Outcome measures of interest, definition and how they were derived
| Outcome measure | Description | Source | Question | Rationale |
| Care pathways | Colocated maternity unit (place of birth) with neonatal and surgical units, or postnatal transfer via ambulance to surgical centre | Semistructured interviews, focus groups and routine data analysis | Where are infants with CDH delivered and are intensive care and surgical services present at the delivery unit? | Identify care pathways. |
| Received antenatal care | Number of pregnancies that were booked | Routine data on admission | Was the pregnancy booked? | If no antenatal care, likely defect was postnatally diagnosed. |
| Admission <2 hours from birth | Proportion of infants admitted to a neonatal unit within 2 hours from birth. This acts as a proxy measure for antenatal diagnosis. | Routine data on admission | What proportion of infants are admitted to neonatal unit within 2 hours from birth? | Proxy for antenatal diagnosis |
| Median age of admission | Minutes from birth to neonatal unit admission | Routine data on admission | When did the admission occur? | Proxy for antenatal diagnosis |
| Drugs at delivery | Proportion of infants receiving drugs at resus including epinephrine | Routine data on admission | Were resuscitation drugs needed at delivery? | Proxy for disease severity |
| Inotropes on day 1 | Number of infants receiving inotropes on day 1 | Routine data on daily care | Were inotropes used on day 1? | |
| Inhaled nitric oxide on day 1 | Number of infants receiving inhaled nitric oxide on day 1 | Routine data on daily care | Was inhaled nitric oxide used on day 1? | |
| Mechanical ventilation on day 1 | Number of infants on mechanical ventilation on day 1 | Routine data on daily care | Was mechanical ventilation used on day 1? | |
| Transfer patterns | Proportion of postnatal transfers that occurred at 24, 48 and 72 hours from birth | Routine data on discharge | What proportion of infants are transferred out of the first neonatal unit at 24, 48 and 72 hours? | Identify what transfers occur due to the place of birth. |
| Time of transfer to surgical unit | For those infants born in a not colocated centre we report the median age at transfer. | Routine data on discharge | ||
| Ventilation mode during neonatal stay | Ventilation mode received—conventional, high-frequency oscillation or multiple modes. Proxy measure for disease severity. | Routine data on daily care | What ventilation modes are used for CDH management? | Proxy for disease severity |
| Prostaglandin use during neonatal unit stay | Use of prostaglandin during stay in neonatal unit | Routine data on daily care | Was prostaglandin given during neonatal stay? | |
| Inhaled nitric oxide use during neonatal unit stay | Use of inhaled nitric oxide during stay in neonatal unit | Routine data on daily care | Was inhaled nitric oxide given during neonatal stay? | |
| Sildenafil use during neonatal unit stay | Use of sildenafil during stay in neonatal unit | Routine data on daily care | Was sildenafil given during neonatal stay? | |
| Surfactant use during neonatal unit stay | Use of prostaglandin during stay in neonatal unit | Routine data on daily care | Was surfactant given during neonatal stay? | |
| Extracorporeal membrane oxygenation (ECMO) use | Use of ECMO or discharge for ECMO during stay in neonatal unit | Routine data on daily care and discharge details | Did the infant have ECMO or were they discharged from a neonatal unit for ECMO? | |
| Length of neonatal stay | Time from birth to discharge from neonatal unit | Routine data on discharge details | Describe outcomes across care pathways. | |
| Discharge to other settings from neonatal unit | Destination after neonatal episode recorded in NNRD ended: paediatric ward specialist care, for example, cardiac centre, surgical centre or paediatric intensive care. Local repatriation. | Where are infants discharged to? | ||
| Survival to surgical centre | Survived and transferred to surgical centre | |||
| Survival to discharge from neonatal unit | Survived neonatal stay |
CDH, congenital diaphragmatic hernia; NNRD, National Neonatal Research Database.