Seven studies (9 treatment arms; 542 people) assessed VE pain: 5 RCTs and 3 repeated measures studies. Thirteen reports (612 people) assessed IV insertion pain: 10 RCTs and 3 repeated measures studies.
The overall quality scores ranged from 13 to 20 out of a possible 26. Inter-rater agreement for the data extraction ranged from 97 to 100%.
VE insertion pain.
The validity scores for the 7 studies ranged from 15 to 20. Five of the studies were funded. The sample size ranged from 18 to 140 people.
All of the studies found that EMLA cream significantly reduced VE pain. The fail-safe N was 374. The effect sizes ranged from 0.68 to 1.76; the pooled effect size was 1.05 (95% CI: 0.92, 1.34). No significant heterogeneity was detected for either significance levels (P=0.37) or effect sizes (P=0.69). The only moderator variable that influenced the results was sample size: as the sample size increased, the significance level of the results decreased (correlation, r = -0.37, P=0.01).
IV insertion pain.
The validity scores ranged from 13 to 20. Six of the studies were funded. The sample size ranged from 12 to 119 people.
Thirteen of the fourteen treatment arms found that EMLA cream significantly reduced IV pain. The fail-safe N was 994. Significant heterogeneity was detected for significance levels (P=0.0002) and for effect sizes (P<0.0001). After the removal of 2 studies with extreme effect sizes, the author reported that the remaining treatment arms were statistically homogeneous (P=0.03). The study quality score influenced the results (-0.52): as the quality increased, the effect size decreased. The effect sizes for these 10 remaining studies ranged from 0.62 to 2.13; the pooled effect size was 1.04 (95% CI: 0.84, 1.46). The moderator variables did not appear to influence the results.
Studies with an EMLA application duration of 60 minutes or less had an effect size of 1.07 with no significant heterogeneity. Results for the 6 studies with an EMLA application time of greater than 60 minutes were statistically heterogeneous (P=0.004). Further exploration of potential sources of heterogeneity did not reveal the source of this difference.