Figures
Study flow diagram. IQR=interquartile range.
Function outcomes at baseline and 12-month follow-up to illustrate the main effect of treatment and treatment effect modification. Values represent unadjusted means and 95% confidence intervals. Graph A shows data for all participants. Graph B shows the outcome when the groups were stratified by median score on the Lumbar Spine Instability Questionnaire (LSIQ). Participants with an LSIQ score of 9 or greater (ie, high instability) are described as “positive” (+ve), and those with an LSIQ score of less than 9 are described as “negative” (−ve) on the questionnaire.
Lumbar Spine Instability Questionnaire
Tables
Description of Candidate Baseline Predictorsa
↵a SWT=Shuttle Walk Test, IPAQ=International Physical Activity Questionnaire, LSIQ=Lumbar Spine Instability Questionnaire, PSEQ=Pain Self-Efficacy Questionnaire, CSQ=Coping Strategies Questionnaire, PASS-20=Pain Anxiety Symptom Scale (short form).
Baseline Characteristics of Participantsa
↵a Continuous data are mean (SD); categorical data are n (%). CSQ=Coping Strategies Questionnaire (0 [“good coping strategy”]−36 [“worst coping strategy”]), Örebro questionnaire=Örebro Low Back Pain Screening Questionnaire (11 [“low risk of pain becoming persistent”]−192 [“high risk of pain becoming persistent”]), PASS-20 total score=Pain Anxiety Symptom Scale total score (0 [“low anxiety”]−100 [“high anxiety”]), PSEQ=Pain Self-Efficacy Questionnaire (0 [“high fear avoidance”]−100 [“no fear avoidance”]), IPAQ=International Physical Activity Questionnaire (metabolic equivalent minutes per week), LSIQ=Lumbar Spine Instability Questionnaire (0 [“no instability”]−15 [“high instability”]), NRS=pain numeric rating scale (0 [“no pain”]−10 [“worst pain imaginable”]), PSFS=Patient-Specific Functional Scale (0 [“unable to perform activity”]−10 [“able to perform activity at preinjury level”]), RMDQ-24=24-item Roland-Morris Disability Questionnaire (0 [“no disability”]−24 [“high disability”]).
Results of Univariate Testing of the Dichotomized Predictor Variables on Function Scoresa
↵a Values are nonstandardized point estimates (95% confidence interval) and associated P value for the effect of the predictor, the main effect of treatment group, and the interaction between predictor and treatment group on function scores. The reference category for the predictor term is a score greater than or equal to the median and for group term is the motor control group. Positive interaction terms for PSFS (function) outcomes and negative interaction terms for pain outcomes indicate a better response to graded activity exercises in participants with lower scores on the predictor variable. LSIQ=Lumbar Spine Instability Questionnaire, CSQ=Coping Strategies Questionnaire, PASS-20=Pain Anxiety Symptom Scale, Örebro questionnaire=Örebro Low Back Pain Screening Questionnaire, IPAQ=International Physical Activity Questionnaire, PSEQ=Pain Self-Efficacy Questionnaire, PSFS=Patient-Specific Functional Scale. Highlighted cells are statistically significant interactions (P<.05).
Adjusted Function (Patient-Specific Functional Scale) Treatment Effects (95% Confidence Interval) in Subgroup Positive and Subgroup Negative Participants for the Statistically Significant Predictors Onlya
↵a LSIQ=Lumbar Spine Instability Questionnaire (0 [“no instability”]−15 [“high instability”]), CSQ=Coping Strategies Questionnaire (0 [“good coping strategy”]−36 [“worst coping strategy”]), PASS-20 total score=Pain Anxiety Symptom Scale total score (0 [“low anxiety”]−100 [“high anxiety”]), Örebro questionnaire=Örebro Low Back Pain Screening Questionnaire (11 [“low risk of pain becoming persistent”]−192 [“high risk of pain becoming persistent”]). Highlighted values are statistically significant (P<.05).
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