A study protocol for a randomised controlled trial of ice to reduce the pain of immunisation

Background and objective Vaccine injections commonly cause iatrogenic pain. Ice may reduce pain. This is a study protocol for a prospective randomised controlled trial aiming to investigate the efficacy of ice packs to decrease vaccine-related pain in adults. Methods The intervention group (n = 45) will receive ice packs (0 degrees C) and the control group (n = 45) receive placebo cold packs (10 degrees C) on the injection site for 30 seconds prior to vaccination. Results The primary outcomes will test the hypothesis that applying an ice pack will significantly reduce pain of vaccination when compared with a cold pack. The primary dependent variable will be pain score recorded on a visual analogue scale. Secondary outcomes aim to assess potential adverse reactions. The main analysis of data will follow the intention-to-treat principle. The primary dependent variable will be compared using an independent t-test or a Mann-Whitney U test. Multivariable logistic regression analysis may be used. Discussion The trial may guide general practitioners in the use of ice packs to reduce injection-related pain in adults.