Does Interrupted count as Used?

If I shot an opponent with Choking Gas and then cast Wastrel's Worry on them, would WW be canceled if the opponent tried to cast a spell?

What about if I cast Wastrel's Worry and then Mark of Subversion?

[COLOR=Olive]Choking Gas[/COLOR] (Preparation) For 12 seconds, your arrows deal 1..7 more damage and spread Choking Gas on impact. Choking Gas interrupts enemies attempting to cast spells.

[COLOR=Green]Mark of Subversion[/COLOR] (Hex Spell) For 4..9 seconds, the next time target foe casts a spell on an ally, the spell fails and you steal 10..76 Health from that foe.
[COLOR=Magenta]
Wastrel's Worry[/COLOR] (Hex Spell) After 3 seconds, target foe takes 8..53 damage. Wastrel's Worry ends prematurely if that foe uses a skill.

I'm pretty sure that wastrels is only dispelled when the spell is cast (after the casting animation). So if you interrupt the skill before it is complete, wastrels will remain. They will also have lost the energy cost from the skill they used, in addition to being interrupted.