Acknowledgements
I thank my supervisor Dr. Hong-Wu Wen, who has provided me with valuable guidance in every stage of the writing of this thesis. Without his enlightening instructions, I could not have completed this work. I also thank all doctors from the Perking University First Hospital, who participated in this study.
Ethics
We, the authors, declare that our study follows the principles of the Declaration of Helsinki.
Disclosure statement
No potential conflict of interest was reported by the authors.