title: Effect of fear-avoidance beliefs of physical activities on a model that predicts risk-adjusted functional status outcomes in patients treated for a lumbar spine dysfunction.
abstract: METHODS
  Retrospective analysis of a prospective, longitudinal cohort study of 30 858 patients being treated for a lumbar spine dysfunction in outpatient physical therapy.
  
  
  OBJECTIVE
  To determine effect of adding a single-item screening variable classifying patients with elevated versus not-elevated scores of fear-avoidance beliefs of physical activities at intake, on a model predicting risk-adjusted functional status (FS) outcomes.
  
  
  BACKGROUND
  Outcomes must be risk-adjusted before making meaningful interpretations. Elevated fear-avoidance beliefs scores have been predictive of poor outcomes. But the importance of elevated fear-avoidance scores in a multivariable model predicting FS outcomes needs further study.
  
  
  METHODS
  Using retrospective analyses, predictive ability (R2) of multivariable linear regression models of discharge FS with and without classification by elevated versus not-elevated fear-avoidance scores were compared, while controlling for intake FS, age, symptom acuity, surgical history, gender, number of comorbidities, and payer. Percent variance controlled and beta coefficients (95% confidence intervals) of each variable in both models were compared. A split-half design was used for model cross-validation. Predictive ratios (predicted FS, divided by actual discharge FS) were assessed.
  
  
  RESULTS
  Adding fear-avoidance beliefs classification to the discharge FS model improved (P<.001) model predictive ability but only slightly (R2 without, and with, fear-avoidance classification, 0.2997 and 0.3010, respectively). Variables impacted models similarly (95% confidence intervals not different). Fear-avoidance classification added 0.2% data variance control to the existing model. Cross-validation was supported. Predictive ratios were 1.09 and 1.10, without and with fear-avoidance, respectively.
  
  
  CONCLUSIONS
  Although screening for elevated fear-avoidance beliefs of physical activities significantly improves the FS outcomes predictive model, the amount of additional meaningful interpretation of FS outcomes was minimal. Exploration of other clinically relevant variables designed to improve outcomes prediction is warranted.
  
  
  METHODS
  Prognosis, level 2c.
authors.affiliation: Focus On Therapeutic Outcomes, Inc, 551 Yopps Cove Road, White Stone, VA 22578, USA. dsailhart@verizon.net
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Hart
authors.forename: Mark W
authors.initials: MW
authors.lastname: Werneke
authors.forename: Daniel
authors.initials: D
authors.lastname: Deutscher
authors.forename: Steven Z
authors.initials: SZ
authors.lastname: George
authors.forename: Paul W
authors.initials: PW
authors.lastname: Stratford
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005239:Fear; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008159:Lumbar Vertebrae; D008875:Middle Aged; D008954:Models, Biological; D009043:Motor Activity / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology; D012189:Retrospective Studies; D012307:Risk Factors; D013122:Spinal Diseases / Q000503:physiopathology* / Q000523:psychology* / Q000628:therapy; D016896:Treatment Outcome; D055815:Young Adult