Table 5
Participant-reported secondary outcome measures
| Treatment group | Group difference | P value* | ||
|---|---|---|---|---|
| Chiropractic care | Integrated care | Chiropractic care minus integrated care | ||
| Low back disability (Roland Morris) [0 to 100; lower scores indicate less disability] | ||||
| Mean at baseline (SD) | 40.9 (21.3) | 38.1 (19.2) | ||
| Mean at week 4 (95% CI) | 30.3 (27 to 33.6) | 27.0 (23.7 to 30.2) | 3.07 (− 0.95 to 7.08) | 0.14 |
| Mean at week 12 (95% CI) | 19.9 (16.6 to 23.2) | 16.5 (13.3 to 19.7) | 3.66 (− 0.65 to 7.97) | 0.10 |
| Short term response summary (area under the curve minus baseline through week 12) | 3.36 (− 0.65 to 7.38) | 0.10 | ||
| Mean at week 26 (95% CI) | 24.6 (21.2 to 27.9) | 20.2 (16.9 to 23.4) | 4.05 (− 0.97 to 9.07) | 0.12 |
| Mean at week 52 (95% CI) | 25.6 (22.1 to 29) | 19.0 (15.7 to 22.3) | 6.54 (1.18 to 11.90) | 0.02 |
| Long term response summary (area under the curve minus baseline through week 52) | 4.62 (0.88 to 8.36) | 0.02 | ||
| Improvement [1 to 9; 1 = 100% Improvement, 9 = 100% Worse] | ||||
| Mean at week 4 (95% CI) | 3.9 (3.6 to 4.1) | 3.6 (3.3 to 3.8) | 0.31 (0.03, 0.60) | 0.03 |
| Mean at week 12 (95% CI) | 3.1 (2.9 to 3.4) | 2.8 (2.6 to 3.1) | 0.29 (− 0.04, 0.63) | 0.09 |
Short term response summary (Area under the curve through week 12) | 0.31 (0.01 to 0.61) | 0.04 | ||
| Mean at week 26 (95% CI) | 3.5 (3.2 to 3.8) | 3.1 (2.8 to 3.3) | 0.38 (0.08, 0.68) | 0.01 |
| Mean at week 52 (95% CI) | 3.6 (3.3 to 3.9) | 3.1 (2.8 to 3.3) | 0.37 (0.08, 0.65) | 0.01 |
| Long term response summary (area under the curve through week 52) | 0.41 (0.14 to 0.68) | < 0.01 | ||
| Medication use [days/week] | ||||
| Mean at baseline (SD) | 2.8 (2.4) | 2.9 (2.4) | ||
| Mean at week 4 (95% CI) | 2.3 (1.9 to 2.7) | 2.6 (2.2 to 3) | − 0.27 (− 0.77 to 0.24) | |
| Mean at week 12 (95% CI) | 1.8 (1.4 to 2.2) | 1.8 (1.4 to 2.2) | − 0.05 (− 0.63 to 0.52) | |
| Short term response summary (area under the curve minus baseline through week 12) | − 0.21 (− 0.71 to 0.30) | |||
| Mean at week 26 (95% CI) | 1.8 (1.4 to 2.2) | 2.2 (1.8 to 2.6) | − 0.44 (− 1.06 to 0.19) | |
| Mean at week 52 (95% CI) | 2.3 (1.9 to 2.8) | 1.9 (1.5 to 2.4) | 0.50 (− 0.17 to 1.17) | |
| Long term response summary (area under the curve minus baseline through week 52) | − 0.11 (− 0.58 to 0.36) | 0.65 | ||
| Quality of life (EuroQol) [− 0.109 to 1; higher scores indicate better quality of life] | ||||
| Mean at baseline (SD) | 0.76 (0.10) | 0.79 (0.06) | ||
| Mean at week 4 (95% CI) | 0.80 (0.78 to 0.82) | 0.81 (0.79 to 0.83) | − 0.01 (− 0.04 to 0.02) | |
| Mean at week 12 (95% CI) | 0.83 (0.81 to 0.85) | 0.85 (0.83 to 0.87) | − 0.02 (− 0.05 to 0.01) | |
