New Study Identifies Key Risk Factors Likely to Accelerate a COPD Diagnosis in Patients with Asthma

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A large 18-year Canadian cohort study published in the journal COPD highlights several key risk factors that are likely to accelerate the progression from asthma to chronic obstructive pulmonary disease (COPD).

Aiming to determine risk factors that accelerate time-to-COPD diagnosis—which have yet to be clearly identified—researchers from Memorial University of Newfoundland used 4 health administrative claim databases obtained from Canada’s Population Data BC (PopData BC) to identify patients with asthma without a prior COPD diagnosis between January 1, 1998, and December 31, 1999.

Patients were assessed for time-to-incidence of COPD diagnosis from January 1, 2000, to December 31, 2018. The primary outcome measure was time to the first diagnosis of COPD during the 18-year follow-up period.

Estimates of risk factors for predicting the incidence of COPD in patients with asthma during the study follow-up included several sociodemographic factors, such as a year of the index (January 1, 1998, to December 31, 1999), sex, age, obesity (body mass index >30 kg/m2), and lifestyle variables (ie, tobacco use/nicotine dependence).

Researchers also evaluated asthma medication adherence (MA), which was assessed by 2 proxy variables on a scale of 0 to 1, defined as the proportion of days covered (PDC) and the medication possession ratio. Another risk factor considered in the study was the Charlson comorbidity index (CCI), which measured the burden of comorbid conditions among participants with asthma after excluding asthma from the score.

A total of 68 211 (40.09% men; mean age, 48.2 years) patients with physician-diagnosed asthma at baseline were included in the analysis. After 1 036 811 years of person-time follow-up, 15% (n=10 170) of participants were diagnosed with COPD, according to the study results.

Based on disease severity, the incidence of COPD diagnosed among participants with mild asthma was 0.85 per 1000 person-years (n = 886), 2.82 per 1000 person-years (n=2924) among those with moderate asthma, and 6.13 per 1000 person-years among those with severe asthma (n=6360).

With regards to the burden of comorbidities associated with asthma at baseline, 97.8% of the patients had no comorbid condition (CCI score, 0), while 1.8% had a CCI score of 1 and 0.32% had a CCI score of ≥2. Also, sinusitis and upper respiratory infections were identified in 0.16% and 0.42% of participants at baseline.

The following risk factors were found to accelerate time-to-COPD diagnosis:

• Male sex (adjusted failure time ratio [aFTR], 0.62; 95% confidence interval [CI], 0.56-0.68; P<.0001).
• Older adults (ie, aged >40 years; aFTR, 0.03; 95% CI, 0.02-0.04; P<.0001).
• History of tobacco smoking (aFTR, 0.29; 95% CI, 0.13-0.6; P=.004).
• Asthma exacerbation (aFTR, 0.81; 95% CI, 0.70-0.94; P=.007).
• Frequent emergency department admissions (aFTR, 0.21; 95% CI, 017-0.25; P=.000).
• Longer hospital stays (aFTR, 0.07; 95% CI, 0.06-0.09; P<.0001).
• Increased burden of comorbidities (aFTR, 0.28; 95% CI, 0.22-0.34; P<.0001).
• Male sex with obesity (aFTR, 0.38; 95% CI, 0.15-0.99; P=.049).
• Short-acting beta-2 agonist overuse (aFTR, 0.61; 95% CI, 0.44-0.84; P=.003).
• Moderate asthma (aFTR, 0.23; 95% CI, 0.21-0.26; P=.000).
• Severe asthma (aFTR, 0.10; 95% CI, 0.08-0.12; P=.000).

In addition, after adjustment, optimal MA (ie, PDC ≥0.80) was associated with an 83% significantly delayed time-to-COPD diagnosis (aFTR, 1.83, 95% CI: 1.54-2.17 for PDC; P<.0001). Asthma severity, however, was shown to significantly modify the effect of MA, independent of tobacco smoking history.

“Healthcare providers and policymakers should emphasize greater medication adherence as preventive and intervention measures capable of reducing the risk of COPD in asthma patients,” concluded study authors. “Patient-specific education and counseling should be intensified to increase their awareness of the importance of adhering to prescribed medications over time, minimizing unhealthy lifestyles such as cigarette smoking and sedentary lifestyles leading to obesity, particularly in male patients.”

Reference: Asamoah-Boaheng M, Farrell J, Osei Bonsu K, Midodzi WK. Examining risk factors accelerating time-to-chronic obstructive pulmonary disease (COPD) diagnosis among asthma patients. COPD. Published online January 10, 2022. doi: 10.1080/15412555.2021.2024159.