Ten out of 17 studies (58.8%) provided combined development with internal and/or external validation, with the best reported predictive performance belonging to a model developed in Greece with 67 participants and an AUC of 0.97 based on patients’ gender, presence of hypertension and diabetes, fever, shortness of breath, serum glucose, AST, LDH, CRP and fibrinogen [261].We present detailed characteristics of the studies in the supplemental material Table 4. The gene discussed is CRP; the disease is diabetes mellitus.