For each patient we considered only the prediction of novel diseases, discarding the re-diagnosis of a disease
It seems to me you need a longer time series (patient with 3,4,5 years of medical history) to be able to predict a future disease state. And I don't believe I saw that in the article (I admit I read through it quickly).
If it turns out, this is just identifying undiagnosed diseases, I wonder if this research will have any legal ramifications.