1 Department of Nursing, Liaocheng Vocational & Technical College, Liaocheng 252000, PR China.
2 Department of Cardiology, The Second People's Hospital of Liaocheng, Liaocheng 252000, PR China.
3 Department of General Practice, Liaocheng People(')s Hospital and Clinical School of Taishan Medical University, Liaocheng 252000, PR China. Electronic address: linyan_yu88@126.com.