I am using the Changes module to track IT change requests and its workflow from Request initiation to Go live with multiple stages in between. I want to find out how much time was spent in each stage of the workflow. This is similar to the time spent in tickets module. But i cant find a equivalent for the changes module. 

If i could get the activities details through an API that would be the best, but dont find an API that would get me the activities details for a change.

Any Ideas ?