What is 'Actuarial Trend'

Ok please help me, as I have many gaps in my background. I hear a lot of talk about health actuarial trend. I think the way I understand it is this:
Yeara cost
Yearb cost

Trend = Yearb cost/Year a cost - 1 (*100). Is this right please (and really hope there is more to it otherwise I think I would have to leave the profession). Thanks


What is 'Actuarial Trend'