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Predicting 15 year chronic bronchitis mortality in the Whitehall Study
1Department of Epidemiology, London School of Hygiene and Tropical Medicine.
Journal of Epidemiology and Community Health
|June 1, 1989
Summary
Low FEV1, a measure of lung function, strongly predicts chronic bronchitis mortality. Chronic phlegm alone does not predict mortality, but its combination with airflow limitation does.
Area of Science:
- Respiratory Medicine
- Epidemiology
- Public Health
Background:
- Chronic bronchitis poses a significant public health challenge, contributing to substantial mortality.
- Understanding predictors of chronic bronchitis mortality is crucial for targeted interventions.
Purpose of the Study:
- To investigate the association between respiratory symptoms, lung function, and chronic bronchitis mortality.
- To identify the most potent predictors of mortality in a cohort of male civil servants.
Main Methods:
- A 15-year mortality follow-up of 17,717 male civil servants aged 40-64 years (Whitehall Study).
- Assessment of mortality risk associated with Medical Research Council (MRC) standardized questionnaires on chronic phlegm and breathlessness.
- Evaluation of lung function, specifically FEV1 (Forced Expiratory Volume in 1 second), as a predictor.
Main Results:
- Low FEV1 was the strongest predictor of mortality (Relative Hazards Ratio [RHR] = 20), accounting for 57% of population attributable mortality.
- Breathlessness on level walking was the best symptom predictor (RHR = 12), accounting for 39% of population attributable mortality.
- The MRC definition of chronic bronchitis (phlegm + breathlessness) showed a lower population impact (RHR = 13, 20% attributable mortality) and identified only 30% of deaths.
Conclusions:
- Chronic airflow limitation (low FEV1) is a primary driver of chronic bronchitis mortality.
- While breathlessness is a significant predictor, chronic phlegm production alone is not associated with increased mortality.
- Effective prediction and intervention for chronic bronchitis mortality should prioritize lung function measures and breathlessness over phlegm production alone.