Help understanding とわかった

Question

I was reading the article linked and included below and came across the following sentence

ＮＨＫが調べると、病院で「エコノミークラス症候群」だとわかった人がこの女性以外に１９人いました。

Could someone please explain the grammar and/or meaning of とわかった?

As for my thoughts, I assume that the sentence is trying to convey (without regard to how it flows in English)

When the NHK looked into it, there were 19 people not including the woman (mentioned previously) who were afflicted with Economy Class Syndrome.

I originally thought とわかった was と分かった and for some reason beyond my current understanding, と was used instead of か making the sentence mean "...people who know what Economy Class Syndrome is". I discounted this as possible since it didn't seem relevant to the context and I think that such a meaning requires 知る anyway.

Also, as I wrote my translation, I began wondering why で was used with 病院 if it is indicating a location of state rather than a location of action. Perhaps my translation is off.

Any help is appreciated.

http://www3.nhk.or.jp/news/easy/k10010488191000/k10010488191000.html

地震が続いている熊本県で１８日、車の中に泊まっていた５１歳の女性が病院で亡くなりました。この女性は「エコノミークラス症候群」になっていました。

車の中など狭い場所で長い時間体を動かさないと、足の血が流れにくくなって血の塊ができます。その塊が肺の血管に詰まると亡くなることもあります。これを「エコノミークラス症候群」と呼んでいます。

ＮＨＫが調べると、病院で「エコノミークラス症候群」だとわかった人がこの女性以外に１９人いました。この人たちは車の中にずっといて胸が痛くなったりしたと言っています。この中の２人は重体です。 ...

Answer 1

I originally thought とわかった was と分かった

It is, but it might better help to translate it as identified here, rather than understood. That sentence means:

The people whom they identified at the hospital as (having) "Economy Class Syndrome" numbered 19 besides/in addition to this woman.