Footnotes

• Funding This study was partially funded by grants UL1 RR025752 and R01 NS062153, both from the National Institutes of Health. The funder had no role in the preparation, review or approval of the manuscript. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

• Competing interests None.

• Provenance and peer review Commissioned; internally peer reviewed.

• ↵i Given the case-control design of the study, we focus on results presented in the OR scale, despite the advantages of the risk difference scale for causal inference. Risk difference calculations are not possible from case-control data without making additional assumptions, or relying on external information on the source population.