Table 2 Comparison of NICUS variable codes and ICD9 codes available in the Admitted Patient Data Collection, New South Wales, Australia, 1994–1996

Intraventricular hemorrhage (IVH) and other brain hemorrhages

IVH was coded as YES (grades 1–4) or NO (none/not examined)

A single head ultrasound (HUS) abnormality can be recorded and coded:

0:None; 1:Cerebral oedema; 2:Subarachnoid hemorrhage; 3:Periventricular echogenicity; 4:Cerebellar hemorrhage; 5:Subdural hemorrhage; 6:Extradural hemorrhage; 7:Other; 8 Not examined.

772.1 Neonatal IVH

772.2 Neonatal subarachnoid hemorrhage

767.0 Subdural and cerebral hemorrhages

772.1, 772.2 or 767.0 any brain hemorrhage

Any brain hemorrhage was coded YES where IVH = YES or HUS in (2,4,5,6) and NO where HUS abnormality of 'none' or 'not examined'.

Respiratory diagnoses

A single 'primary respiratory diagnosis' can be recorded and coded:

0:None; 1:Transient tachypnea of the newborn (TTN); 2:Respiratory distress syndrome (RDS); 3:Meconium aspiration; 4:Immature lung; 5:Apnea; 6:Congenital anomaly; 7: Pulmonary hypertension; 8:Pneumonia; 9:Perinatal surgery; 10:Other; or 11:Unknown

769 Respiratory distress syndrome (neonatal)

770.6 Transient tachypnea of the newborn

770.1 Meconium aspiration syndrome

770.0 Congenital pneumonia

480–486 Pneumonia

416.0 Pulmonary hypertension

A single 'main indication for initial ventilation" can also be recorded and coded 1–7 as above or; 8:Infection (any site); 9:Asphyxia; 10: Cardiac disorder; 11:Post-surgery; 12:Other

Any diagnosis of transient tachypnea, respiratory distress syndrome, meconium aspiration, pulmonary hypertension or pneumonia was coded YES and 'primary respiratory diagnosis of 'none' coded NO

Retinopathy of prematurity (ROP)

ROP was coded as YES (grades 1–4 or treatment for ROP) or NO (none/not examined)

362.21 Retrolental fibroplasia

362.10 Retinopathy unspecified

14.2 Destruction of chorioretinal lesion

36.21, 362.10 or 14.2 coded as ROP

Necrotizing enterocolitis (NEC)

NEC coded as YES (clinically diagnosed or proven radiologically/at surgery) or NO (None)

777.5 Necrotizing enterocolitis in newborn

Selected major anomalies

Recorded using ICD9 diagnosis codes for any of the following:

anomalies of diaphragm, anomalies of abdominal wall, spina bifida, tracheo-oesophageal fistula (TOF), oesophageal atresia and stenosis and tetralogy of fallot (see next column for ICD codes)

756.6 Diaphragm anomalies

756.7 Abdominal wall anomalies

741 Spina bifida

750.3 TOF, oesophageal atresia and stenosis

745.2 Tetralogy of fallot

Procedures

Continuous positive airway pressure (CPAP)

Recorded using 4 variables indicating number of days of endotracheal tube CPAP, nasopharyngeal CPAP, continuous nasal CPAP and intermittent nasal CPAP: 1 or more days of any of these recorded as YES, 0 days recorded as NO

93.90 Continuous positive airway pressure (CPAP)

Mechanical ventilation (including CPAP)

Mechanical ventilation or CPAP, YES or otherwise NO

93.90 Continuous positive airway pressure (CPAP)

93.91 Intermittent positive airway pressure breathing

96.7 Continuous mechanical ventilation

93.90, 93.91, or 96.7 for any mechanical ventilation

Drainage of air leak

Recorded as air leak requiring drainage YES or NO

34.04 Insertion of intercostal catheter for drainage

Surgery for patent ductus arteriosus (PDA)

PDA surgery coded as YES or NO

38.85 Ligation of PDA

Surgery for necrotizing enterocolitis (NEC)

NEC surgery coded as YES or NO

777.5 Necrotizing enterocolitis in newborn

45.6–46.5 Operations on the small or large intestine

43.19 Other gastrostomy

54.11, 54.19 Laparotomy

54.59 Lysis of peritoneal adhesions

77.5 and 45.6–46.5, 43.19, 54.11, 54.19, or 54.59 for NEC surgery