| Short term response summary (area under the curve minus baseline through week 12) | − 0.01 (− 0.04 to 0.01) | |||
| Mean at week 26 (95% CI) | 0.81 (0.79 to 0.83) | 0.82 (0.80 to 0.84) | − 0.02 (− 0.04 to 0.01) | |
| Mean at week 52 (95% CI) | 0.82 (0.79 to 0.84) | 0.84 (0.82 to 0.86) | − 0.02 (− 0.05 to 0.004) | |
| Long term response summary (area under the curve minus baseline through week 52) | − 0.02 (− 0.04 to 0.003) | 0.09 | ||
| Satisfaction with care [1 to 7; 1 = Completely Satisfied, 7 = Completely Dissatisfied] | ||||
| Mean at week 4 (95% CI) | 2.1 (1.9 to 2.3) | 1.8 (1.6 to 2) | 0.34 (0.12, 0.57) | < 0.01 |
| Mean at week 12 (95% CI) | 2 (1.8 to 2.2) | 1.7 (1.5 to 1.9) | 0.33 (0.09, 0.56) | < 0.01 |
| Short term response summary (area under the curve minus baseline through week 12) | 0.34 (0.11 to 0.56) | < 0.01 | ||
| Mean at week 26 (95% CI) | 2.3 (2.1 to 2.5) | 1.9 (1.7 to 2.1) | 0.38 (0.08, 0.68) | 0.01 |
| Mean at week 52 (95% CI) | 2.2 (2 to 2.4) | 1.8 (1.6 to 2) | 0.37 (0.08, 0.65) | 0.01 |
| Long term response summary (area under the curve through week 52) | 0.38 (0.16 to 0.59) | < 0.01 | ||
| Low back symptom frequency [0 to 5; 0 = none of the time, 5 = all of the time] | ||||
| Mean at baseline (SD) | ||||
| Mean at week 4 (95% CI) | 3.11 (2.9 to 3.32) | 2.83 (2.62 to 3.04) | 0.28 (− 0.01 to 0.58) | 0.06 |
| Mean at week 12 (95% CI) | 2.38 (2.17 to 2.59) | 2.02 (1.81 to 2.23) | 0.36 (0.06 to 0.66) | 0.02 |
Short term response summary (Area under the curve minus baseline through week 12) | 0.31 (0.07 to 0.56) | 0.01 | ||
| Mean at week 26 (95% CI) | 2.68 (2.47 to 2.9) | 2.33 (2.12 to 2.54) | 0.35 (0.05 to 0.66) | 0.02 |
| Mean at week 52 (95% CI) | 2.41 (2.19 to 2.64) | 1.95 (1.74 to 2.16) | 0.46 (0.16 to 0.77) | 0.003 |
| Long term response summary (area under the curve through week 52) | 0.38 (0.15 to 0.60) | 0.001 | ||
| Leg symptom frequency [0 to 5; 0 = none of the time, 5 = all of the time] | ||||
| Mean at baseline (SD) | ||||
| Mean at week 4 (95% CI) | 1.1 (0.92 to 1.28) | 1.03 (0.85 to 1.21) | 0.07 (− 0.19 to 0.32) | |
| Mean at week 12 (95% CI) | 0.77 (0.58 to 0.95) | 0.66 (0.49 to 0.84) | 0.1 (− 0.15 to 0.36) | |
Short term response summary (Area under the curve minus baseline through week 12) | 0.08 (− 0.13 to 0.29) | |||
| Mean at week 26 (95% CI) | 0.94 (0.75 to 1.12) | 0.87 (0.69 to 1.05) | 0.07 (− 0.2 to 0.33) | |
| Mean at week 52 (95% CI) | 1.04 (0.85 to 1.24) | 0.79 (0.6 to 0.97) | 0.26 (− 0.01 to 0.52) | |
Long term response summary (Area under the curve through week 52) | 0.12 (− 0.06 to 0.31) | 0.19 | ||
| Any missed work days due to back problem in past month [%] | ||||
