DG Journal Club
OBJECTIVES Infants born preterm are exposed to repeated painful procedures during neonatal intensive care unit admission. Particularly in preterm infants, trajectories of pain response are not well understood. The aim of this study was to classify pain response trajectories over two-minutes following medically indicated heel lances in preterm infants.
METHODS This study used existing clinical trial data (NCT01561547) which evaluated the efficacy of kangaroo care and sucrose for infant pain control. Pain was measured using the Premature Infant Pain Profile at 30, 60, 90, and 120 seconds following a heel lance. Group based trajectory modeling was used to classify pain response in this two-minute period.
RESULTS A total of 236 infants with median gestational age of 33 weeks contributed 610 procedures. A model with five trajectory classes best fit the data. Three trajectories were stable over time at different levels of intensity from low-mild to low-moderate pain. One trajectory reflected a linear reduction from high- to low-moderate pain. The final trajectory showed variable moderate-high pain. At all times points, three classes were at least one-point different from the overall sample mean pain score. Only 21 (9%) infants maintained the same class for all three procedures.
DISCUSSION In this sample of preterm infants receiving pain relief, most pain trajectories reflected mild to low-moderate pain that was stable over two-minutes after heel lance initiation. Trajectories were not consistent over multiple procedures within infants, and an overall mean pain score for the sample may misrepresent subgroups of pain response.