title: Different minimally important clinical difference (MCID) scores lead to different clinical prediction rules for the Oswestry disability index for the same sample of patients.
abstract: BACKGROUND
  Minimal clinically important difference (MCID) scores for outcome measures are frequently used evidence-based guides to gage meaningful changes. There are numerous outcome instruments used for analyzing pain, disability, and dysfunction of the low back; perhaps the most common of these is the Oswestry disability index (ODI). A single agreed-upon MCID score for the ODI has yet to be established. What is also unknown is whether selected baseline variables will be universal predictors regardless of the MCID used for a particular outcome measure.
  
  
  OBJECTIVE
  To explore the relationship between predictive models and the MCID cutpoint on the ODI.
  
  
  METHODS
  Data were collected from 16 outpatient physical therapy clinics in 10 states.
  
  
  METHODS
  Secondary database analysis using backward stepwise deletion logistic regression of data from a randomized controlled trial (RCT) to create prognostic clinical prediction rules (CPR).
  
  
  METHODS
  One hundred and forty-nine patients with low back pain (LBP) were enrolled in the RCT. All were treated with manual therapy, with a majority also receiving spine-strengthening exercises.
  
  
  RESULTS
  The resultant predictive models were dependent upon the MCID used and baseline sample characteristics. All CPR were statistically significant (P < 001). All six MCID cutpoints used resulted in completely different significant predictor variables with no predictor significant across all models.
  
  
  CONCLUSIONS
  The primary limitations include sub-optimal sample size and study design.
  
  
  CONCLUSIONS
  There is extreme variability among predictive models created using different MCIDs on the ODI within the same patient population. Our findings highlight the instability of predictive modeling, as these models are significantly affected by population baseline characteristics along with the MCID used. Clinicians must be aware of the fragility of CPR prior to applying each in clinical practice.
authors.affiliation: Walsh University, North Canton, OH, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Schwind
authors.affiliation: Walsh University, North Canton, OH, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Learman
authors.affiliation: Walsh University, North Canton, OH, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: O'Halloran
authors.affiliation: Walsh University, North Canton, OH, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Showalter
authors.affiliation: Walsh University, North Canton, OH, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Cook
keywords: Clinical prediction rule; Low back pain; Minimal clinically important difference; Prognosis