Table 2 Quality checklist

Representativeness

Quality of data

Definition of LBP

Response rates in relation to invited study sample at baseline.

Sample sizes

N/% response at all surveys based on number of participants at first survey

At least one of the following: Whole target population; Randomly selected sample; or Sample stated to represent general population

At least one of the following: Reasons for non response described; Non-responders described; Comparison responders-non-responders; or Comparison of sample and target population

Same mode of data collection for all subjects, and all surveys

Same definition(s) of LBP outcome variable used for all subjects at all survey

At least one of the following: Questionnaires, diaries, or interviews validated; Tested for reproductibility or Tested in pilot study

Precise anatomical delineation of lumbar area; or Reference to easily obtainable article that contains such specification

Further specification of definition of LBP; Questions put to study subjects quoted; or Reference to easily obtainable article that contains such specification

Recall periods specified

Quality score: Number of ‘Yes’/Number of relevant items

If new study subjects invited, response rates calculated based on number of invited participants at each survey

(Yes/No)

(Yes/No)

(Yes/No)

(Yes/No)

(Yes/No)

(Yes/No)

(Yes/No)

(Yes/No)