Table 1

Baseline Characteristics

SMT 0 (n = 95)SMT 6 (n=99)SMT 12 (n = 97)SMT 18 (n = 100)All (n=391)
Sociodemographic information
    Age (yr)40.9 (14.1)41.4 (14.8)41.8 (14.0)41.2 (13.8)41.3 (14.1)
    Female (%)4949495250
    Non-white or Hispanic (%)1418111615
    Married (%)3728413636
    College degree (%)5863515356
    Income < $20,000/ yr (%)3127192826
Smoker (%)17136811

Expectations
    Confidence in treatment success
        Spinal Manipulation (1-6 scale)*3.6 (1.2)3.8 (1.1)3.7 (1.2)3.8 (1.1)3.7 (1.2)
        Light massage (1-6 scale)*3.4 (1.2)3.5 (1.2)3.4 (1.2)3.5 (1.2)3.5 (1.2)
    Previous treatment
        Spinal Manipulation (%)7170747272
        Light massage (%)5256435451

Low back pain complaint
    Pain intensity (0-100 scale)52.2 (16.3)51.0 (18.2)51.6 (17.5)51.5 (16.8)51.6 (17.2)
    Functional disability (0-100 scale)45.2 (21.8)44.8 (24.0)46.1 (23.4)45.2 (21.845.3 (22.7)
    Pain unpleasantness (0-100 scale)41.7 (19.5)41.1 (21.1)40.3 (22.8)42.4 (22.241.4 (21.4)
    Days with pain (last 4 wk)24.8 (4.8)24.1 (5.5)23.3 (5.7)24.1 (4.6)24.1 (5.2)
    Days with disability (last 4 wk)7.4 (8.1)6.7 (7.5)6.8 (7.5)6.5 (7.2)6.8 (7.6)
    Duration (yr)11.6 (9.5)11.2 (9.8)11.7 (10.4)12.5 (9.5)11.8 (9.8)

Health status
    SF-12 physical health component43.0 (9.5)43.8 (8.9)44.3 (8.4)42.3 (8.8)43.3 (8.9)
    SF-12 mental health component50.2 (10.5)48.6 (10.5)47.6 (11.2)49.4 (9.6)48.9 (10.5)
    Health State (0-100 visual analog scale)70.1 (17.2)72.1 (13.8)73.5 (14.4)68.2 (17.4)70.9 (15.8)
    Other Comorbidity (%)5857525455

Fear-Avoidance Beliefs Questionnaire
    Work beliefs (0-100 scale)36.6 (23.2)32.0 (23.4)31.0 (18.9)32.2 (21.4)32.9 (21.8)
    Activity beliefs (0-100 scale)55.0 (20.1)53.8 (23.1)56.4 (17.7)58.8 (19.8)56.0 (20.3)

Oral medication use (times in last 4 wk)
    Prescription0.9 (3.6)0.3 (1.1)0.6 (2.6)0.3 (1.5)0.5 (2.4)
    Non-prescription7.6 (10.0)8.9 (10.8)9.5 (10.0)7.6 (9.4)8.4 (10.1)
Mean (SD) or percentage. SMT, spinal manipulation.

*Six-point Likert scale with 1 indicating lowest and 6 indicating highest confidence.
Lower scores favorable. Low back pain intensity and functional disability evaluated with Modified Von Korff scales.
Higher scores favorable. Short Form 12 Health Survey (SF-12) scores are standardized to the US general population (mean=50, SD=10).