Visit Frequency and Outcomes for Patients Using Ongoing Chiropractic Care for Chronic Low-Back and Neck Pain: An Observational Longitudinal Study

BACKGROUND. Chronic spinal pain is prevalent and long-lasting. Although provider-based nonpharmacologic therapies such as chiropractic care have been recommended, healthcare and coverage policies provide little guidance or evidence regarding long-term use of this care. OBJECTIVE. Determine relationships between visit frequency and outcomes for patients using ongoing chiropractic care for chronic spinal pain. STUDY DESIGN. Observational 3-month longitudinal study. SETTING. Data collected from patients of 124 chiropractic clinics in six US regions. METHODS. Examined the impact of visit frequency and patient characteristics on pain (pain 0–10 numerical rating scale) and functional outcomes (Oswestry Disability Index or ODI for low-back pain and Neck Disability Index or NDI for neck pain, both 0–100 scale) using hierarchical linear modeling (HLM) in a large national sample of chiropractic patients with chronic low-back pain (CLBP) and/or chronic neck pain (CNP). This study was approved by the RAND Human Subjects Protection Committee and registered under ClinicalTrials.gov Identifier: NCT03162952. RESULTS. 1,362 patients with CLBP and 1,214 with CNP were included in a series of HLM models. Unconditional (time-only) models showed patients on average had mild pain and function and significant, but slight improvements in these over the 3-month observation period: back and neck pain decreased by 0.40 and 0.44 points, respectively; function improved by 2.7 (ODI) and 3.0 points (NDI) (all p