COPD 10-Fold More Common in Adults with Asthma, Most Severe Comorbidity: Population-Based Study

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Chronic obstructive pulmonary disease (COPD) was found to be the most common and severe comorbidity of adult asthma, nearly 10 times more prevalent in this population than among a matched cohort of adults without asthma, according to a research team from Finland.

Following COPD, the risk each for acute rhinosinusitis, chronic rhinosinusitis with nasal polyps and atopic dermatitis (AD) was 4-fold greater among adults without asthma. Risk of pneumonia was 2.5-fold greater and of allergic rhinitis, 2.3-fold greater. Other common comorbidities of adult asthma included dysfunctional breathing, diabetes, pneumonia, sleep apnea, and gastroesophageal reflux disease.

The findings come from a population-based matched cohort study led by Jussi Karjalainen, MD, PhD, of Tampere University Hospital in Tampere, Finland, and were published online March 14, 2024, in BMJ Open Respiratory Research.

Asthma affects approximately 4% to 10% of the adult population and compared with childhood onset disease is commonly nonatopic and associated with more rapid decline in lung function, the authors wrote. Remission probability is much lower in adult asthma, about 3% to 18% compared with up to 60% in childhood, according to the study. Moreover, asthma-related mortality, health care use, and cost of care also are higher among adults. The researchers state that better understanding and treatment of the many asthma-related comorbidities has the potential to reduce the burden of disease as well as the cost.

The study was designed to explore the range of comorbidities associated with asthma in adults and investigate the differences in distribution of the diseases between Finnish citizens with asthma and controls without asthma matched for age, gender, and area of residence.

Participants with physician-diagnosed asthma were identified from the Drug Reimbursement Register of the Finnish Social Insurance Institution and completed a baseline questionnaire in January 1997. The cohort was followed from January 1998 to December 31, 2013. Extended data for study participants were collected from the national discharge registry of the Institute for Health and Welfare and included information on diagnoses and care in both inpatient and outpatient settings and from primary care and specialists. Follow-up time for the outcomes of interest varied between 14 and 15 years, according to the study.

For their analysis, Karjalainen et al included all main diagnoses that had a minimum of 200 events. They used Cox’s proportional hazards models stratified by the matching criteria. They also adjusted for pack years and/or BMI to evaluate the matched and adjusted hazard ratios (HRs) for asthma among the 2 cohorts.

The final cohort with asthma numbered 1648 and without asthma 3310. The mean age of study participants at enrollment was 53.9 years for those with asthma and 54.4 years for those without asthma; the cohort was 62% women.

FINDINGS

Patients with asthma were less likely to be never smokers, more likely to be ever smokers, and had higher incidences of obesity compared with those without asthma.

COPD was found to be significantly more common among patients with asthma (HR, 7.93; 95% CI, 5.24-12) compared with those without asthma. Additionally, patients with asthma had a 4-fold risk of acute rhinosinusitis, chronic rhinosinusitis with nasal polyps, AD, and vocal cord dysfunction, while pneumonia and chronic rhinosinusitis were 2.5 times more common among patients with asthma. Other comorbidities found to be twice as common among those with asthma were sleep apnea, gastroesophageal reflux disease, diabetes, allergic rhinitis, and dysfunctional breathing. The researchers also reported significant associations between asthma and musculoskeletal diseases, incontinence, and bronchiectasis.

They cite as strengths of the study the long follow-up time, the population-based, matched cohort design, and physician-diagnosed asthma that included lung function tests. Limitations they mention include that data were based on clinical practice and diagnostic coding and may have varied between hospitals or physicians. Second, the use of pharmacotherapy of any kind for asthma could have been a confounding variable and there was no follow-up data available on medication use.

They concluded, however, that “Our study shows that patients with adult asthma suffer from several coexisting diseases that may share similar aetiological and immunological pathways with asthma and decrease” the efficacy of asthma management regimens. They stress the importance of comanagement of comorbidities to enhance care and to reduce cost.

Source: Lemmetyinen RE, Toppila-Salmi SK, But A, et al. Comorbidities associated with adult asthma: a population-based matched cohort study in Finland. BMJ Open Respir Res. 2024;11(1):e001959. Published online March 14, 2024. doi:10.1136/bmjresp-2023-001959