Table 1.
Operational definitions for asthma and related outcomes from the claims database.
| Operational definition of diagnosis | |
|---|---|
| Asthma-related claim | Claim with ICD-8, 9, and 10 codes (J45.x–J46.x) for the principal or four additional diagnosesa of asthma and at least one asthma-related medicationb. |
| Hospital admission due to asthma exacerbation | Asthma-related claim with systemic corticosteroid prescription for ≥1 days and nebulizer treatmentc. |
| Emergency visit due to asthma exacerbation | Asthma-related claim plus ER code with systemic corticosteroid prescription for ≥1 days and nebulizer treatment. |
| Outpatient clinic visit due to asthma exacerbation | Asthma-related claim with systemic steroid prescription for 2 or more days. |
| Patients with | |
| Asthma | At least 2 asthma-related claims occurred between 6 months before and 6 months after the first claim data of the year. |
| Severe asthmad | Patients who were prescribed with a canister of inhaled corticosteroids (ICSs) equivalent to a canister of high-dose ICSs for >6 months of the year with asthma-related claims. (They must simultaneously satisfy the following criterion: prescribed ICS canisters equivalent to greater than the sum of 12 months prescription of low-dose ICS.) |
| Non-severe asthma | All other patients. |
∗All patients are >5 years of age.
Principal or 4 additional diagnoses: The ICD diagnosis codes that apply to the prescription. In the case of prescriptions for which 5 or more diagnoses are entered, the principal diagnosis code and up to 4 additional diagnosis codes in the following order are applied to the analysis.
Asthma-related medication: inhaled corticosteroids (ICSs), long-acting β-2 agonists (LABAs), ICSs and LABAs combined in a single inhaler (ICSs/LABAs), oral leukotriene antagonists, short-acting β-2 agonists (SABAs), long-acting muscarinic antagonists (LAMAs), short-acting muscarinic antagonists (SAMAs), systemic β agonists, and theophylline derivatives.
Nebulizer treatment: code for nebulizer treatment or nebulizer medications (ICSs, SABAs, and ipratropium bromide).
Severe asthma: we did not apply the definition of severe asthma in the GINA guidelines (2023); asthma that is uncontrolled despite adherence to optimized high-dose ICS-LABA therapy and treatment of contributory factors or that worsens when high-dose treatment is decreased