Center for Evidence-Based Medicine;
Henan University;
Kaifeng 475000;
China.;
Center for Evidence-Based Medicine;
Henan University;
Kaifeng 475000;
China.;
Center for Evidence-Based Medicine;
Henan University;
Kaifeng 475000;
China.;
Center for Evidence-Based Medicine;
Henan University;
Kaifeng 475000;
China.;