The effectiveness of superficial versus deep dry needling or acupuncture for reducing pain and disability in individuals with spine-related painful conditions: a systematic review with meta-analysis.

: The purpose of this systematic review was to evaluate the effects of deep versus superficial dry needling or acupuncture on pain and disability for spine-related painful conditions. A secondary purpose was to account for the differences of needling location in relation to the painful area. : This PROSPERO (#CRD42018106237) registered review found 691 titles through a multi-database search. Following a comprehensive search, 12 manuscripts were included in the systematic review and 10 in the meta-analysis. Standardized mean differences (SMD) with 95% confidence intervals were calculated for pain and disability. : The included studies demonstrated an unclear to high risk of bias recommending a cautious interpretation of the results. A consistent effect supporting deep needling over superficial with an SMD of 0.585 [0.335, 0.835], < 0.001 from 10 articles for pain but a non-significant effect of 0.197 [-0.066, 0.461], = 0.14 from 2 studies for disability. A temporal examination was similar for effects on pain with an SMD of 0.450 [0.104, 0.796] immediately, 0.711 [0.375, 1.048] short-term (1 to 11 weeks), and 0.470 [0.135, 0.805] for time-points ≥12 weeks. Regionally, there was a greater effect needling the area of pain locally (SMD = 0.754) compared to remotely (SMD = 0.501). : Statistically significant between-group differences were observed favoring deep needling over superficial. Both superficial and deep needling resulted in clinically meaningful changes in pain scores over time. However, differences between groups may not be clinically meaningful. More high-quality trials are needed to better estimate the effect size of deep versus superficial needling while controlling for location and depth of the lesion. Level of evidence: 1a.