In my experience CMDB is almost universally the Configuration Management Database (that's the definition in ITIL), not Change Management Database. Of course change management is closely associated with configuration and I would expect it to be integrated but the abbreviation ought to be used in the normally acceptable way.
Also, to answer the question, CMDB systems have to be integrated into service management, performance and other systems. Once things start going wrong with systems with abstracted services then, if you've no idea where things are running or what performance levels are being achieved by the umpteen layers of abstracted levels of service in a modern IT infrastructure, you are stumped. Some simple things can be dealt with through simple capacity planning approaches, but they can't deal with the more complex issues where real application behaviour touches the metal.
There is, incidentally, no such thing as a comprehensive general purpose CMDB and it remains, to my mind, the most difficult technical problem in designing software to manage IT services.