Perhaps you should try some spelling variations:
ratings risk » patients risk
direct cost » direct costs, indirect cost, indirect costs
wang liang » wang yang
liang ying » liang liying, huang ying, zhang ying
life cost » life costs, life lost, life case
among men » among women
jie cost » die cost, time cost, diet cost

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: wang liang ying ((((jie cost) OR (life cost))) OR (direct cost)) ratings risk among men ;~.
• Adding a wildcard symbol may retrieve word variants: wang liang ying ((((jie cost) or (life cost))) or (direct cost)) ratings risk among men ;*.