Assessment of bias using Newcastle-Ottawa Scale
| Author | Selection | Comparability | Outcome | Total Score | ||||||
| Representativeness of cohort | Selection of non-exposed cohort | Ascertainment of exposure | Outcome of interest | Controls for birth weight or gestational age | Controls for NICU centre, central line days | Assessment | Follow-up duration >6 months | Completeness of follow-up | ||
| Arnts | * | * | * | * | * | – | * | * | - | 7 |
| McMullan | * | – | * | * | – | – | * | * | * | 6 |
| Salm | * | – | * | * | * | * | * | * | * | 8 |
| Schulman | * | – | * | * | * | * | * | * | * | 8 |
| Wang | * | * | – | * | * | – | * | * | - | 6 |