Table 1 Inclusion and exclusion criteria defined by the PICO format used in the selection process to identify relevant publications

Population

Participants of any age: with a scar or keloid or hypertrophic scar

Post-acne scarring, animal and in vitro studies

Intervention

Local management with needling, dry needling or acupuncture, combination of local needling, or dry needling or acupuncture with distal acupuncture

Traditional Chinese Medicine (TCM), wet needling, microneedling, radiofrequency microneedling, trigger point (TrPs) / myofascial trigger point (MTrPs) dry needling beyond scar area, non-therapeutic dry needling, needling with electrical stimulation, electroacupuncture

Comparator

Trials in which the control subjects underwent other conservative treatment (e.g. physical modalities) for scar or did not receive any treatment.

Trials assessing intervention costs, adverse effects only, surgical treatment

Objective*

Changes in pain associated with scar; scar pigmentation, vascularization pattern, shape/thickness, pliability, plasticity, itchiness

Studies on pain/symptoms unrelated to scar / keloid and studies which did not use any scar assessment prior to and after dry needling

Publication type

Full-text research articles in English (randomized controlled trials, clinical trials, case reports, case series, case control studies)

Abstracts, posters, conference proceedings, letters, protocols, reviews (also meta-analyses) and non-clinical trials