Thinking about it some more, if a clinical domain can be related to any issue, cause, etc., why not just put all of those items into 1 table with a field to distinguish to what category (issue, cause, action etc.) the item belongs? This will simplify the form since you can have each list box reference the same table and just filter each based on the category.
tblItems
-pkItemID primary key, autonumber
-fkCDID foreign key to Clinical domain table
-txtItem
-fkCategoryID foreign key to tblCategory