Asthma, allergic rhinitis associated with risks for mycobacterial disease
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Key takeaways:
- Mycobacterial disease incidence was significantly higher among patients with vs. without allergic disease.
- Asthma and allergic rhinitis increased this risk, whereas atopic dermatitis did not.
Patients with asthma or allergic rhinitis had greater risk for mycobacterial disease than patients who did not have these allergic diseases, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
Age and BMI had significant effects on this relationship between allergic and mycobacterial disease as well, Taehee Kim, MD, of the division of pulmonary, allergy and critical care medicine in the department of internal medicine at Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine in Seoul, South Korea, and colleagues wrote.
The researchers extracted data from the Korean National Health Insurance Service database for 593,018 patients with allergic disease (mean age, 50.1 years; 43.4% men), defined as atopic dermatitis, asthma or allergic rhinitis, and 3,245,662 patients who did not have allergic disease (mean age, 46.5 years; 56.5% men).
During a median follow-up of 8.3 years (interquartile range, 8.1-8.6 years), 23,932 patients (0.6%) were diagnosed with mycobacterial diseases, including tuberculosis and nontuberculosis mycobacteria (NTM).
Incidences of mycobacterial diseases included one per 1,000 person-years (n = 4,613) in the group with allergic diseases and 0.7 per 1,000 person-years (n = 19,319) in the group that did not have allergic diseases (P < .001).
Compared with the patients who did not have allergic disease, patients with allergic disease had an adjusted hazard ratio of 1.13 (95% CI, 1.1-1.17) for mycobacterial disease, with adjusted hazard ratios of 1.38 (95% CI, 1.25-1.53) for NTM and 1.11 (95% CI, 1.07-1.15) for tuberculosis.
Specifically, risks for mycobacterial diseases increased with asthma (adjusted HR = 1.37; 95% CI, 1.29-1.45) and allergic rhinitis (aHR = 1.07; 95% CI, 1.04-1.11) but not with atopic dermatitis (aHR = 1.11; 95% CI, 0.93-1.32). Risks for tuberculosis and NTM infection with each allergic disease were similar, the researchers found.
Patients with one allergic disease had an adjusted hazard ratio of 1.12 (95% CI, 1.08-1.16) for developing a mycobacterial disease. Patients with two allergic diseases had an adjusted hazard ratio of 1.26 (95% CI, 1.16-1.36).
The adjusted hazard ratio was 1.43 (95% CI, 0.81-2.51) for patients with three allergic diseases, although the researchers did not call this increase in adjusted hazard ratio statistically significant.
Tuberculosis had a similar pattern, results showed, with adjusted hazard ratios of 1.09 (95% CI, 1.06-1.14) for one allergic disease, 1.23 (95% CI, 1.13-1.34) for two diseases and 1.42 (95% CI, 0.78-2.56) for three diseases.
The pattern for NTM infections was not similar, the researchers continued, with adjusted hazard ratios of 1.37 (95% CI, 1.23-1.53) for one allergic disease, 1.43 (95% CI, 1.14-1.81) for two diseases and 1.24 (95% CI, 0.18-8.84) for three diseases.
There was no significant interaction between allergic diseases and risk for mycobacterial disease based on sex or smoking, but age and BMI did have significant impacts on these associations. Adjusted hazard ratios for mycobacterial disease with allergic disease included 1.18 (95% CI, 1.12-1.24) for patients aged 65 years and older and 1.3 (95% CI, 1.21-1.38) for patients with a BMI of 25 kg/m2 and higher.
These associations between age (P = .002) and BMI (P < .001) were greater for allergic disease and tuberculosis specifically, with no difference based on sex or smoking status.
However, the researchers found no differences in associations between allergic diseases and NTM infection based on age, sex, BMI or smoking status.
Based on these findings, the researchers concluded that there was an association between allergic diseases and increased risks for mycobacterial disease, with significant hazards for patients with asthma and allergic rhinitis but not for patients with atopic dermatitis, in addition to significant effects with age and BMI.
The researchers called for future studies with larger populations, including consideration of the role of immunosuppressants. Also, the researchers said clinicians should be more aware of these risks and consider further evaluation of mycobacterial infections when patients with allergic diseases have unexplained symptoms despite appropriate care.
Perspective
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The aim of this study — which was conducted in South Korea and included more than 3 million individuals from 2009 through 2018 — was to evaluate the potential risks of mycobacterial infections, including tuberculosis and NTM infections, among atopic patients. To this point, there has been conflicting data regarding a possible correlation (or lack of correlation) of individuals with atopic disease and mycobacterial infection. South Korea has a high incidence of tuberculosis-related deaths and has been experiencing an increase in NTM infections, which is why it was chosen for this study.
Only 0.6% of those patients developed mycobacterial disease, with the atopic cohort experiencing more mycobacterial disease than the cohort without allergic disease. The risks were higher among older adults and those with obesity. Asthma and allergic rhinitis carried higher risks for development of mycobacterial infections, whereas atopic dermatitis did not in this study.
There was some speculation in the discussion of this article that suggested mycobacterial infections may be more common among those with obesity due to their potential for more severe allergic rhinitis and asthma. Also, older individuals and those with obesity may be at risk due to their possibly higher need for immunosuppressive medications such as steroids. Unfortunately, this study did not evaluate if any patients were on concomitant immunosuppressive medications such as steroids.
There was also discussion about whether IL-4 and IL-17 are involved in both allergic disease and in fighting mycobacterial infections, and the correlation between the two may lie within there. The overarching suggestion in this article is that impaired immune function in patients with asthma and allergic rhinitis may make individuals more susceptible to mycobacterial infections.
From this study, this article suggests that patients with asthma and bronchiectasis may be a specific population to have a higher concern for underlying mycobacterial infections, especially if these patients are not adequately responsive to standard treatment.
Because this study was a retrospective study of South Korean patients who appear to have a higher population risk for mycobacterial infections, in general, I am curious what results this study would have obtained in the United States, where mycobacterial disease is less common. With that being said, I do believe that it is an important possible association that I do not think I have considered closely in my clinical practice.
Although I have not personally encountered a patient with tuberculosis in my clinical practice, I have had several patients with NTM infections. I do not know if I have specifically considered a possible higher risk for developing mycobacterial infections among my patients with asthma or allergic rhinitis. Perhaps this is something I could consider more in the future when I encounter such patients with significant respiratory symptoms that are not responding to traditional therapies.
Clinicians should carry with them a vast differential for their patients. Awareness of a possible link between mycobacterial infections in patients with asthma and allergic rhinitis would be the first step. Having this in the back of one’s mind, especially if encountering a patient where mycobacterial infections are more common, should be considered when treating these patients.
A better understanding of this potential risk in areas where mycobacterial infection is less common such as the United States would be important and relevant to those who practice in these areas. There would be benefit if there was some more in-depth evaluation if any of the patients in this study had an underlying immunodeficiency or use of immunosuppressive therapies.
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