OBJECTIVE: To evaluate longitudinal cost outcomes of initial treatment strategies for new neck pain (NP) episodes among Medicare beneficiaries. DESIGN: Retrospective cohort study using Medicare Part A, B, and D claims data. SETTING: Not applicable. PARTICIPANTS: Medicare beneficiaries aged 65-99 years, continuously enrolled in Parts A, B, and D from 2018 to 2021, who experienced a new NP episode in 2019. INTERVENTIONS: Three cohorts were developed based on the index visit provider: chiropractic (spinal manipulative therapy [SMT]), primary care with prescription analgesics (PCP [+A]), and primary care without analgesics (PCP [-A], reference group). MAIN OUTCOME MEASURES: Medicare allowed costs for total and NP-related claims (Parts A and B), and medication claims (Part D) over 24 months from the index visit. RESULTS: Among 291,604 older adults with NP, most were White women with few comorbidities. Compared to PCP (-A), the SMT cohort had 6% (cost ratio, 0.94
95% CI, 0.93-0.95) lower total Medicare Part A costs, whereas the PCP (+A) cohort showed no difference. For NP-related Part A claims, PCP (+A) had 7% (0.93
95% CI, 0.88-0.98) lower costs, whereas SMT showed no difference. The SMT cohort had 6% (0.94
95% CI, 0.94-0.95) lower total Medicare Part B costs and 36% (0.64
95% CI, 0.64-0.65) lower NP-related costs, whereas PCP (+A) had 2% (1.02
95% CI, 1.01-1.02) higher total costs. The SMT had 2% (0.98
95% CI, 0.98-0.99) lower nonanalgesic and 13% (0.87
95% CI, 0.87-0.88) lower analgesic Part D costs
the PCP (+A) had 13% (1.13
95% CI, 1.12-1.14) higher nonanalgesic but 14% (0.86
95% CI, 0.86-0.87) lower analgesic costs. Propensity weighting balanced covariates among cohorts. CONCLUSIONS: For older adults with new NP episodes, initial SMT was associated with lower health care costs, particularly for Part A total and NP-related claims, with a less pronounced effect on Part B and D claims than PCP-related strategies. These findings suggest potential for health care savings based on the initial treatment choice.