Validity and reliability of the N-PASS assessment tool with acute pain

Abstract

Objective: To establish evidence of clinical validity and reliability of the Neonatal Pain, Agitation, and Sedation Scale (N-PASS) in neonates with acute heelstick pain.

Study design: Prospective psychometric evaluation, randomized crossover design. Two nurses administered the N-PASS simultaneously and independently during an actual and sham heelstick done in randomized order. One nurse also administered the Premature Infant Pain Profile (PIPP) concurrently with the N-PASS. Heelsticks were videotaped for repeat analysis.

Result: Construct (discriminate) validity was established through the Wilcoxon Signed-ranks test, comparing the distribution of the heelstick and sham N-PASS scores. The mean pain scores were 3.93 (2.30) and 0.81 (1.21) for the heelstick and sham procedures, respectively (Z=-6.429, P<0.0001). Convergent validity was demonstrated by correlation with the PIPP scores (Spearman rank correlation coefficient of 0.75 and 0.72 for raters 1 and 2, respectively). Inter-rater reliability was high, measured by intra-class coefficients; the ICC estimates (95% CI) of the pain scale were 0.86 (0.78, 0.92) and 0.93 (0.88, 0.96) for a single rating and average of two independent ratings, respectively (P<0.0001). Internal consistency, measured by Cronbach's alpha, was evident (0.84 to 0.89). Test-retest reliability was demonstrated by repeat scoring of videotaped heelsticks, measured by Spearman's rho correlation (0.874, P<0.0001).

Conclusion: This research provides beginning evidence that the N-PASS is a valid and reliable tool for assessing acute heelstick pain in infants 0 to 30 days of age, 23 to 40 weeks gestation.