Usefulness of Percent Change in NIPE and Correlation With PIPP-R to Assess Neonatal Pain Following Blood Collection

Purpose: To evaluate the usefulness of the newborn infant parasympathetic evaluation (NIPE) percentage change instead of the NIPE absolute values. Additionally, we investigated the correlation between 2 neonatal pain assessment tools, the premature infant pain profiled—revised (PIPP-R) scale and NIPE, after blood extraction. Background: Pain assessment is crucial for optimizing pain prevention and providing appropriate treatment; therefore, research on the best way to use pain assessment tools is required. Methods: A prospective observational study was performed with infants admitted to the neonatal intensive care unit between June 2022 and April 2023 who underwent blood collection. Demographic data, aspects related to the procedure, PIPP-R, and NIPE index at baseline and 8 minutes following the procedure were recorded. Results: The sample included 134 recordings, corresponding to 70 patients. The correlation coefficient for the association between PIPP-R scores and NIPE variations was weak: 0.32 (P < .05). To identify severe pain taking as reference PIPP-R ≥12 area under the curve (AUC) for percentage decrease of NIPE, NIPE values at first and second minutes were 0.68 (95% confidence interval: 0.59-0.78; P < .01); 0.5 (0.45-0.64; P = .4); 0.59 (0.50-0.68; P = .2) respectively. The best cutoff value for the percentage decrease in NIPE was 13%. Conclusion: The correlation between NIPE and PIPP-R scores was weak. The percentage decrease in the NIPE had better sensitivity, specificity, and AUC than the absolute values of the NIPE. Implications for practice and research: maximum percentage decrease in NIPE detects severe pain better than the absolute NIPE value. As the correlation was weak, neonatal pain assessment should include all available tools.