Table 2.

Methodological Quality Scoring¹ for all studies

		Study
	Checklist item	1. [12]	2.[13]	3.[14]	4.[15]	5.[16]	6.[17]	7.[19]	8. [18]
1	Is there a rationale for the study?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
2	Is a clear study objective/goal defined?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
3	Are key elements of study design described (e.g. how were participants identified/recruited)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
4	Are the setting and selection criteria for the study population described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
5	Is the follow-up period appropriate?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
6	Are there any strategies to avoid loss to follow-up, or address missing data?	No	No	No	No	Yes	No	No	No
7	Is the sample size justified?	No	No	No	No	No	No	No	No
8	Is information presented about the measurement instruments used to measure the prognostic variable(s) and does this enable replication (through the use of standardised or valid measures)?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
9	Is the outcome selected and assessed appropriately?	Yes	Yes	No	No	Yes	No	Yes	Yes
10	Are the study sample described (demographic/clinical characteristics)?	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes
11	Is the final sample representative of the study's target population?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
12	Is loss to follow-up ≤ 20%? (If not, are there any significant differences between responders and non-responders to follow-up on baseline variables? If yes, have the implications been considered?)	Yes	Yes	No 28%	Yes	Yes	Yes	Yes	Yes
13	Are the main results reported (including prevalence of prognostic indicator(s) & outcome, strength of association, and statistical significance)?	Yes	Not fully	Not fully	Not fully	Yes	Not fully	Yes	Yes
14	Is the statistical analysis appropriate and described?	Yes	No	Yes	Yes	Yes	No	Yes	Yes
15	Were potential confounders and effect modifiers identified and accounted for (e.g. multivariate analysis)?	Yes	No	Yes	Yes	Yes	No	Yes	Yes
16	Do the findings support the authors' interpretations?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
17	Do the authors discuss study limitations (e.g. biases/generalisability)?	Yes	Yes	Yes	No	Yes	No	Yes	No
	Total Score	15	12	12	12	16	8	15	14

Scoring: Total number of yes answers gives overall score

0-10 = poor quality 11-14 = adequate quality 15-17 = high quality

¹ Based on a draft developed by a consensus group who met at the International Forum IX for Primary Care Research on Low Back Pain, in October 2007.