Table 1.

Quality assessment tool, adapted from US national institutes of health [5].

	Yes	No*	Other**
1. Was the research question or objective in this paper clearly stated?	1	0	–
2. Was the study population clearly specified and defined?	1	0	–
3. Was the participation rate of eligible persons at least 50%	1	0	–
4. Were all the subjects selected or recruited from the same or similar populations (including the same time period)? Were inclusion and exclusion criteria for being in the study pre-specified and applied uniformly to all participants?	1	0	–
5. Was a sample size justification, power description, or variance and effect estimates provided?	1	0	–
6. For determinants that can vary in amount or level, did the study examine different levels of the determinant as related to the outcome? (e.g. categories of determinant, or determinant measured as a continuous variable)	1	0	–
7. Were the determinant measures (independent variables) clearly defined, valid, reliable, and implemented consistently across all study participants?	1	0	–
8. Were the outcome measures (dependent variables) clearly defined, valid, reliable, and implemented consistently across all study participants?	1	0	–

*Includes not reported and cannot determine.

**Not applicable.