Influence of gestational age on the EDIN score: an observational study

Background and aim: Hospitalised neonates, particularly if preterm, may be exposed to prolonged pain. At present the only validated scale to assess prolonged pain in preterms is the EDIN (Echelle Douleur Inconfort Nouveau-Ne) scale. Gestational age has been shown to influence the response of infants to acute pain but its potential effect in the setting of prolonged pain has not been investigated. The aim of the present study was to evaluate whether neonatal maturity as expressed by gestational age and/or postnatal age influences their expression of prolonged pain. Methods: In a 1 year period, 84 neonates (gestational age 25-41 weeks), referred to the authors' neonatal intensive care unit were evaluated using the EDIN scale two to three times a day (1571 scores). The EDIN scores were categorised as indicative (>6) or not indicative ( <= 6) of pain. Gestational age and postnatal age were included in a logistic regression analysis along with some painful situations and analgesic treatment to identify the impact on the EDIN scores. Results: Logistic regression analysis showed that the EDIN scores were positively associated with gestational age (odds ratio 1.166; 95% CI 1.123 to 1.211). Postnatal age, sepsis and presence of respiratory support also influenced the EDIN score. Conclusions: Gestational age influences expression of prolonged pain. Content validity of the EDIN scale could be improved by adding categories for gestational age and attributing higher basal scores to less mature newborns.