In English, "anyway" is sometimes used to change the subject of conversation.
Anyway, how are you?
Is the corresponding German word "sowieso"?
Sowieso, wie geht's dir?
Are there other options?
My favourite words for changing the subject:
Wie dem auch sei, wie geht es dir eigentlich/überhaupt? (Literally: However that might be)
The überhaupt can be used when you want to add the nuance that it just occured to you that you should have asked this earlier. My Sprachgefühl tells me that eigentlich (or überhaupt)is what really effects the topic change, like saying "this is what's important now".
Then there is:
Unabhängig davon; wie geht es dir eigentlich/überhaupt? (Literally: Independently of that)
The subsentence stress has to be on da. I think it is pretty neutral, conveying no criticism of the old topic.
(Hier,) mal was anderes, wie geht es dir eigentlich/überhaupt? (Literally: Now for something different)
The hier can be used as some sort of interjection to "soften the blow", but it's not mandatory and it can also be used in combination with the other suggestions. The version with the hier is somewhat colloquial.
Another one would be:
(Naja,) wie/was auch immer, wie geht es dir eigentlich/überhaupt? (Literally: Whatever)
This one is especially good for "rescuing" yourself if you mixed up facts and want to close the discussion until you have looked them up again (which might be never). But: this can sound sloppy, only recommended for colloquial use.
If you want something really short, you could also use:
Naja! Wie geht es dir eigentlich?
This one is a bit difficult because much depends on tone when using naja. This might sound a bit critical of whatever was said before if not said in a light, friendly tone, with stress on the ja. (Don't say nah-ja. That might lead to more discussion.)
Generally, some interjection (ja, hm, ach ja, naja, mm, hier,...) in combination with eigentlich or überhaupt should be enough, the longer versions are optional.
The other possibilities mentioned in the other answers do not really sound natural to me (native speaker). But that might depend on region, profession ...
I think one of them can be salvaged:
Nebenbei gesprochen, wie geht es dir eigentlich? (Literally: Said by the way)
Although this does not really change a subject, but rather sidetracks it temporarily (like by the way maybe) with the intention of coming back to the original topic afterwards.
Sowieso is completely wrong in this context. It just does not make any sense.
I'd translate this to:
Wie auch immer; [Hauptsatz]
Wie auch immer; wie geht es Dir?
sowieso seems wrong to me. A somehow literal translation would be
jedenfalls, which sounds wrong to me either.
No, I wouldn't use "Sowieso". While the sentence might be understood, the word is commonly used to emphasize the meaning of the rest of the sentence:
Das ist sowieso klar. So können wir das sowieso nicht machen.
I would use something like
Nebenbei, wie geht es Dir?
Or, to emphasize that one has forgotten to ask about it:
Wie geht es dir überhaupt? Überhaupt, wie geht es dir eigentlich?