How to filter for dead player item entities?

When a player dies they drop all their items on the ground. The problem is that it's not real dropping so the items don't have a "Thrower". I thought I could filter by "Age" but it has differences to the players last death time of up to 50 ticks (results from the tests I did, could be higher) which is way to high to loop through. I mean I could loop through all the ticks but I have the feeling that this would be a hugh perfomance issue. Is there other way to do it?