Table 1.
Pre-specified study outcome definitions.
| Outcome | Code(s) | Risk Period(s) | Medical Record Confirmation Criteria |
|---|---|---|---|
| Intussusception* | ICD-9 diagnosis code 543.9, 560.0 or CPT code 74283 | 0–59 | Level 1 definite criteria per the Brighton Collaboration (radiographic or surgical confirmation, or evidence at autopsy) |
| 0–6 | |||
| 0–29 | |||
| Hospitalization due to acute LRTI† | ICD-9 diagnosis code 466, 480–486, 487.0, 490, 513.0; | 0–59 | N/A |
| AND | 0–6 | ||
| At least one procedure code for radiologic examination of the chest within +/- 3 days of the diagnosis: CPT 71010, 71015, 71020 – 71023, 71030, 71034, 71035; ICD-9 procedure 87.44, 87.49 | 0–29 | ||
| Kawasaki Disease* | ICD-9 diagnosis code 446.1 | 0–59 | US CDC surveillance case definition: Fever ≥5 days duration (or until administration of IV immunoglobulin), AND presence of at least 4 of the following clinical signs: rash, cervical lymphadenopathy(at least 1.5 cm in diameter), bilateral conjunctival injection, oral mucosal changes, peripheral extremity changes |
| Convulsion* | ICD-9 diagnosis code 333.2, 345, 779.0, 780.3 | 0–59 | Brighton Collaboration Seizure Working Group definition: Generalized or focal tonic, clonic, tonic-clonic, or atonic motor manifestations, AND witnessed sudden alteration of consciousness (Level 1 of diagnostic certainty) OR history of altered consciousness (Level 2 of diagnostic certainty) |
| All-Cause Mortality‡ | ICD-9 diagnosis code 798, 798.0, 798.1, 798.2, 798.9; UB-92 form patient discharge status code 20, 40, 41, 42 | 0–59 | N/A |
| Additional deaths identified through the NDI data |
Abbreviations: CDC = Centers for Disease Control and Prevention; CPT = current procedural terminology code; ED = emergency department; ICD-9 = International Classification of Diseases, 9th Revision; LRTI = lower respiratory tract infection; N/A = not applicable; NDI = National Death Index; UB = Uniform/Universal billing; US = United States.
*
Codes were associated with a hospitalization or ED encounter.
†
Codes were associated with a hospitalization.
‡
Codes were associated with a hospitalization, ED, or outpatient encounter.