Variables
Demographic data was collected and included: date of birth, age at time of PSG, age at time of echocardiogram, gender, race, BMI z-score (age >2 years) / weight for height z-score (age <2 years) at time of echocardiogram, and blood pressure and oxygen saturations closest to echocardiogram date. Data on medical comorbidities was collected based on diagnostic billing codes (ICD-10). Comorbidities studied were prematurity, bronchopulmonary dysplasia, laryngomalacia, craniofacial anomaly, trisomy 21, neuromuscular disorder or Arnold Chiari malformation, hypertension, pulmonary hypertension, feeding dysfunction, and obesity. Surgical history was collected on adenoidectomy, tonsillectomy or adenotonsillectomy as well as cardiac surgery and type. Heart defects in all children were noted and broadly classified into two groups: structural heart disease or no structural heart disease.