Validity and use of the Neonatal Infant Stressor Scale: An integrative review

Stress exposure, operationalized as a count of painful or skin-breaking breaking procedures, is an important concept for inclusion in studies of preterm infants. The Neonatal Infant Stressor Scale (NISS) was developed to also account for nonpainful and environmental stressors; however, validity of this measure is unknown.

The purpose of this review was to define the breadth of use of the NISS in neonatal research studies and determine its predictive and concurrent validity.

Using the methods for integrative review, a systematic search of the literature was conducted using PubMed, CINAHL, PsycINFO, and Embase with keywords "NISS" OR "Neonatal Infant Stressor Scale". Study findings were narratively synthesized.

Twenty-nine articles were retained for the review and included two cross-sectional studies describing development or adaptation of the measure, two protocols for empirical studies, and 25 empirical studies of preterm infants. Modifications to the original NISS were common and included addition or exclusion of specific stressors and use of unweighted scores. Although findings were inconsistent across studies, limited data support the predictive validity of the NISS, as higher NISS scores have been associated with abnormal brain development and cognitive, motor, and behavioral deficits. Two studies found concurrent associations between NISS scores and cortisol.

The NISS may be a useful tool to quantify stressors experienced by preterm infants; however, there are only limited data to support its predictive or concurrent validity. The NISS may be particularly useful as a method to bring awareness to the infant's stress burden in clinical practice. Additional research is needed to validate inclusion of specific stressors in the NISS.