Table 1.
—ICD-9-CM Codes Used in Algorithms to Identify AE-COPD
| ICD-9-CM Code | Description |
| 490 | Bronchitis, not specified as acute or chronic |
| 491.0 | Simple chronic bronchitis |
| 491.1 | Mucopurulent chronic bronchitis |
| 491.20 | Obstructive chronic bronchitis without exacerbation |
| 491.21 | Obstructive chronic bronchitis with acute exacerbation |
| 491.22 | Obstructive chronic bronchitis with acute bronchitis |
| 491.8 | Other chronic bronchitis |
| 491.9 | Unspecified chronic bronchitis |
| 492.0 | Emphysematous bleb |
| 492.8 | Other emphysema |
| 493.22 | Chronic obstructive asthma with acute exacerbation |
| 496 | Chronic airway obstruction, not elsewhere classified |
| 518.81 | Acute respiratory failure |
| 518.82 | Other pulmonary insufficiency not elsewhere classified |
| 518.84 | Acute and chronic respiratory failure |
| 799.1 | Respiratory arrest |
All ICD-9-CM codes used to identify patients hospitalized for AE-COPD in the four coding algorithms examined are included. AE-COPD = acute exacerbation of COPD; ICD-9-CM = International Classification of Disease, Ninth Edition, Clinical Modification.