Comparable pain and distress outcome measures from the selected RCTs were used in a meta-analysis. For all outcome measures the intergroup standardized mean difference (SMD) with the corresponding 95% CI was calculated as effect size. Heterogeneity was determined by the I-squared (I2) statistic. Pooled estimates of the SMD were calculated using the random-effects model assuming that underlying heterogeneity exists, irrespective of whether the I2 statistic indicates heterogeneity, and to be conservative in our estimated 95% CI[8]. A forest plot analysis served to show the effects of music interventions on pain, anxiety and distress scores for the intervention and control groups.