1. 2021;24;E61-E74Visit Frequency and Outcomes for Patients Using Ongoing Chiropractic Care for Chronic Low-Back and Neck Pain: An Observational Longitudinal Study
   Observational Study
   Christine M. Goertz, PhD, Melony E. Sorbero, PhD, Eric L. Hurwitz, PhD, Sarah E. Edgington, MA, Patricia M. Herman, PhD, and Ian D. Coulter, PhD.

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: To determine the 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 6 United States regions.

METHODS: We examined the impact of visit frequency and patient characteristics on pain (pain 0-10 numeric rating scale) and functional outcomes (Oswestry Disability Index [ODI] for low-back pain and Neck Disability Index [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: One thousand, three hundred, sixty-two 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 < 0.001). Adding chiropractic visit frequency to the models revealed that those with worse baseline pain and function used more visits, but only visits more than once per week for those with CLBP were associated with significantly better improvement. These relationships remained when other types of visits and baseline patient characteristics were included.

LIMITATIONS: This is an observational study based on self-reported data from a sample representative of chiropractic patients, but not all patients with CLBP or CNP.

CONCLUSIONS: This 3-month window on chiropractic patients with CLBP and/or CNP revealed that they were improving, although slowly; may have reached maximum therapeutic improvement; and are possibly successfully managing their chronic pain using a variety of chiropractic visit frequencies. These results may inform payers when building coverage policies for ongoing chiropractic care for patients with chronic pain.

KEY WORDS: Chronic low back pain, chronic neck pain, spinal pain, physical function, hierarchical linear modeling, healthcare utilization, chiropractic visits, insurance coverage