory symptoms,” they explained.

The main strength of the study was its large sample size taken from the general population. The sizeable loss to follow-up (51%) was a limitation. Another important limitation was the use of self-reported outcomes.

Reference

Klepaker G, Henneberger PK, Torén K, Brunborg C, Kongerud J, Fell AKM. Association of respiratory symptoms with body mass index and occupational exposure comparing sexes and subjects with and without asthma: follow-up of a Norwegian population study (the Telemark study). BMJ Open Respir Res. 2022;9(1):e001186. doi:10.1136/bmjresp-2021-001186