You'd have to check specifically if the
SubscriptionApproved and the
SubscriptionApprovalHash have specific values in them. For instance if the use is confirming the subscription and you have two events:
You can check to see if the
SubscriptionApproved = true in the before event, if it does not, then do something. Or you can check in the
After event if you'd like. Just depends on what you want to do.