Men, Smokers More Likely to Have Undiagnosed Asthma, According to Study

The underdiagnosis of asthma could be due in part to patient characteristics that increase the likelihood of underreporting asthma symptoms or inaccurate evaluation by care providers, according to findings of a study published in the Journal of Asthma and Allergy. The investigators aimed to identify factors related to asthma underdiagnosis by comparing study participants with symptoms of asthma and no diagnosis vs those with symptoms and a diagnosis of asthma.

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

The questionnaire was based on validated questions from the European Community Respiratory Health Survey. Whereas the international questionnaire had 27 questions on it, the version used in Sweden had an additional 13 questions, which covered aspects such as education level, physical activity, and sleep disturbances. The 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 whistling in your chest at any time in the past 12 months?” “Have you been at all breathless when the wheezing noise was present?” and “Have you had this wheezing or whistling when you did not have a cold?” An asthma diagnosis 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. Level of physical activity, 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.

Participants were also categorized into 3 groups by smoking status: current smoker, former smoker, and never smoker. This was based on questions asking if a participant had smoked in the last month and if they had ever smoked for as long as a year. Education level was divided into 3 groups: elementary education, high school education, and university degree.

Some chronic diseases that participants reported in the survey included nocturnal asthma-like symptoms, symptoms of disturbed sleep, diabetes and hypertension, chronic rhinosinusitis, and allergic rhinitis. Risk factors for not receiving a diagnosis of asthma were analyzed via multivariable analysis adjusting for age, gender, smoking history, BMI, and study center.

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

The association between not having an asthma diagnosis and current smoking was stronger in men than in women (adjusted odds ratio [aOR], 3.49 [95% CI, 2.13-5.74] vs 2.81 [95% CI, 1.52-3.12]; P_interaction = .02). The association between low educational level and not being diagnosed was only found in men (men: aOR, 1.88; 95% CI, 1.06-3.31; women: aOR, 1.15; 95% CI, 0.74-1.80; P_interaction = .04). Men with asthma symptoms were almost 50% more likely to lack a diagnosis of asthma than women with similar symptoms.

The researchers noted that there were possible medical explanations for the lack of asthma diagnosis in these specific groups. According to the literature, asthma is more common in women than in men, which may lead to oversight of asthma diagnosis in men. Current smokers may have attributed their asthma symptoms to the fact that they smoke. Participants without a diagnosis of asthma but with a diagnosis of hypertension may have asthma symptoms due to adverse effects of some hypertension medicines.

This study had some limitations to its analysis. It used answers to a questionnaire, which can lead to over- or underreporting of symptoms of asthma. In the questionnaire, the diagnosis of asthma was based on 1 question, whereas 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 did not have any information about the onset or duration of the participants’ symptoms of asthma. Lastly, only 56.0% of the questionnaires sent out were returned to the authors of the study, which could lead to selection bias in the results.

The study concluded that men, elderly participants, smokers, and participants with lower educational levels had a lower prevalence of diagnosed asthma despite reporting asthma-related symptoms.

“The results may partly be explained by a higherprevalence of other disorders that cause respiratory symptoms in these populations and indicate that underdiagnosis ofasthmamightbemoreprevalentinthesegroups,” wrote the researchers.

Reference

Kisiel MA, Jacobsson M, Järhult S, et al. Risk factors for the absence of diagnosis of asthma despite disease symptoms: results from the Swedish GA²LEN study. J Asthma Allergy. 2022;15:179-186. doi:10.2147/JAA.S350245