How much does being out of CM for years hurt hiring chances?

I have been looking for full time CM position after being out of the field for 15 years. My past background in CM is extensive, but was from 1985-1995. After a few years out of nursing, I returned to part time work in home care and with a mental health agency 4 years ago. Now, I need a full time position. I am not certified (back then it was not such an important qualification - now I see it is used to differentiate nurses) I do have a Masters in Health Services Administration. I would be happy to take the exam, but have to meet the verified experience requirement to take it which I can't get from old employers for insurance privacy reasons.

How difficult will it be to get back in to CM with the employment gap? I got an 80% on the CCM practice exam, so I know things in theory and law have not changed much since 1995. I still have concerns the gap may be a problem, but don't know what to do about it - just keep applying until I find one? I want to move forward in my career, not start over. Any suggestions from hiring folks would be welcome.

Annette L.