This prospective study was designed to establish the sensitivity and specificity of 2 behavioral pain scales at different gestational ages (GA), during an acute painful procedure. 133 clinically stable neonates, <72h. of life, without CNS diseases, analgesic/sedative use or Apgar <7 at 5′ were randomly assigned to receive capillary puncture (P) or alcohol swab friction (F). Patients were divided in 6 groups, according to GA (Dubowitz: 28-33 wk=group A; 34-37 wk=group B; 38-41 wk=group C) and procedure (P or F): Group A-P (n=17, GA 32±1wk, BW 1.5±0.4kg); A-F (n=18, GA 32±1wk, BW 1.5±0.4kg); Group B-P (n=25, GA 36±1wk, BW 2.5±0.5kg); B-F (n=25, GA 40±1wk, BW 3.3±0.4kg). A neonatologist, blind to P or F, evaluated the Neonatal Facial Action Coding System (NFACS: 0-8 pts, pain > 3) and the Neonatal Infant Pain Scale (NIPS: 0-7 pts, pain>3). All evaluations were performed prior to P or F, without (pr) and with foot heating (h), during (0), 1′ and 3′ after P or F. Reliability was assessed in 20% of the sample by a second observer. Agreement rate was: NFACS-97%, NIPS-95%.
The table (median-variation) shows the following results: A, B, C Groups: NFACS and NIPS P0>F0 (Mann-Whitney, p≤0.0001). A and C Groups: NFACS and NIPS P1>F1 (MW, p≤0.04). C Group: NIPS P3>F3 (MW, p<0.05).
