What the authors showed is that by training standard machine learning algorithms (random forests, logistic regression, gradient boosting, and a shallow neural net) on readily-available signals from the medical record (e.g., prior diagnoses), you can increase the c-statistic from 0.728 to 0.764. These machine learning techniques are well-suited to the data set and the empirical evaluation is strong, so this work should really stand on its own without trying to brand it AI.
There is some very high quality work on artificial intelligence in medicine being done today. Google Brain published a validation study of a convolutional net to diagnose diabetic retinopathy in December, and Stanford published similar work but applied to skin cancer. NIPS 2016 had an excellent Machine Learning for Health workshop with several works-in-progress: http://www.nipsml4hc.ws/