Why does Tomato Sauce (ketchup) require refrigeration but Barbecue sauce (like Worcestershire sauce) does not? We have two types of sauce we put on our sausages. Tomato Sauce (Australian - ketchup equivalent) and Barbecue Sauce (Australian - mix of ketchup and Worcestershire sauce). The Tomato sauce indicates it needs refrigeration but the Barbecue sauce (made by the same company) does not say this. 

My question is Why does Tomato Sauce (ketchup) require refrigeration but Barbecue sauce (like Worcestershire  sauce) does not?
You don't actually have to refrigerate ketchup. Once it's opened it's good for a month or so with no appreciable change. After that the flavour and colour starts to degrade, but it's still safe to eat.

Worcestershire sauce is fermented for more than a year before it's bottled, so it will change at a much slower rate than an acidic, but unfermented sauce like ketchup. Still, it's only good for a few years after it's opened.