This Scale can be thought of as a couple of different things:

• A dominant 9th Arpeggio
• A Major Pentatonic scale with the 6th swapped for a b7

Let’s look at it side by side with the Major Pentatonic

Major Pent.   –  1 2 3 5 6

Dom Pent.     –  1 2 3 5 b7

This one note makes a huge difference, the b7 is an important chord tone when playing over a dominant sound (Which most blues songs are)

You will hear this a lot in more jazz influenced Blues as well as fusion blues. Sometimes you’ll even hear it in the Texas blues. Check out John Coltrane, Robben Ford, and Albert Collins.