Table 2.

Criteria list of methodological quality assessment of randomized controlled trials (RCTs) [22]

1. Study population (30 points)

a) Description of inclusion and exclusion criteria (1 point). Restriction to a homogeneous study population (1 point)

b) Comparability of relevant baseline characteristics: duration of complaint (1 point), value of outcome measures (1 point), age (1 point), recurrences (1 point), and radiating complaints/associated symptoms (1 point)

c) Description of the randomization procedure (2 points). Randomization procedure which excluded bias, i.e. random numbers table (2 points)

d) Description of dropouts for each group and their reasons (3 points)

e) Loss to follow-up: less than 20 % loss to follow-up (2 points), OR less than 10 % loss to follow-up (4 points)

f) Sample size: greater than 50 subjects in the smallest group after randomization (6 points), OR greater than 100 subjects in the smallest group after randomization (12 points)

2. Interventions (30 points)

g) Correct description of the manual intervention (5 points). All interventions described (5 points)

h) Pragmatic study: comparison with an existing treatment modality (5 points)

i) Co-interventions avoided in the design of the study (5 points)

j) Comparison with a placebo control group (5 points)

k) Mention of the experience of the therapist (5 points)

3. Measurement of effect (30 points)

l) Placebo controlled studies: patients blinded (3 points), blinding evaluated and fully successful (2 points) OR Pragmatic studies: patients fully naive, evaluated and fully successful (3 points), time restriction of no manual treatments for at least 1 year (2 points)

m) Outcome measures: pain assessment (2 points), global measure of improvement (2 points), functional status (2 points), spinal mobility (2 points), medical consumption (2 points)

n) Each blinded outcome measure mentioned under item M earns 2 points

o) Analysis of post-treatment data (3 points), inclusion of a follow-up period longer than 6 months (2 points)

4. Data presentation and analysis (10 points)

p) Intention-to-treat analysis when loss to follow-up is less than 10 % OR intention-to-treat analysis as well as worst-case analysis for missing values when loss to follow-up is greater than 10 % (5 points)

q) Corrected presentation of the data: mean or median with a standard deviation or percentiles for continuous variables (5 points)