Temperament as a Predictor of Infant Immunization Distress and Response to Treatment

There is a growing body of research on interventions to decrease infant distress during painful procedures, and distraction is a particularly practical option. However, the effectiveness data for distraction for infant pain relief are mixed. Inconsistencies in response to distraction might be explained by unique characteristics of the infant patient. Some researchers argue that temperament is the best predictor of differences observed between individuals and also the most sensitive to novel environmental factors such as exposure to pain. This study examined whether infants‟ temperament is predictive of response to immunization injection pain and whether temperament moderates the relation between a distraction intervention and infant distress. Data for this study came from two prior studies of healthy infants receiving immunizations (Cohen, 2002; Cohen et al., 2006). Participants included 252 healthy infants and toddlers who ranged from 1 to 22 months of age. Infants were randomly assigned to “typical care” condition or “distraction” condition. The period of time before, during, and after the injection was videotaped and observational coding was used to assess infant distress. Prior to the immunization, parents completed six pre-injection visual analogue scales about their child‟s temperament. An oblique rotation factor analysis was conducted with the temperament data and provided two temperament factors that map onto the „easy/difficult‟ and „time-to-warm-up‟ dimensions documented in the literature; these two factors were used for analyses. After controlling for site and gender, regression analyses revealed that neither easy/difficult temperament (p = .098,  = .109) nor time-to-warm-up temperament (p = .572,  = -.037) was predictive of distress. There was a significant treatment condition and time-to-warm-up temperament interaction, b = .0011, SE = .0005, p = .0254, such that distraction decreased distress in infants that were slower to warm up, or warmed up neither slowly nor quickly. No other significant distraction x temperament interactions were found. Temperament was not found to impact infant distress during immunizations in this study but results speaking to whether temperament serves as a moderator of the relation between distraction and distress were mixed. Results suggest that temperament is a factor that warrants closer attention when examining how infants respond to interventions around pain. INDEX WORDS: Infants, Temperament, Procedural pain, Distraction, Immunizations TEMPERAMENT AS A PREDICTOR OF INFANT IMMUNIZATION DISTRESS AND RESPONSE TO TREATMENT