Table 3 Item-total correlations and Cronbach’s α if deleted for non-users

Question 1

Please rate the study on the adequacy of the presented hypothesis and rationale.

Question 2

Please rate the study on the classification of the outcome (e.g. disease status or quantitative trait).

Question 3

Please rate the study on the description of comparison groups (e.g. cases and controls).

Question 4

Please rate the study on the technical classification of the exposure (i.e. the genetic variant).

Question 5

Please rate the study on the non-technical classification of the exposure (i.e. the genetic variant).

Question 6

Please rate the study on the disclosure and discussion of sources of bias.

Question 7

Please rate whether the study was adequately powered.

Question 8

Please rate the study on description of planned analyses.

Question 9

Please rate the study on the statistical methods.

Question 10

Please rate the study on the description and test of all assumptions and inferences.

Question 11

Please rate the study on whether conclusions drawn by the authors were supported by the results and appropriate methods.