Quantification of stress exposure in very preterm infants: Development of the NeO-stress score

Background: Stress during treatment at the Neonatal Intensive Care Unit (NICU) has long-term negative consequences on preterm infants' development. Aims: We developed an instrument suited to validly determine the cumulative stress exposure for preterm infants in a NICU. Study design: This survey study made use of two consecutive questionnaires. Subjects: NICU nurses and physicians from the nine NICUs in the Netherlands. Outcome measures: First, respondents rated the relevance of 77 items encompassing potentially stressful procedures, commented on their comprehensibility and the comprehensiveness of the list. We calculated the content validity per item (CVI-I) and included only the relevant items in a second questionnaire in which the participants rated the stressfulness from 0 (not stressful) to 10 (extremely stressful). A stressfulness index – representing the median score – was calculated for each included item. Results: Based on the CVI-I of the 77 items, step 1 resulted in 38 items considered relevant to quantify stress in preterm infants during the first 28 days of life. This list of 38 items exists of 34 items with a CVI-I if 0.78 or higher, one of these items was split into two items, and three items were added to improve comprehensiveness. The stressfulness index ranged from five to nine. Conclusions: The NeO-stress score consists of stressful items including their severity index and was developed to determine cumulative stress exposure of preterm infants. Evaluating the cross-cultural validity, correlating it to behavioural and biological stress responses, and evaluating its ability to predict preterm infants at risk for the negative effects following stress might expand the possibilities for this instrument.