title: Quantification of a meaningful change in low back functional impairment.
abstract: METHODS
  Repeated measures study design.
  
  
  OBJECTIVE
  Determine a meaningful change in low back functional impairment as measured with the lumbar motion monitor.
  
  
  BACKGROUND
  A quantitative functional performance probability (P(n)) measure has been developed and is scored from 0.00 to 1.00. Previous research has shown that a 0.5 cut-off provides excellent sensitivity and specificity for identifying impaired and healthy low back function. However, a meaningful change in the P(n) measure has not been defined.
  
  
  METHODS
  The lumbar motion monitor was used to repeatedly measure P(n) in 3 groups of subjects including (1) asymptomatic, (2) recovering low back pain (LBP) and, (3) nonrecovering LBP. The asymptomatic group had 20 subjects. The recovering and nonrecovering LBP had 18 and 8 subjects, respectively. The asymptomatic group was tested 5 times at 1-week intervals. The 2 LBP groups were tested every 2 weeks for 3 months (6 evaluations).
  
  
  RESULTS
  The P(n) in the asymptomatic group did not significantly change over the observed period. On the basis of the variability in the asymptomatic group it was hypothesized that a meaningful change in P(n) was 0.14. The defined meaningful change was evaluated in 2 patient with LBP populations. The P(n) in the recovered LBP group significantly improved during the 3 month observation period and there was a corresponding reduction of symptoms. In the recovering LBP group the within subject standard deviation was 0.14 and all patients had at least 1 visit to visit change greater than 0.14. Furthermore, 11 of the 18 recovering patients with LBP had a meaningful change between the first 2 visits. In contrast, none of the nonrecovering LBP group had a meaningful change between the first 2 visits.
  
  
  CONCLUSIONS
  A meaningful change in P(n) was defined as 0.14.
authors.affiliation: Department of Integrated Systems Engineering, The Ohio State University, Columbus, 43210, USA. ferguson.4@osu.edu
authors.forename: Sue A
authors.initials: SA
authors.lastname: Ferguson
authors.forename: William S
authors.initials: WS
authors.lastname: Marras
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Burr
authors.forename: Stephen
authors.initials: S
authors.lastname: Woods
authors.forename: Ehud
authors.initials: E
authors.lastname: Mendel
authors.forename: Purnendu
authors.initials: P
authors.lastname: Gupta
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008297:Male; D010147:Pain Measurement; D011237:Predictive Value of Tests; D011336:Probability; D016059:Range of Motion, Articular; D020127:Recovery of Function; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult