Table 2.

Modified Downs and Black quality checklist to assess measurement of PA in LBP populations

	Score
Reporting
1. Is the hypothesis/aim/objective of the study clearly described?	1
2. Are the main physical activity outcomes to be measured clearly described in the “Introduction” or “Methods” section?	1
3. Are the characteristics of the patients included in the study clearly described?	1
4. Are the physical activity measurements of interest clearly described?	1
5. Are the distributions of principal confounders in each group of subjects to be compared clearly described?	1
6. Are the main physical activity findings of the study clearly described?	1
7. Does the study provide estimates of the random variability in the physical activity data for the main LBP outcomes?	1
8. Have the characteristics of patients lost to follow-up been described?	1
9. Have actual probability values been reported (e.g. 0.035 rather than <0.05) for the main outcomes except where the probability value is less than 0.001?	1
External validity
10. Were the subjects asked to participate in the study representative of the entire population from which they were recruited?	1
11. Were those subjects who were prepared to participate representative of the entire population from which they were recruited?	1
Internal validity
12. If any of the results of the study were based on “data dredging”, was this made clear?	1
13. In trials and cohort studies, do the analyses adjust for different lengths of follow-up of patients, or in case–control studies, is the time period between the physical activity measurement and outcome the same for cases and controls?	1
14. Were the statistical tests used to assess the relationship between the LBP outcome measure and physical activity outcomes appropriate?	1
15. Was compliance with the physical activity measurement/s reliable?	1
16. Were the main physical activity outcome measures used accurate (valid and reliable)?	1
Confounding (selection bias)
17. Were the patients in different physical activity intervention groups (trials and cohort studies) or were the cases and controls (case–control studies) recruited from the same population?	1
18. Were study subjects in different physical activity intervention groups (trials and cohort studies) or were the cases and controls (case–control studies) recruited over the same period of time?	1
19. Were study subjects randomised to physical activity intervention groups?	1
20. Was the randomised intervention assignment concealed from both patients and health care staff until recruitment was complete and irrevocable?	1
21. Was there adequate adjustment for confounding factors between physical activity and LBP in the analyses from which the main findings were drawn?	1
22. Were losses of patients to follow-up taken into account?	1
Power
23. Did the study have sufficient power to detect a clinically important effect where the probability value for a difference being due to chance is less than 5%?	5
Total	27