Text and Data Mining valid from 2019-12-01
Received: 15 April 2019
Accepted: 20 November 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: The study protocol was approved by the Independent Scientific Advisory Committee (ISAC) for MHRA Database Research (protocol number: 16_030R). CPRD has ethical approval for data collection without individual participant consent under section 251.
: The authors declare that they have no competing interests.