Validation of the Numerical Anxiety Rating Scale in postpartum females: a prospective observational study

Objectives: Perinatal anxiety is important for the quality of life of mothers and their offspring. The Numerical Anxiety Rating Scale (NRS-A) allows the level of anxiety in patients to be quickly assessed. Until now, the NRS-A has not been validated in the postpartum female population. The aim of this study was to assess the accuracy and reliability of the NRS-A when compared with the reference methods for measuring anxiety. Material and methods: The observational prospective study included a group of 200 adult postpartum females of a hospital maternity ward. The validity between the Numerical Rating Scale for Anxiety (NRS-A) and the State and Trait Anxiety Inventory (STAI), and between the NRS-A and the Hospital Anxiety and Depression Scale (HADS-A), was determined. The detection thresholds for high anxiety were examined. Results: Both measurements showed a positive high correlation between the NRS and STAI-S (in T1 rho = 0.807, in T2 rho = 0.778; p < 0.001), and a comparable relationship of both scales (STAI-S and NRS-A) with the STAI-T and HADS-A. The analysis of the ROC curve indicated that the value of the NRS-A equal to 3.5/10 can be considered the threshold that allows for a differentiation of patients with high anxiety from those without high anxiety in the studied population. Conclusions: The NRS-A is an accurate tool for measuring anxiety in Polish postpartum females. Routine anxiety measurements using the NRS-A can be used to identify people with high anxiety in order to provide emotional support to patients in the early postpartum period.