The association between chiropractors' view of practice and patient encounter-level characteristics in Ontario, Canada: a cross-sectional study

Background: Chiropractors have diverse views of practice, but the impact on their patient profiles and treatment approaches remains unclear. We assessed the association between chiropractors' view of practice (unorthodox versus orthodox) and patient encounter-level characteristics among chiropractors who practice in Ontario, Canada.

Methods: We conducted a cross-sectional study using Ontario Chiropractic Observation and Analysis STudy (O-COAST) data. In O-COAST, Ontario chiropractors were randomly recruited from a list of registered chiropractors in 2015 and recorded up to 100 consecutive patient encounters. We classified chiropractors' response regarding their views of practice as unorthodox when viewing "vertebral subluxation as an encumbrance to health that is corrected to benefit overall well-being"; other views were considered orthodox. Patient encounter-level characteristics included: (1) non-musculoskeletal reason-for-encounter; (2) subluxation as diagnosis; (3) duration of encounter (log-transformed for modeling); (4) unimodal manipulative treatment; and (5) patient health characteristics (good health status, some activity limitations). We conducted multilevel logistic regression to assess the association between view of practice and aforementioned characteristics, accounting for potential confounders and clustering of encounters within chiropractors. The multilevel models had two levels (level 1-patient encounter level; level 2-chiropractor level), with level 1 patient encounters nested within level 2 chiropractors.

Results: We included 40 chiropractors (mean age = 43.4 years, SD = 11.5) and 3,378 chiropractor-patient encounters. The 2,332 unique patients identified had a mean age of 48.5 years (SD = 18.5). Chiropractors with unorthodox views had higher odds of having patients with a non-musculoskeletal reason-for-encounter (adjusted odds ratio (aOR) 16.5, 95% CI 3.2-84.0) and subluxation as diagnosis (aOR 63.0, 95% CI 4.2-949.1). Encounters of chiropractors with unorthodox views were 0.6 times shorter than those with orthodox views (95% CI 0.4-0.9). Chiropractor level explained 32%, 75%, and 49% of the variability in non-musculoskeletal reason-for-encounter, subluxation as diagnosis, and encounter duration, respectively. We observed no association between unorthodox view and unimodal manipulative treatment or patient health characteristics.

Conclusions: Chiropractors' unorthodox view of practice was associated with treating non-musculoskeletal conditions, subluxation as diagnosis, and shorter duration of encounter. Chiropractor level explained a high proportion of variability in these outcomes. Findings have implications for understanding chiropractic practice and informing interprofessional collaboration.