Obesity accounts for around a quarter of breathlessness symptoms in Australian adults, a study from the Woolcock Institute of Medical Research has found.
And given the continuing increase in prevalence of obesity both in Australia and globally, the findings have important implications for health policy and clinical practice according to the investigators including Professor Helen Reddel.
The cross-sectional study [link here] involved 9769 Australian adults who had completed the National Breathlessness Survey. Breathlessness was defined by the researchers as modified Medical Research Council dyspnoea scale grade ≥2 and BMI was calculated from self-reported height and weight.
Overall, 51% of the study participants were female; 44% were aged ≥50 years; 16% were daily smokers and 27% ex-smokers; and 32% were overweight, with an additional 28% classified as obese.
Results showed that obesity accounted for 22% of breathlessness symptoms in men and 28% in women. After adjustment for age, obese participants were more than twice as likely to have clinically important breathlessness than non-obese participants and obesity contributed to almost 25% of breathlessness.
“These estimates were robust to adjustment for the presence of various common medical conditions known to contribute to breathlessness, such as cardiovascular, respiratory, and mental health conditions,” the study authors wrote in their paper published in Respirology. (link here)
Indeed, after considering the potential confounding effect of asthma, COPD, ischaemic heart disease, current back pain or arthritis, and anxiety or depression the adjusted PAF* of obesity for breathlessness remained around 21% for the overall population, 24% for women, and 19% for men.
The study authors noted that National Health Surveys conducted in 2007–2008, 2011–2012, 2014–2015, and 2017–2018 estimated the prevalence of obesity as 17.5%, 23.2%, 27.9%, and 31.3%, respectively.
“Our findings therefore suggest that the attribution of obesity to breathlessness could have almost doubled in 10 years. If this trend continues, and the aRR remains constant, a higher percentage of people in Australia will suffer from breathlessness related to obesity in the foreseeable future,” they warned.
They said there were a number of potential mechanisms that might explain the observed relationship between obesity and breathlessness, for example obesity may affect both respiratory and cardiovascular systems.
The authors noted several limitations of the study including that weight and height were self-reported and the cross sectional nature of the study meant the observed relationship between obesity and breathlessness could be bidirectional.
*The population attributable fraction (PAF )is a widely used epidemiologic measure defined as the fraction of all cases of a particular condition in a population that is attributable to a specific risk factor.