Table 1 Methodological appraisal tool for LBP prevalence studies (adapted) [15]

 1. At least 1 of the following must apply in the study: an entire target population, randomly selected sample or sample stated to represent the target population.

 2. At least 1 of the following: reasons for non-response described, non-responders described, comparison of responders and non-responders, or comparison of sample and target population.

 3. Response rate, and if applicable, drop-out rate reported

 4. Were the data primary data of LBP, or was it taken from a survey not specifically designed for that purpose?

 5. Were the data collected from each subject directly or were they collected from a proxy?

 6. Was the same mode of data collection used for all subjects?

 7. At least 1 of the following in case of:

 a) Questionnaire: a validated questionnaire or at least tested for reproducibility?

 b) Interview: interview validated, tested for reproducibility, or adequately described and standardized?

 c) Examination: examination validated, tested for reproducibility, adequately described and standardized?

 8. Was there a precise anatomic delineation of the lumbar area or reference to an easily obtainable article that contains such specification?

 9. Was there further useful specification of the definition of LBP, or question(s) put to study subjects quoted such as frequency, duration, or intensity, and character of the pain. Or was there reference to an easily obtainable article that contains such specification?

 10. Were the recall periods clearly stated: e.g. 1 week, 1 month, lifetime?