Benefits and harms of Spinal Manipulative Therapy for treating recent and persistent nonspecific neck pain: a systematic review with meta-analysis

OBJECTIVE: To estimate the benefits and harms of cervical spinal manipulative therapy (SMT) for treating neck pain. DESIGN: Intervention systematic review with meta-analysis of randomized controlled trials (RCTs). LITERATURE SEARCH: We searched the MEDLINE, Cochrane CENTRAL, EMBASE, CINAHL, PEDro, Chiropractic Literature Index bibliographic databases, and grey literature sources, up to June 6, 2022. STUDY SELECTION CRITERIA: RCTs evaluating SMT compared to guideline-recommended and non-recommended interventions, sham SMT, and no intervention for adults with neck pain were eligible for our systematic review. Pre-specified outcomes included pain, range of motion, disability, health-related quality of life. DATA SYNTHESIS: Random-effects meta-analysis for clinically homogenous RCTs at short-term and long-term outcomes. Risk of bias was assessed using the Cochrane Risk-of-Bias 2.0 Tool. We used the Grading of Recommendations Assessment Development and Evaluation approach to judge the certainty of evidence. RESULTS: We included 28 RCTs. There was very low to low certainty evidence that SMT was more effective than recommended interventions for improving pain at short-term (standardized mean difference [SMD] 0.66; confidence interval [CI] 0.35 to 0.97) and long-term (SMD 0.73; CI 0.31 to 1.16), and for reducing disability at short-term (SMD 0.95; CI 0.48 to 1.42) and long-term (SMD 0.65; CI 0.23 to 1.06). Transient side effects only were found (e.g., muscle soreness). CONCLUSION: There was very low certainty evidence supporting cervical SMT as an intervention to reduce pain and improve disability in people with neck pain.