Men and smokers more likely to have undiagnosed asthma, study finds

According to the results of a study published in the Asthma and Allergy Diary. The researchers aimed to identify factors related to underdiagnosis of asthma by comparing study participants with asthma symptoms and no diagnosis to those with both symptoms and a diagnosis of asthma.

This cross-sectional study was based on the Global Allergy and Asthma Global Network (GA2LEN) Survey conducted in 2008. As part of the survey, a questionnaire was sent by post to 45,000 adults aged 16-75 in 4 Swedish cities. The current analysis assessed 25,391 participants with complete data for relevant variables. Participants who reported a diagnosis of asthma without asthma symptoms, participants with chronic obstructive pulmonary disease (COPD), and participants who did not answer questions about COPD were excluded from this study, leaving a population of 22,873 people.

The questionnaire was based on validated questions from the European Community Lung Health Survey. While the international questionnaire had 27 questions, the version used in Sweden had 13 additional questions, which covered aspects such as level of education, physical activity and sleep disorders. Data from the Swedish survey were used in this study.

Asthma-related symptoms were determined by positive responses to all of the following questions: “Have you had wheezing or wheezing in your chest at any time in the past 12 months?” “Did you get short of breath when the wheezing sound was present?” and “Did you have this wheezing or wheezing when you didn’t have a cold?” A diagnosis of asthma was self-reported and determined by a positive response to the question “Have you ever had asthma?” »

Body mass index (BMI) was based on self-reported height and weight. Physical activity level, defined as exercise-induced sweating or shortness of breath, was divided into 3 categories: low, at least once a month; medium, up to 3 times a week; and high, at least 4 times a week.

The participants were also classified into 3 groups according to their smoking status: current smoker, former smoker and never smoker. This was based on questions asking if a participant had smoked in the past month and if they had ever smoked for as long as a year. The level of education was divided into 3 groups: primary education, secondary education and university degree.

Some chronic illnesses reported by survey participants included asthma-like nighttime symptoms, sleep disturbances, diabetes and hypertension, chronic rhinosinusitis and allergic rhinitis. Risk factors for not being diagnosed with asthma were analyzed via multivariate analysis adjusting for age, sex, smoking history, BMI and study center.

Of the 1578 participants who reported asthma-like symptoms, 632 participants (40.1%) had never been diagnosed with asthma. The proportion of men in the group without an asthma diagnosis was significantly higher than in the group with a diagnosis. Participants without a diagnosis of asthma were significantly older, were more often current smokers, had a lower level of education and were more often on antihypertensive treatment. The group without a diagnosis also reported more sleep disturbances, such as difficulty falling asleep, daytime sleepiness and morning awakenings. Alternatively, participants with diagnosed asthma reported more allergic rhinitis and nocturnal chest tightness than the undiagnosed group.

The association between no diagnosis of asthma and current smoking was stronger in men than in women (odds ratio adjusted [aOR]3.49 [95% CI, 2.13-5.74] against 2.81 [95% CI, 1.52-3.12]; Pinteraction = .02). The association between low education and no diagnosis was found only in men (men: ORa, 1.88; 95% CI, 1.06-3.31; women: ORa , 1.15, 95% CI, 0.74-1.80; Pinteraction = 0.04). Men with asthma symptoms were almost 50% more likely to not have an asthma diagnosis than women with similar symptoms.

The researchers noted that there were possible medical explanations for the lack of a diagnosis of asthma in these specific groups. According to the literature, asthma is more common in women than in men, which can lead to an oversight in the diagnosis of asthma in men. Current smokers may have attributed their asthma symptoms to smoking. Participants without a diagnosis of asthma but with a diagnosis of hypertension may experience asthma symptoms due to the adverse effects of certain blood pressure medications.

This study had some limitations to its analysis. It used responses to a questionnaire, which can lead to over-reporting or under-reporting of asthma symptoms. In the questionnaire, the diagnosis of asthma was based on 1 question, while the symptoms of asthma were based on 3 questions, which makes the definition of the diagnosis of asthma weaker in comparison. The authors of this study had no information on the onset or duration of participants’ asthma symptoms. Finally, only 56.0% of the questionnaires sent were returned to the authors of the study, which could lead to a selection bias in the results.

The study concluded that men, older participants, smokers, and participants with low education had a lower prevalence of diagnosed asthma despite reporting asthma-related symptoms.

“The findings may in part be explained by a higher prevalence of other disorders that cause respiratory symptoms in these populations and indicate that asthma underdiagnosis may be more prevalent in these groups,” the researchers wrote. .


Kisiel MA, Jacobsson M, Järhult S, et al. Risk factors for not being diagnosed with asthma despite disease symptoms: results from the Swedish GA2LEN study. J Asthma Allergy. 2022;15:179-186. doi:10.2147/JAA.S350245

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