Adverse events and manual therapy: a systematic review

Objective: To explore the incidence and risk of adverse events with manual therapies.

Method: The main health electronic databases, plus those specific to allied medicine and manual therapy, were searched. Our inclusion criteria were: manual therapies only; administered by regulated therapists; a clearly described intervention; adverse events reported. We performed a meta-analysis using incident estimates of proportions and random effects models.

Results: Eight prospective cohort studies and 31 manual therapy RCTs were accepted. The incidence estimate of proportions for minor or moderate transient adverse events after manual therapy was approximately 41% (CI 95% 17-68%) in the cohort studies and 22% (CI 95% 11.1-36.2%) in the RCTs; for major adverse events approximately 0.13%. The pooled relative risk (RR) for experiencing adverse events with exercise, or with sham/passive/control interventions compared to manual therapy was similar, but for drug therapies greater (RR 0.05, CI 95% 0.01-0.20) and less with usual care (RR 1.91, CI 95% 1.39-2.64).

Conclusions: The risk of major adverse events with manual therapy is low, but around half manual therapy patients may experience minor to moderate adverse events after treatment. The relative risk of adverse events appears greater with drug therapy but less with usual care.