Patients with asthma and chronic obstructive pulmonary disease (COPD) are at risk for higher mortality, according to results of a longitudinal study published in Respiratory Medicine.
To determine the long-term effect of these disease on total and cause-specific mortality, as well as the comorbidities associated with these diseases, researchers conducted an 18-year follow-up study of patients with asthma, COPD, and asthma-COPD overlap (ACO) who had taken part in Health 2000, a Finnish national health examination survey of adults administered from 2000 to 2001.
At the time that Health 2000 was administered, investigators invited individuals who had asthma, COPD, or ACO and were aged 30 years and older (8028 participants) who completed the survey to take part in a comprehensive clinical examination. The 5922 (73.8%) participants who ultimately completed spirometry, a physician’s evaluation, questionnaires, and serologic determinations were included in the current 18-year follow-up analysis.
For follow-up purposes, investigators assigned an individual identification number to each participant. Health history, including cause of death, was noted from baseline through the end of 2018. In those who died, the cause of death was categorized as being related to cancer, cardiovascular, and respiratory causes. Models were developed to analyze characteristics associated with asthma, COPD, or ACO and to predict mortality according to previous literature.
Of the cohort (3208 women, 2714 men), 320 (5.4%) patients had asthma, 151 (2.5%) had COPD, and 99 (1.7%) had ACO. Mean ages (range) were 56.5 (30-90) years for patients with asthma, 63.9 (35-89) years for those with COPD, and 66.7 (36-90) years for those with ACO.
A total of 1324 (22.4%) deaths occurred in the full cohort during the follow up — 109 (34.1%) with asthma, 90 (59.6%) with COPD, and 64 (64.6%) with ACO. Asthma (hazard ratio [HR] 1.29; 95% CI, 1.05-1.58) and COPD (HR 1.50; 95% CI, 1.20-1.88) were associated with total mortality in the full analysis. Among all deaths, 1221 (92.2%) resulted from natural causes.
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Asthma and COPD increased total mortality during an 18-year follow up, and mortality was comparable with that for cardiovascular disease or diabetes.
Hazard ratios for all-cause natural mortality were 1.26 (95% CI, 1.02-1.56) for asthma, 1.54 (95% CI, 1.23-1.93) for COPD, and 1.30 (95% CI, 1.00-1.69) for ACO. Hazard ratios for total mortality were 1.61 (95% CI, 0.87-2.98) for asthma, 2.09 (95% CI, 1.12-3.89) for COPD, and 0.57 (95% CI, 0.23-1.42) for ACO after exclusion of the 10 first years postsurvey.
Cardiovascular death was associated with asthma (HR 1.47; 95% CI, 1.09-1.97) and COPD (HR 1.53; 95% CI, 1.08-2.16). Respiratory deaths were associated with asthma (HR 2.62; 95% CI, 1.13-6.07), COPD (HR 2.32; 95% CI, 1.00-5.36), and ACO (HR 3.55; 95% CI, 1.73-7.27). With respect to cancer deaths, unadjusted HRs were highest for patients with COPD (HR, 4.85; 95% CI, 3.29-7.16) and ACO(HR, 4.42; 95% CI, 2.67–7.32), and lower for those with asthma (HR, 1.25; 95% CI, 0.79-2.00).
The mortality risk was increased in patients with ACO and high sensitivity C-reactive protein of 1 to 2.99 mg/L (HR 2.32; 95% CI, 1.53-3.52), although ACO did not predict mortality in the full cohort.
With respect to limitations, the researchers noted that their study involved a general health examination survey, and only a limited number of participants had asthma, COPD, or ACO. In addition, data on inhaled medications and smoking pack-years were not available at baseline; there was overlap in disease categorization; and some changes may have occurred in medical treatment for various diseases and in categorizing and documenting causes of death during follow-up.
Based on their findings, investigators concluded that asthma and COPD predicted cardiovascular mortality; asthma, COPD, and ACO predicted respiratory mortality; and COPD predicted cancer mortality. Overall, “Asthma and COPD increased total mortality during an 18-year follow up, and mortality was comparable with that for cardiovascular disease or diabetes,” stated the investigators. They further noted that “Total mortality was not significantly increased in those with ACO, probably due to the small number of subjects.”
