Association between chiropractic spinal manipulation and lumbar discectomy in adults with lumbar disc herniation and radiculopathy: retrospective cohort study using United States’ data

OBJECTIVES: Chiropractic spinal manipulative therapy (CSMT) and lumbar discectomy are both used for lumbar disc herniation (LDH) and lumbosacral radiculopathy (LSR); however, limited research has examined the relationship between these therapies. We hypothesised that adults receiving CSMT for newly diagnosed LDH or LSR would have reduced odds of lumbar discectomy over 1-year and 2-year follow-up compared with those receiving other care. DESIGN: Retrospective cohort study. SETTING: 101 million patient US health records network (TriNetX), queried on 24 October 2022, yielding data from 2012 query. PARTICIPANTS: Adults age 18–49 with newly diagnosed LDH/LSR (first date of diagnosis) were included. Exclusions were prior lumbar surgery, absolute indications for surgery, trauma, spondylolisthesis and scoliosis. Propensity score matching controlled for variables associated with the likelihood of discectomy (eg, demographics, medications). INTERVENTIONS: Patients were divided into cohorts according to receipt of CSMT. PRIMARY AND SECONDARY OUTCOME MEASURES: ORs for lumbar discectomy; calculated by dividing odds in the CSMT cohort by odds in the cohort receiving other care. RESULTS: After matching, there were 5785 patients per cohort (mean age 36.9±8.2). The ORs (95% CI) for discectomy were significantly reduced in the CSMT cohort compared with the cohort receiving other care over 1-year (0.69 (0.52 to 0.90), p=0.006) and 2-year follow-up (0.77 (0.60 to 0.99), p=0.040). E-value sensitivity analysis estimated the strength in terms of risk ratio an unmeasured confounding variable would need to account for study results, yielding point estimates for each follow-up (1 year: 2.26; 2 years: 1.92), which no variables in the literature reached. CONCLUSIONS: Our findings suggest receiving CSMT compared with other care for newly diagnosed LDH/LSR is associated with significantly reduced odds of discectomy over 2-year follow-up. Given socioeconomic variables were unavailable and an observational design precludes inferring causality, the efficacy of CSMT for LDH/LSR should be examined via randomised controlled trial to eliminate residual confounding.