What is the clinical evidence from this study?

Study design: Cohort. Population: Referred for incremental cycle exercise testing (n=13506). Intervention: Abnormally high exertional breathlessness vs. Normal exertional breathlessness. Primary outcome: All-cause mortality (aHR 2.3, 95% CI 2.1-2.6, p=<0.001).

December 18, 2024PLoS ONE11 citationsOpen Access

Abnormally high exertional breathlessness predicts mortality in people referred for incremental cycle exercise testing

Q: What are the key findings of this study?

Abnormally high exertional breathlessness during incremental cycle exercise testing was associated with a significantly higher risk of all-cause mortality (aHR 2.3) compared to normal breathlessness.

VEViktor Elmberg XZXingwu Zhou TLThomas Lindow

Key Result

Abnormally high exertional breathlessness during incremental cycle exercise testing was associated with a significantly higher risk of all-cause mortality (aHR 2.3) compared to normal breathlessness.

Study Design

Type

Cohort (n=13,506)

Multicenter

Structured PICO

Does abnormally high exertional breathlessness during incremental cycle exercise testing predict mortality in adults referred for clinical exercise testing?

Population

13,506 adults (mean age 59 years, 46% female) referred for incremental cycle exercise testing were followed for a median of 8.0 years to assess mortality.

Exposure

Abnormally high exertional breathlessness during incremental cycle exercise testing (defined as a Borg CR10 breathlessness intensity rating > the upper limit of normal using published reference equations).

Comparator

Normal exertional breathlessness intensity (Borg CR10 rating ≤ the upper limit of normal).

Outcome

All-cause, respiratory, and cardiac mortality assessed using the Swedish National Causes of Death Registry.hard clinical

Abnormally high exertional breathlessness during routine clinical exercise testing is a strong, independent predictor of all-cause, respiratory, and cardiac mortality.

Main Result

Hazard Ratio: 2.3 (95% CI 2.1–2.6)

p-value: p=<0.001

Limitations

Physiological data were limited, with no access to pulmonary function tests, ventilation, or gas exchange to ensure maximal effort.
Findings pertain to cycle ergometer exercise and may not be directly applicable to treadmill (weight-bearing) exercise.
Possible bias from more frequent breathlessness inquiries in highly symptomatic patients.
Sensitivity for milder diseases like hypertension is lower in the National Patient Register.
No information on the specific reasons behind abnormally high exertional breathlessness or smoking status.
Single-center study design.

Abstract

BACKGROUND: Exertional breathlessness is a key symptom in cardiorespiratory disease and can be quantified using incremental exercise testing, but its prognostic significance is unknown. We evaluated the ability of abnormally high breathlessness intensity during incremental cycle exercise testing to predict all-cause, respiratory, and cardiac mortality. STUDY DESIGN AND METHODS: Longitudinal cohort study of adults referred for exercise testing followed prospectively for mortality assessed using the Swedish National Causes of Death Registry. Abnormally high exertional breathlessness was defined as a breathlessness intensity response (Borg 0-10 scale) > the upper limit of normal using published reference equations. Mortality was analyzed using multivariable Cox regression, unadjusted and adjusted for age, sex, and body mass index. A further mortality analysis was also done adjusted for select common comorbidities in addition to age, sex and body mass index. RESULTS: Of the 13,506 people included (46% female, age 59±15 years), 2,867 (21%) had abnormally high breathlessness during exercise testing. Over a median follow up of 8.0 years, 1,687 (12%) people died. No participant was lost to follow-up. Compared to those within normal predicted ranges, people with abnormally high exertional breathlessness had higher mortality from all causes (adjusted hazard ratio aHR 2.3, 95% confidence interval 2.1-2.6), respiratory causes (aHR 5.2 3.4-8.0) and cardiac causes (aHR 3.0 2.5-3.6). Even among people with normal exercise capacity (defined as peak Watt ≥75% of predicted exercise capacity, n = 10,284) those with abnormally high exertional breathlessness were at greater risk of all-cause mortality than people with exertional breathlessness within the normal predicted range (aHR 1.5 1.2-1.8). CONCLUSION: Among people referred for exercise testing, abnormally high exertional breathlessness, quantified using healthy reference values, independently predicted all-cause, respiratory and cardiac mortality.

Ask AI

Helpful

Bookmark

View Full Paper