Table 1. Descriptive characteristics of the study participants (N = 593)

Variable

n

Mean (SD)/%

Demographic

Age (mean)a

294

43.3 (12.4)

Sex, female (%)a

299

63.5

LBP characteristics

No leg pain (%)

593

39.3

Thigh pain (%)

593

22.3

Thigh and lower leg pain (%)

593

21.9

Lower leg pain (%)

>593

4.6

Co occurring pain in the neck or thoracic spine (%)

518

66.0

Visit to chiropractor for same problem previously, no (%)

593

53.7

Exposure. Patient's expectation at the 1st visit

Expectation pain will get better, 010 (mean)

579

7.9 (2.1)

Proportion of patients with a high expectation in that their pain will get better, dichotomized (%)

593

80.1

Effect modifiers

Pain intensity at 1st visit, 010 (mean)

580

5.4 (2.1)

EQ5D score baseline, 01 (mean)

575

0.69 (0.2)

MPI, 06 (mean)

Pain severity

576

3.4 (1.2)

Interference

576

2.8 (1.3)

Life control

576

3.5 (1.1)

Affective distress

576

2.7 (1.3)

Support

574

3.9 (1.7)

Punishing responses

507

1.0 (1.2)

Solicitous responses

507

2.6 (1.4)

Distracting responses

506

2.8 (1.5)

MPI cluster assignment (%)

Adaptive copers (AC)

186

37.3

Interpersonally distressed (ID)

118

23.6

Dysfunctional (DYS)

195

39.1

Health in general (%)

Excellent

35

5.9

Very good

189

31.9

Good

237

40.0

Somewhat

96

16.2

Poor

20

3.4

Activity level at work (%)

Heavy

37

9.4

Intermittent heavy/light

103

26.3

Walking/standing

102

26.0

Sitting

150

38.3

Outcome. Subjective improvement at the 4th visit

Pain intensity at 4th visit, 010 (mean)

590

3.0 (2.1)

Perceived improvement at 4th visit (%)

Definitely worse

3

0.5

Probably worse

8

1.4

Unchanged

37

6.3

Probably better

132

22.4

Definitely better

409

69.4

Note

                     n represents the number of individuals where data were available.

                     a Age and Sex were recorded at a later stage in the RCT and therefore only available for individuals who reported a definite improvement at the fourth visit.