| Supported by a Stanford Medical Scholars Research Fellowship (to Ms Hua). Data access for this project was provided by the Stanford Center for Population Health Sciences Data Core. The Population Health Sciences Data Core is supported by a National Institutes of Health National Center for Advancing Translational Sciences Clinical and Translational Science Award (UL1 TR001085) and internal Stanford funding. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
| Conflicts of interest: None disclosed.