Concepts: S-H Chuang, C-H Chang; design: S-H Chuang, C-H Chang; definition of intellectual content: S-H Chuang, C-H Chang; literature search: S-H Chuang, C-H Chang; clinical studies: S-H Chuang, C-H Chang; experimental studies: S-H Chuang, C-H Chang; data acquisition: S-H Chuang, C-H Chang; data analysis: S-H Chuang, C-H Chang; statistical analysis: S-H Chuang, C-H Chang; manuscript preparation: S-H Chuang; manuscript editing: C-H Chang; manuscript review: S-H Chuang, C-H Chang; guarantor: C-H Chang.