| Percentage at baseline (n) | 36.3 (36) | 36.6 (37) | ||
| Percentage at week 4 (95% CI) | 23.5 (16.4 to 30.5) | 24.2 (17.4 to 31.0) | − 0.7 (− 10.2 to 8.7) | |
| Percentage at week 12 (95% CI) | 17.5 (11.0 to 24.1) | 13.0 (8.2 to 17.8) | 4.5 (− 3.1 to 12.1) | |
| Percentage at week 26 (95% CI) | 15.2 (9.4 to 21.1) | 16.6 (10.6 to 22.6) | − 1.3 (− 9.1 to 6.5) | |
| Percentage at week 52 (95% CI) | 17.3 (10.5 to 24.1) | 16.1 (9.9 to 22.3) | 1.2 (− 7.6 to 10.0) | |
| Number of missed work days due to back problem in past month [0–31 days] | ||||
| Mean at baseline (SD) | 6.0 (4.9) | 6.6 (6.8) | ||
| Mean at week 4 (95% CI) | 6.09 (3.56 to 8.62) | 4.49 (3.13 to 5.85) | 1.60 (− 1.29 to 4.49) | |
| Mean at week 12 (95% CI) | 2.18 (1.35 to 3.01) | 3.84 (1.55 to 6.12) | − 1.65 (− 4.12 to 0.81) | |
| Mean at week 26 (95% CI) | 6.23 (1.33 to 11.14) | 5.38 (0.54 to 10.21) | 0.86 (− 6.07 to 7.78) | |
| Mean at week 52 (95% CI) | 3.16 (1.98 to 4.33) | 6.11 (0.20 to 12.02) | − 2.96 (− 9.03 to 3.11) | |
| Any reduced activity days due to back problem in past month [%] | ||||
| Percentage at baseline (n) | 74.0 (74) | 72.2 (73) | ||
| Percentage at week 4 (95% CI) | 54.4 (45.7 to 63.1) | 64.8 (56.5 to 73.1) | − 10.4 (− 22.4 to 1.6) | |
| Percentage at week 12 (95% CI) | 41.3 (31.4 to 51.2) | 41.8 (32.9 to 50.8) | − 0.6 (− 13.9 to 12.8) | |
| Percentage at week 26 (95% CI) | 43.7 (34.7 to 52.7) | 37.1 (30.0 to 44.2) | 6.6 (− 4.4 to 17.6) | |
| Percentage at week 52 (95% CI) | 41.5 (32.6 to 50.4) | 34.7 (26.9 to 42.5) | 6.8 (− 4.5 to 18.2) | |
| Number of reduced activity days due to back problem in past month [0–31 days] | ||||
| Mean at baseline (SD) | 9.0 (8.2) | 8.4 (8.0) | ||
| Mean at week 4 (95% CI) | 6.05 (5.02 to 7.08) | 5.07 (4.19 to 5.95) | 0.98 (− 0.26 to 3.01) | |
| Mean at week 12 (95% CI) | 5.04 (3.10 to 6.99) | 4.22 (3.10 to 5.35) | 0.82 (− 1.37 to 3.01) | |
| Mean at week 26 (95% CI) | 4.58 (3.56 to 5.60) | 4.53 (3.55 to 5.51) | 0.05 (− 1.24 to 1.33) | |
| Mean at week 52 (95% CI) | 4.84 (3.36 to 6.33) | 4.53 (3.54 to 5.52) | 0.31 (− 1.34 to 1.96) | |
| Fear avoidance beliefs—work subscale [0–42; higher scores indicate greater fear avoidance beliefs] | ||||
| Mean at baseline (SD) | 9.13 (8.94) | 9.69 (8.47) | ||
| Mean at week 4 (95% CI) | 8.30 (7.15 to 9.45) | 7.53 (6.4 to 8.66) | 0.77 (− 0.84 to 2.38) | |
| Mean at week 12 (95% CI) | 7.10 (5.94 to 8.26) | 5.94 (4.82 to 7.06) | 1.16 (− 0.45 to 2.77) | |
| Short term response summary (area under the curve minus baseline through week 12) | 0.93 (− 0.46 to 2.31) | |||
| Mean at week 26 (95% CI) | 6.80 (5.62 to 7.98) | 5.65 (4.51 to 6.78) | 1.15 (− 0.48 to 2.79) | |
| Mean at week 52 (95% CI) | 6.60 (5.39 to 7.81) | 6.49 (5.34 to 7.64) | 0.11 (− 1.56 to 1.78) | |
