Capture the index of Constraints

For example.  Say I have a drop down that displays names of cities.  If a user selects the 5th city in the drop down, is there a way for me to capture that index in the _ValueChanged event?  What I'm trying to do is update a .txt file with both the .Caption and the .Data values of the constraint so I need to reference them like;

 

Item.Constraints(5).Caption
Item.Constraints(5).Data

 

where (5) is the index of the selected drop down.