COPD hospitalization risk declines with better cardiovascular autonomic function
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Key takeaways:
- Patients with elevated heart rate variability faced a decreased risk for COPD hospitalization.
- In contrast, an increased risk was observed among those with orthostatic hypotension.
Having high heart rate variability and low orthostatic hypotension reduced the risk for incident COPD hospitalization, according to study results published in Annals of the American Thoracic Society.
“Hopefully these findings can lead to new ways to identify those at risk of worse COPD outcomes in the future, but this will require further study,” David M. MacDonald, MD, MS, assistant professor of medicine at the University of Minnesota and staff physician in the pulmonary section at the Minneapolis VA Health Care System, told Healio.
Using the cohort from the Atherosclerosis Risk In Communities study, MacDonald and colleagues assessed 11,625 patients (mean age, 53.8 years; 56.5% women; 26.3% Black) to find out how heart rate variability (HRV) and orthostatic hypotension — measures of the cardiovascular autonomic nervous system — are each linked to incident COPD hospitalization.
Researchers collected data from 2-minute electrocardiograms and used orthostatic hypotension variables to determine their relation to incident COPD hospitalization through Cox proportional hazards regression models adjusted for demographic data, smoking status, lung function, comorbidities and physical activity.
Notably, airflow obstruction was found in 22.4% of patients at baseline, and this set of patients had poorer measures of lung function compared with patients without airflow obstruction (mean FEV1 percentage predicted, 78.4% vs. 98.7%; FEV1/FVC ratio, 0.63 vs. 0.78).
Researchers observed 2,406 incident COPD hospitalizations over the 26.9-year median follow-up period, and a greater proportion of patients with vs. without airflow obstruction experienced this outcome (43.5% vs. 14.1%).
In the adjusted model, the risk for COPD hospitalization was reduced among patients with higher HRV, which signals better autonomic function. Researchers noted that several measures made up HRV (R-R interval, low-frequency power and low-frequency/high-frequency ratio), so when these were increased, the risk for COPD hospitalization went down.
In contrast, the risk for incident COPD hospitalization rose when patients possessed worse autonomic function, as seen through orthostatic hypotension (HR = 1.51; 95% CI, 1.25-1.82) and greater changes in systolic (HR = 1.08; 95% CI, 1.03-1.13) and diastolic (HR = 1.03; 95% CI, 0.99-1.08) blood pressure.
Between those with vs. without airflow obstruction, researchers typically found stronger links between measures of autonomic function and incident COPD hospitalization among those without airflow obstruction.
“The most surprising finding was that autonomic dysfunction predicted COPD hospitalizations in people without baseline airflow obstruction,” MacDonald told Healio. “Associations between autonomic dysfunction and COPD have been established for a long time, but this novel finding suggests that autonomic dysfunction could contribute to COPD development or be a tool to identify those at risk of worse outcomes from COPD in the future.”
In an additional analysis, researchers evaluated how the relationships observed above differed by sex, smoking status and lung function.
Although the link between HRV and COPD hospitalization risk did not differ based on sex, researchers did find that women with orthostatic hypotension and large reductions in systolic and diastolic blood pressure had a heightened risk for COPD hospitalization, whereas men did not face an increased risk.
When divided based on smoking status, the link between HRV and COPD hospitalization from the main analysis, as well as between orthostatic hypotension and COPD hospitalization also appeared in never smokers.
Researchers did not find “consistent trends” between the two main measures of cardiovascular autonomic function and COPD hospitalization when looking at interactions by lung function.
“Future studies will use longer heart rate variability recordings and test additional outcomes, such as lung function and clinically diagnosed respiratory disease,” MacDonald told Healio. “These findings may also have applicability with the increasing use of wearables, such as smartwatches and other devices with the ability to measure heart rate.”