Table 2.

Quality assessment cohort studies (NIH)

	Basta et al.31	Burton et al.19	Davies et al.13	Fernando et al.30	Meguid et al.32	Oxenberg et al.21	van Hagen et al.23	Schmidt et al.29	Snelgrove et al.28	Wood et al.26	Ye et al.27	Zhang et al.24
Clear aim	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	No	Yes
Population defined	Yes	Yes	Yes	Yes	Yes	NR	Yes	Yes	Yes	Yes	Yes	Yes
Participation rate of >50%	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	No	Yes	Yes	Yes
Subjects recruited from the same population	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Sample size justification	NR	NR	NR	NR	NR	NR	NR	NR	NR	NR	NR	NR
Exposures of interest measured prior to outcome	No	No	No	No	No	NA	No	No	No	Yes	Yes	No
Sufficient time frame	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Different levels of exposure examined	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
Exposure measures defined	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Exposures assessed >1	Yes	No	No	No	No	No	No	No	No	No	No	No
Outcome measures clear	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes
Assessors blinded	No	No	No	No	No	No	No	No	No	No	No	No
Loss to follow-up <20%	No	CD	CD	CD	CD	CD	CD	CD	No	CD	CD	CD
Key potential confounders measured	Yes	CD	No	No	No	Yes	No	CD	No	CD	Yes	No

CD could not determine, NR not reported, NA not applicable