research topic

It looks to me like you have two different problems that you want to look at...PTSD and substance abuse assessments. I think you need to narrow it down a little more. What about looking at reasons for noncompliance with substance abuse assessments? Then as part of your project you could work on a solution to the problem. Is it that nurses are uncomfortable doing the assessments? Is the tool use confusing or difficult to use? Maybe to a literature search and see what kind of information you can find.

I agree- starting with a lit review often helps me to organize my priorities, see what is currently being discussed, and can often bring up a new idea or question.

I agree - the literature review will be helpful as it will tell you what's already been researched so you don't waste your time and perhaps guide you to a specific area that needs to be further understood. One idea might be to go to the limitations sections of relevant articles and see if you can address the limitation in your study.

Good luck! I'm working on narrowing down my topic for my MSN project, and it's hard! LOL I'm still in the "which idea shall I pick" phase, haven't even made it to the "narrowing down of the topic" phase yet.