Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2017 Sep 7;358:j3776. doi: 10.1136/bmj.j3776

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

PMC Copyright notice

graphic file with name tubs038798.f2.jpg — Fig 2 Time frame of case and control periods in case crossover study, 2009-14. The case crossover design only includes cases, ie, participants who experienced the outcome events (oral streptococcal infective endocarditis), and each case acted as his or her own control