To determine the effectiveness of parent-led tactile stimulation for pain reduction when added to a combination of evidence-based pain-reducing interventions in infants undergoing immunization injections.
Healthy infants aged 4 to 6 months undergoing routine immunization at a primary care practice were eligible. Infants were randomized to tactile stimulation by a parent or usual care. Parents in the tactile stimulation group rubbed the ipsilateral thigh distal to the site for 15 seconds before, during, and after injections. In addition, all infants received evidence-based pain-relieving interventions including: sucrose solution, holding by a parent, and intramuscular injection without aspiration. The primary outcome was pain, measured by a validated tool, the Modified Behavioral Pain Scale (MBPS), by an observer unaware of treatment allocation using videotapes of the procedure. MBPS scores could range from 0 (no pain) to 10 (maximum pain). Parents, unaware of the study hypothesis, also rated infant pain in real time using a 100 mm visual analogue scale.
One hundred twenty infants participated. Infant characteristics did not differ (P>0.05) between the tactile stimulation and control groups. Mean MBPS scores and parent visual analogue scale scores did not differ between groups (8.2 [1.1] vs. 8.0 [1.3]; P=0.57) and (60  vs. 53  mm; P=0.10), respectively.
Parent-led tactile stimulation did not reduce pain in infants undergoing immunization injections when combined with other pain-relieving interventions. Potential reasons for the lack of effectiveness are discussed. Investigation of the effectiveness of clinician-led tactile stimulation in this population is recommended.