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Table 1 Algorithm for identification and classification of exacerbations in COPD patients

From: Identifying and characterizing COPD patients in US managed care. A retrospective, cross-sectional analysis of administrative claims data

   1. Inpatient hospitalized exacerbation: an inpatient hospital stay with a primary diagnosis of COPD.

Criteria for exacerbations and exacerbation types (ranked in decreasing severity):

   2. Emergency room visit exacerbation: an emergency room visit with a primary diagnosis of COPD.

   3. Ambulatory exacerbation identified by qualifying diagnosis: an office or outpatient non-emergency room visit with any of the following diagnosis codes in the first position: 136.3, 466-466.19, 480-486, 487.0, 490, 491.21, 491.22, 493.02, 493.12, 493.22, 493.92, 494.1, 506.0-506.3, 507-507.8, 511.0-511.1, 512-512.8, 517.1, 518.0, 518.81, 518.82, 518.84, 770.84.

   4. Ambulatory exacerbation identified by qualifying drug therapy: a pharmacy claim for the following oral antibiotics commonly used for respiratory infections amoxicillin, beta-lactamase inhibitors, second or third-generation cephalosporins, macrolides, or doxycycline) or a claim for systemic steroids (oral, intramuscular, or intravenous).


   1. Only 1 exacerbation is attributed to a patient during any 14-day period (window).

   2. The 14-day period starts with the first claim for an exacerbation of any type.

   3. If the patient meets the criteria for >1 exacerbation during this 14-day window, only a single exacerbation of the most severe type is recorded.

   4. A new 14-day period is begun when a new exacerbation of any type occurs outside of the previous 14-day window.