Effectiveness of vibratory stimulation on needle-related procedural pain in children: a systematic review

The objective of this systematic review was to identify, evaluate and synthesize evidence of the effectiveness of vibratory stimulation to reduce needle-related procedural pain in children aged 18 years and younger.

Needle-related procedures (NRPs) are common medical procedures associated with pain. Children, in particular, experience unpredictable and severe pain in response to NRPs. The gate control theory is commonly used to countermeasure this pain. Based on this theory, various types of vibratory stimulation have been used to reduce pain in several clinical studies.

Participants were 0- to 18-year-old children who underwent NRPs for any condition. The intervention included any type of vibratory stimulation during the NRPs. The main outcome was pain measured on any pain scale, including both self-rated and observer-rated pain scales. The secondary outcomes were anxiety, the duration of the procedure and the success rate. All studies were randomized controlled trials (RCTs) or quasi-randomized trials published in English.

The search strategy aimed to identify both published and unpublished studies. A three-step search strategy was utilized in this review. An initial search of MEDLINE and CINAHL was undertaken, followed by a search for unpublished studies. Nine databases were used for the search in October 2017. Papers selected for retrieval were assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments. Any disagreements that arose between the reviewers were resolved through discussion. Quantitative data were extracted from papers included in the review using a standardized data extraction tool. Where possible, quantitative data were pooled in the statistical meta-analysis. All results were subject to double data entry. Effect sizes were expressed as risk ratios (for categorical data) and weighted mean differences (for continuous data), and their 95% confidence intervals were calculated for analysis.

Twenty-one RCTs involving 1727 children were identified. Blinding of the participants and those delivering the treatment was not achieved in all studies, introducing a potential risk of bias. Overall, the vibratory stimulation was significantly effective in reducing NRP pain in children as shown by measurement of self-rated pain outcomes (standardized mean difference [SMD]: -0.55, 95% confidence interval [CI]: -0.92 to -0.18) and observer-rated pain outcomes (SMD: -0.47, 95% CI: -0.76 to -0.18). Among secondary outcomes, the effect on the child's anxiety (SMD: -1.03, 95% CI: -1.85 to -0.20) was significant.

Vibratory stimulation was effective in reducing NRP pain in children; however, blinding was not possible in the trials. Moreover, heterogeneity was high. Therefore, the confidence in the evidence is low. Personal preference should be a priority when using vibratory stimulation in the clinical setting.