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

To estimate the benefits and harms of cervical spinal manipulative therapy (SMT) for treating neck pain. Intervention systematic review with meta-analysis of randomized controlled trials (RCTs). We searched the MEDLINE, Cochrane CENTRAL, EMBASE, CINAHL, PEDro, Chiropractic Literature Index bibliographic databases, and grey literature sources, up to June 6, 2022. 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. 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. 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). There was very low certainty evidence supporting cervical SMT as an intervention to reduce pain and improve disability in people with neck pain.