Without additional context the only difference could be "brought to the hospital" could mean from a different place by car for example. "brought into the hospital" may be that the patient was dropped off or waiting outside but couldn't get in by them self and so they were brought in. There is also the possibility that we can assume that if a patient was "brought to the hospital" that they would have natural gone in as well, and that the other sentence was only being more specific in its description.
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