Multiple risk factors drive acute exacerbations in mild asthma
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Key takeaways:
- 6.5% of patients with mild asthma had at least one acute exacerbation in the year after the index date.
- Demographics, lifestyle, comorbidities and health care use all were associated with greater risks.
Even patients with mild asthma sometimes experience acute exacerbations that require visits to the ED or hospitalization, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
But identifying the risk factors for these visits among these patients may guide them toward appropriate preventive therapy, Wansu Chen, PhD, MD, clinical informatics scientist, department of research and evaluation, Kaiser Permanente Southern California, and colleagues wrote.
The retrospective cohort study included 199,010 patients (64% women; mean age, 43.6 years) aged 18 to 85 years with mild asthma, or 74.5% of the asthma population at Kaiser Permanente Southern California. Patients were non-Hispanic white (36.6%), Hispanic (38.3%), Black (12.5%) or Asian/Pacific Islanders (10%).
Also, the cohort included patients who were current smokers (5.3%), patients with overweight (30.3%) or obesity (44.1%) and patients who exercised at least 1 day a week (55.8%).
Criteria for mild asthma included an asthma-coded visit on the index date; no more than one dispensation of an asthma controller and no more than two canisters of short-acting beta agonists (SABA) dispensed during the baseline window; and no more than one exacerbation and no hospitalizations for asthma during the baseline window.
The researchers also defined an acute asthma exacerbation (AAE) as a hospitalization, ED visit or hospital-based observation with asthma or wheezing as the principal diagnosis at discharge or as other specific respiratory conditions as a principal diagnosis with an acute exacerbation or status asthmaticus as a secondary diagnosis in the 12 months following the index date.
Analysis found 6.5% (n = 12,913) had at least one AAE and 0.8% (n = 1,579) had at least two AAEs in the year following their index date. It also identified specific demographic and lifestyle characteristics, comorbidities and health care use and medication exposures that increased risks for AAEs among patients with mild asthma.
Each decade increase in age (adjusted RR = 1.04; 99% CI, 1.02-1.06) and female sex (aRR = 1.19; 99% CI, 1.13-1.15) increased risks for AAEs among patients with mild asthma.
Patients who identified as Black (aRR = 1.18; 95% CI, 1.1-1.27), Hispanic (aRR = 1.13; 99% CI, 1.07-1.27) and Asian/Pacific Islander (aRR = 1.13; 99% CI, 1.04-1.22) also experienced increased risks for AAEs.
Additional demographic and lifestyle risks included participation in Midi-Cal and other state programs (aRR = 1.16; 99% CI, 1.08-1.25), current smoking (aRR = 1.14; 99% CI, 1.03-1.25), having overweight (aRR = 1.18; 99% CI, 1.1-1.26) and having obesity (aRR = 1.42; 99% CI, 1.34, 1.51).
Comorbidity risks included allergic rhinitis (aRR = 1.12; 99% CI, 1.06-1.19), chronic sinusitis (aRR = 1.14; 99% CI, 1.08-1.21) and nasal polyps (aRR = 1.44; 99% CI, 1.12-1.84).
Eosinophil counts were risks as well, including counts between 150 and 299 (aRR = 1.13; 99% CI, 1.06-1.21), between 300 and 499 (aRR = 1.26; 99% CI, 1.17-1.36) and 500 and greater (aRR = 1.42; 99% CI, 1.29-1.57).
Asthma histories included further risks for AAE, such as:
- history of ED visits for asthma or wheezing: aRR = 1.34; 99% CI, 1.22-1.46;
- history of asthma exacerbation: aRR = 1.74; 99% CI, 1.64-1.84;
- allergist asthma visit: aRR = 1.19; 99% CI, 1.03-1.38;
- pulmonologist asthma visit: aRR = 1.27; 99% CI, 1.04-1.55;
- one or more urgent care visits for asthma: aRR = 1.14; 99% CI, 1.06-1.22;
- one asthma visit not with urgent care: aRR = 1.14; 99% CI, 1.07-1.21; and
- two or more asthma visits not with urgent care: aRR = 1.52; 99% CI, 1.37-1.68.
Among medications, SABA increased risks as well, including one dispensation (aRR = 1.1; 95% CI, 1.05-1.16) and two dispensations (aRR = 1.61; 99% CI, 1.5-1.74). Asthma controller medication also is a risk factor (aRR = 1.39; 99% CI, 1.32-1.46).
Other medications that were risk factors included:
- antidepressants: aRR = 1.07; 99% CI, 1.01-1.13;
- antibacterial or antimicrobial agents: aRR = 1.1; 99% CI, 1.04-1.15;
- calcium channel blockers: aRR = 1.06; 99% CI, 1.01-1.12; and
- proton pump inhibitors: aRR = 1.07; 99% CI, 1.01-1.14.
Protective factors against AAE included exposure to insulin (aRR = 0.83; 99% CI, 0.73-0.94) and metformin (aRR = 0.91; 99% CI, 0.84-0.99).
Noting that unfavorable outcomes may follow improper management of mild asthma, the researchers said that good risk management plans require accurate assessments of risk factors, particularly as treatment recommendations for asthma evolve.
Also, the researchers recommended expanding population-based disease management strategies to include patients with mild asthma in appropriate preventive therapies to reduce AAEs among these patients.
Perspective
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Andrew M. Namen, MD, FCCP, FAASM
I do believe these results are significant and represent a window into the souls of patients defined with mild asthma who are at risk for AAE.
The design of the study, which was retrospective, has limitations. However, the authors did raise the criteria of what is considered significant as well as stringent criteria of what is defined as mild asthma, including current prescribed medications and how often are they filled.
In regard to the results, although many attributes associated with AAE were not surprising, an understanding of which risk factors and social determinants of health that have a higher risk for an exacerbation is key to assist avoidance of AAE in populations, which has been hard to predict reliably among mild asthmatics.
Surprisingly, use of metformin and insulin was associated with reduced risk for AAE. Is this a result of health care assessments and comprehensive care? Or should patients with mild asthma who are at risk due to a factor such as obesity routinely be screened for glucose intolerance or diabetes? Alternatively, do these medications have a direct impact on asthma exacerbations among mild asthmatics? Further research is needed in these patients.
These results are in line with my experience and help me identify those most at risk and less at risk for AAE. In other words, they help me to discriminate who will likely have more problems with their asthma control.
At this level of evidence, which is retrospective, providers may consider more education and encourage their patients who are most at risk to be mindful of their asthma, use prescribed therapy, ensure proper use — especially those identified at highest risk — and consider screening for glucose intolerance if indicated.
One proposal for the next step in this research would be a large multicenter prospective cohort design study that may implement early interventions (in EDs and urgent care) among those with mild asthma at highest risk (as identified in this study) to include disease or medication educational events, weight loss strategies, enhanced access to treatment and evaluations for eosinophils and hemoglobin A1C.
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