Does refridgeration prolong the shelf life of a buttercream cupcake

I've had cupcakes sit out on the counter for about 4 days.I don't think refridgerating them will make them last longer..maybe a day or so...Now if they sat longer and the butter maybe began to go rancid....but there is so much icing sugar I doubt it!!

I've had them last at least 5 days at room temperature, in an airtight container. In fact, mine seem to get better as they age, because the buttercream makes the cake more moist the longer it sits. I've never noticed any signs of rancidity. In fact, I've wondered just how long they really could go...but they're usually all eaten before I can find out!