Table 1. Major etiologies identified in studies on chronic unexplained dyspnea. Cardiopulmonary diseases comprise two-thirds of the underlying causes.
| Etiology | Prevalence, % |
|---|---|
| Respiratory | |
| “Unspecified” airway disease | 25-37 |
| Asthma | 16-29 |
| Airway hyperresponsiveness | 25 |
| Pulmonary vascular disease | 5- 17 |
| COPD | 9-14 |
| Interstitial lung disease | 7-14 |
| Other | 2-9 |
| Cardiocirculatory | |
| Chronic (systolic or diastolic) heart failure | 6-17 |
| Ischemic heart disease | 5 |
| Other | 8 |
| Noncardiopulmonary diseases (less common) | |
| Obesity | 16 |
| Dysfunctional breathing | 5-32 |
| Deconditioning | 3-28 |
| Myopathies | 1-24 |
| Dysautonomia | 21 |
| Miscellaneous | 2-7 |