TABLE 1

Study Definitions

Asthma Case Designation
 Asthma: Principal Diagnosis ICD-9 ,493xSecondary Diagnosis ICD-9, None required
 Respiratory failure: Principal Diagnosis ICD-9, 518.81 or 518.82Secondary Diagnosis ICD-9, Asthma: 493x
Asthma severity (based on day 0/1)
 CriticalICD-9 procedure code (93.90, 93.91, 93.93, 96.70, 96.71, 96.72, 96.01, 96.02, 96.03, 96.04, 96.05) or PHIS clinical billing code (521161, 521162, 521164, 521167, 521165, 521169, 521166) for an invasive respiratory therapy or ventilation assistance; order for intravenous terbutaline (PHIS billing code: 181245, route 20)
 SevereOrder for subcutaneous terbutaline (PHIS billing code: 181245, route 23), subcutaneous epinephrine (PHIS billing code: 131321, route 23), or any magnesium sulfate (PHIS billing code: 146147)
 ModerateAll others
Chronic conditions
 Any chronic conditionaDiabetes: 250–250.91; metabolic disorders: 270–273.9, 275-275.9; blood disorders: 281-281.9, 282-9, 283–284.9, 286–286.9, 288–288.9; cerebral palsy: 343.0–343.9; neural degeneration and disease: 330–330.9, 331–331.4, 334–334.2, 340, 341–341.9, 356–356.9; muscular dystrophy: 335-335.9, 359-359.9; epilepsy and seizures: 345–345.91, 780.3; other respiratory: 770.7; congenital and other heart disease: 393–398.9, 414-414.9, 416-416.9, 745–747.49; enteritis and other digestive: 555–555.9, 556-556.9, 579–579.9; chromosomal anomalies: 758.0–758.9; cancer: 140–208.9, 237.7–237.9, 240–246.9; immunocompromised: 279–279.9, 288.1-288.2; HIV 042; autoimmune: 695.4, 710–710.9, 714–714.9, 720.0–720.9; major organ: 070–070.9, 277–277.1, 571–572.8, 581–583.9, 585–587, 588-588.9; mental retardation: 315-315.9, 317–319; congenital anomaly: 740–742.9, 748–751.9, 756–756.9, 758–759.9
Asthma-affecting diagnosis
 Acute upper respiratory infection465×
 PneumoniaaBacterial: 481–482; viral: 480; organism unspecified: 486
 Viral infection079
 Dehydration276.51, E904.2
 Obesity278x
NHLBI diagnoses of importance
 Gastroesophageal reflux530.81
 Obstructive sleep apnea327.23
 SinusitisaChronic: 473x; acute 461x
  • a Each disorder was included in the risk model as individual variables.