title: Differences in comorbidities on low back pain and low back related leg pain.
abstract: OBJECTIVE
  Investigate the influence of external factors such as depression and BMI among subjects with primary severe low back pain (LBP) and low back related leg pain (LBLP).
  
  
  BACKGROUND
  The report of disability in patients with LBP may be significantly influenced by confounding and moderating variables. No similar studies have examined the influence of these factors on LBLP.
  
  
  METHODS
  This study included 1,448 consecutive subjects referred to a tertiary spine clinic. Unconditional binary logistic regression was used to determine the influence of comorbidities on the relationship between self-reported back and leg pain. A change in estimate formula was used to quantify this relationship.
  
  
  RESULTS
  Among those subjects with primary LBP the unadjusted odds ratio was 8.58 (95% CI 4.87, 15.10) and when adjusting for BMI, depression and smoking was 5.94 (95% CI 3.04, 11.60) resulting in a 36.7% change due to confounding by these comorbidities. Among those with primary LBLP, the unadjusted odds ratio was 4.49 (95% CI 2.78, 7.27) and when adjusting for BMI and depression was 4.60 (95% CI 2.58, 8.19) resulting in a 1.7% change due to confounding by these comorbidities.
  
  
  CONCLUSIONS
  The disability statuses of the patients with primary LBP in this study were more significantly affected by comorbidities of BMI, depression and smoking than patients with report of LBLP. However, these comorbidities contribute little to the relationship of primary low back related leg pain and Oswestry scores ≥ 40.
authors.affiliation: Department of Community and Family Medicine, Duke University, Durham, North Carolina, USA. adam.goode@duke.edu
authors.forename: Adam
authors.initials: A
authors.lastname: Goode
authors.forename: Chad
authors.initials: C
authors.lastname: Cook
authors.forename: Christopher
authors.initials: C
authors.lastname: Brown
authors.forename: Robert
authors.initials: R
authors.lastname: Isaacs
authors.forename: Matthew
authors.initials: M
authors.lastname: Roman
authors.forename: William
authors.initials: W
authors.lastname: Richardson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D003863:Depression / Q000453:epidemiology / Q000209:etiology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D016015:Logistic Models; D017116:Low Back Pain / Q000150:complications / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010147:Pain Measurement; D012372:ROC Curve; D012307:Risk Factors; D011795:Surveys and Questionnaires; D055815:Young Adult