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Table 3 Results for primary outcome measures

From: The effect of changing movement and posture using motion-sensor biofeedback, versus guidelines-based care, on the clinical outcomes of people with sub-acute or chronic low back pain-a multicentre, cluster-randomised, placebo-controlled, pilot trial

  Activity limitation (RMDQ23: 0 to 100 scale) Activity limitation (PSFS: 0 to 100 scale) Pain intensity (QVAS: 0 to 100 scale)
Preplanned analysis - Clinical course*
Movement Biofeedback Group effect #    
Beta coefficient (95 % CI) −7.1(−12.6 to −1.6) p < 0.014 −10.3(−16.6 to −3.9) p = 0.001 −7.7(−13.0 to −2.4) p < 0.004
Group effect Intraclass Correlation Coefficients    
Clinics 0.00 0.04 0.00
Clinicians 0.00 0.00 0.00
Patients 0.50 0.37 0.55
Movement Biofeedback Group-by-time (per 100 days) effect #    
Beta coefficient (95 % CI) −3.5(−5.2 to −2.2) p < 0.001 −4.7(−7.0 to −2.5) p < 0.001 −4.8(−6.1 to −3.5) p < 0.001
Group-by-time effect Intraclass Correlation Coefficients    
Clinics 0.00 0.00 0.00
Clinicians 0.00 0.00 0.00
Patients 0.51 0.38 0.59
Analysis n= Sites = 8 Sites = 8 Sites = 8
Clinicians = 8 Clinicians = 8 Clinicians = 8
Participants = 106 Participants = 96 Participants = 106
Assessments = 644 Assessments = 524 Assessments = 650
Additional analysis - Unadjusted comparison at individual time points**
3-month outcomes    
Movement Biofeedback Group    
Mean (95 % CI) 40.1 (20.7 to 59.5) 40.0 (24.0 to 56.0) 39.5 (21.4 to 55.7)
Mean improvement from baseline (95 % CI) 11.4 (7.3 to 15.5) 18.9 (6.1 to 31.7) 22.1 (13.6 to 30.5)
n (%) of patients who improved by ≥30 % of baseline score 15 (43 %) 16 (55 %) 17 (49 %)
Analysis n= 35 29 35
Guidelines-based Care Group    
Mean (95 % CI) 53.7 (31.8 to 75.6) 58.0 (34.0 to 82.0) 54.5 (41.1 to 67.8)
Mean improvement from baseline (95 % CI) −1.6 (−8.4, 5.2) 1.3 (−8.7, 11.4) 9-4 (2.4 to 16.3)
n (%) of patients who improved by ≥30 % of baseline score 6 (16 %) 12 (40 %) 12 (32 %)
Analysis n= 37 30 37
Difference between group means # −13.0 (−18.5 to 7.5) −17.6 (−28.9 to −6.3) −12.7 (−20.2 to −5.1)
Comparison between groups of probability of improving by ≥30 % = risk ratio (95 % CI) 2.6 (1.2 to 6.0) 1.4 (0.8 to 2.4) 1.5 (0.8 to 2.7)
12 month outcomes    
Movement Biofeedback Group    
Mean (95 % CI) 31.3 (8.9 to 53.7) 31.0 (22.0 to 41.0) 33.1 (17.7 to 48.6)
Mean improvement from baseline (95 % CI) 19.7 (15.4 to 24.0) 28.1 (20.4 to 35.9) 27.5 (21.7 to 33.3)
n (%) of patients who improved baseline score by ≥30 % of baseline score 26 (60 %) 31 (78 %) 30 (68 %)
Analysis n= 43 40 44
Guidelines-based Care Group    
Mean (95 % CI) 47.7 (36.2 to 59.2) 54.0 (42.0 to 64.0) 56.2 (52.4 to 60.1)
Mean improvement from baseline (95 % CI) 1.5 (−4.2 to 7.2) 3.2 (−8.6 to 15.0) 5.4 (3.3 to 7.4)
n (%) of patients who improved baseline score by ≥30 % of baseline score 12 (25 %) 12 (32 %) 10 (21 %)
Analysis n= 47 38 48
Difference between group means ## −18.2 (−23.1 to −13.2) −24.9 (−34.7 to −15.2) −22.2 (−26.4 to −17.9)
Comparison between groups of probability of improving by ≥30 % = risk ratio (95 % CI) 2.4 (1.4 to 4.1) 2.5 (1.5 to 4.0) 3.3 (1.8 to 5.9)
  1. *Calculated by use of multilevel mixed-effects linear regression adjusted for baseline value of the outcome measure, age, gender, and duration of back pain episode (fixed effects) and treatment site, clinician and individual patient (random effects)
  2. **This pilot cluster trial was not powered for individual time point comparisons and therefore these unadjusted descriptive results were not tested for statistical difference
  3. #The main effect of group indicates the average difference between the groups across treatment and outcome time points. The time-by-group interaction effect indicates the average difference between the groups in the rate of change over time
  4. ##Difference between group means = Guidelines-based Care Group minus Movement Biofeedback Group. Analyses adjusted for clustering by site and robust 95 % confidence intervals used
  5. Crude risk ratio = Movement Biofeedback Group / Guidelines-based Care Group. These unadjusted confidence intervals should be cautiously interpreted, as they do not account for any baseline imbalances or clustering effects
  6. RMDQ-23 = Roland Morris Disability Questionnaire (23 item version) where low scores are better, PSFS = Patient Specific Functional Scale converted to a 0–100 scale where low scores are better, QVAS = Average of four pain intensity VAS scales where low scores are better