| Long term response summary (area under the curve through week 52) | 0.84 (− 0.44 to 2.11) | 0.20 | ||
| Fear avoidance beliefs—physical activity subscale [0 to 24; higher scores indicate greater fear avoidance beliefs] | ||||
| Mean at baseline (SD) | 11.66 (5.42) | 11.63 (5.32) | ||
| Mean at week 4 (95% CI) | 9.03 (8.04 to 10.01) | 9.3 (8.33 to 10.27) | − 0.28 (− 1.66 to 1.11) | |
| Mean at week 12 (95% CI) | 7.54 (6.55 to 8.54) | 7.36 (6.39 to 8.33) | 0.18 (− 1.21 to 1.57) | |
Short term response summary (Area under the curve minus baseline through week 12) | − 0.09 (− 1.31 to 1.12) | |||
| Mean at week 26 (95% CI) | 7.71 (6.7 to 8.72) | 6.52 (5.53 to 7.5) | 1.20 (− 0.21 to 2.6) | |
| Mean at week 52 (95% CI) | 7.61 (6.57 to 8.64) | 7.22 (6.23 to 8.21) | 0.39 (− 1.04 to 1.82) | |
| Long term response summary (area under the curve through week 52) | 0.59 (− 0.55 to 1.72) | 0.31 | ||
| Self-efficacy [0 to 60; higher scores indicate greater self-efficacy] | ||||
| Mean at baseline (SD) | 48.0 (10.0) | 49.2 (8.7) | ||
| Mean at week 4 (95% CI) | 52.2 (50.9 to 53.6) | 52 (50.7 to 53.4) | 0.18 (− 1.70 to 2.07) | |
| Mean at week 12 (95% CI) | 54.4 (53 to 55.7) | 54.7 (53.4 to 56) | − 0.33 (− 2.22 to 1.57) | |
| Short term response summary (area under the curve minus baseline through week 12) | − 0.02 (− 1.67 to 1.63) | |||
| Mean at week 26 (95% CI) | 52.5 (51.2 to 53.9) | 53.2 (51.8 to 54.5) | − 0.63 (− 2.55 to 1.29) | |
| Mean at week 52 (95% CI) | 51.8 (50.4 to 53.2) | 53.8 (52.5 to 55.2) | − 1.99 (− 3.94 to − 0.04) | |
| Long term response summary (area under the curve through week 52) | − 0.82 (− 2.35 to 0.71) | 0.29 | ||
| Active pain coping strategies (pain management inventory) [5 to 25; higher scores indicate more frequent use] | ||||
| Mean at baseline (SD) | 17.3 (3.4) | 17.1 (3.6) | ||
| Mean at week 12 (95% CI) | 18.2 (17.6 to 18.9) | 19.0 (18.4 to 19.7) | − 0.8 (− 1.7 to 0.1) | 0.07 |
| Passive pain coping strategies (Pain Management Inventory) [6 to 30; higher scores indicate more frequent use] | ||||
| Mean at baseline (SD) | 13.8 (4.5) | 13.9 (3.9) | ||
| Mean at week 12 (95% CI) | 12.6 (12.0 to 13.2) | 11.7 (11.1 to 12.3) | 0.9 (0.1 to 1.7) | 0.036 |
| Kinesiophobia [17 to 68] (11 questions; 1 = Strongly Disagree—4 = Strongly Agree) | ||||
| Mean at baseline (SD) | 35.2 (6.3) | 33.2 (5.8) | ||
| Mean at week 12 (95% CI) | 29.7 (28.6 to 30.8) | 28.7 (27.6 to 29.8) | 1.0 (2.6 to − 0.6) | 0.20 |
Mean values adjusted for baseline except for improvement and satisfaction
*Long term response summary serves as the omnibus test p-value. If p > .05, p-values for short term response and individual time points are not computed