title: Differences among primary care patients with different mechanical patterns of low back pain: a cross-sectional investigation.
abstract: To characterise and compare a persistent low back pain (LBP) population based on 4 clinical pain patterns.
  
  
  
  Cross-sectional analysis of patient-reported data.
  
  
  
  Patients from 220 primary care practitioners in 3 cities in Ontario, Canada.
  
  
  
  1020 individuals seeking LBP care.
  
  
  
  LBP symptoms lasting 1½-12 months, or unmanageable recurrent symptoms; ages 18+years.
  
  
  
  pregnant/1-year postpartum; involved in active litigation or motor vehicle injury; emergent spinal presentations; pain disorder diagnosis; work injury claim; or constant symptoms persisting >12 months postonset.
  
  
  
  Hall pain pattern subgroups: back dominant pain aggravated by flexion (P1) or extension (P2), or leg dominant constant (P3) or intermittent (P4) pain (multinomial logistic outcome; referent: P1).
  
  
  
  Groups P1 and P2 had the highest proportion of women. P2 and P4 had higher mean ages and comorbidity counts. P3 and P4 had higher proportions of overweight/obese individuals and lower general health scores. Adjusted models: being male and overweight/obese was associated with increased odds of being in P3 (OR 1.64 (95% CI 1.10 to 2.46), and OR 1.74 (1.13 to 2.68), respectively) and P4 (OR 1.87 (1.11 to 3.15) and OR 1.91 (1.06 to 3.42), respectively), and increasing age with increased odds of being in P2 (OR 1.02 (1.01 to 1.03)) and P4 (OR 1.06 (1.04 to 1.08)). Increasing comorbidity count was associated with increased odds of being in P2 (OR 1.14 (1.0 to 1.3)), and better general health scores with decreased odds of being in P3 (OR 0.40 (0.18 to 0.93)).
  
  
  
  This is the first study to examine the 'Hall system' in a non-rehab primary care population. Subgroups classified according to this system appear to have distinct profiles. Further research is needed to better characterise and determine the prognostic implication of these clinically derived subgroups.
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Della Mora
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|Health Care and Outcomes Research, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.|Arthritis Program, University Health Network, Toronto, Ontario, Canada.|Faculty of Medicine, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Anthony V
authors.initials: AV
authors.lastname: Perruccio
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|Health Care and Outcomes Research, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.|Arthritis Program, University Health Network, Toronto, Ontario, Canada.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
authors.affiliation: Arthritis Program, University Health Network, Toronto, Ontario, Canada.|Faculty of Medicine, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Y Raja
authors.initials: YR
authors.lastname: Rampersaud
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D050177:Overweight; D010147:Pain Measurement / Q000379:methods*; D010342:Patient Acceptance of Health Care / Q000523:psychology / Q000706:statistics & numerical data*; D011320:Primary Health Care; D055815:Young Adult
keywords: EPIDEMIOLOGY; PRIMARY CARE; low back pain; pain pattern