Funding for this research was provided by:
Clinical Research Bursary from Cancer Research-UK (C54914/A20558)
a joint scholarship from Queen's University of Belfast and the Chinese Scholarship Council (CSC201708060458)
Received: 27 February 2019
Accepted: 3 October 2019
First Online: 29 October 2019
Ethics approval and consent to participate
: The study protocol was approved by the Independent Scientific Advisory Committee for Medicines and Healthcare products Regulatory Agency Database Research (protocol number: 15_096RMn3). This study is based in part on data from the CPRD obtained under licence from the UK Medicines and Healthcare Products Regulatory Agency. The CPRD collects de-identified data from a network of GP practices therefore no written informed consent was obtained. The interpretation and conclusions contained in this study are those of the authors alone.
: Not applicable.
: The authors declare that they have no competing of interests.