Quantification of a meaningful change in low back functional impairment.
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.
Ferguson
Sue A
SA
Department of Integrated Systems Engineering, The Ohio State University, Columbus, 43210, USA. ferguson.4@osu.edu
Marras
William S
WS
Burr
Deborah L
DL
Woods
Stephen
S
Mendel
Ehud
E
Gupta
Purnendu
P
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