Propose: To present DeepCOVID-Fuse, a deep learning fusion model to predict risk levels in patients with confirmed coronavirus disease 2019 (COVID-19) and to evaluate the performance of pre-trained fusion models on full or partial combination of chest x-ray (CXRs) or chest radiograph and clinical variables. Materials and Methods: The initial CXRs, clinical variables and outcomes (i.e., mortality, intubation, hospital length of stay, ICU admission) were collected from February 2020 to April 2020 with reverse-transcription polymerase chain reaction (RT-PCR) test results as the reference standard. The risk level was determined by the outcome. The fusion model was trained on 1657 patients (Age: 58.30 +/- 17.74; Female: 807) and validated on 428 patients (56.41 +/- 17.03; 190) from Northwestern Memorial HealthCare system and was tested on 439 patients (56.51 +/- 17.78; 205) from a single holdout hospital. Performance of pre-trained fusion models on full or partial modalities were compared on the test set using the DeLong test for the area under the receiver operating characteristic curve (AUC) and the McNemar test for accuracy, precision, recall and F1. Results: The accuracy of DeepCOVID-Fuse trained on CXRs and clinical variables is 0.658, with an AUC of 0.842, which significantly outperformed (p < 0.05) models trained only on CXRs with an accuracy of 0.621 and AUC of 0.807 and only on clinical variables with an accuracy of 0.440 and AUC of 0.502. The pre-trained fusion model with only CXRs as input increases accuracy to 0.632 and AUC to 0.813 and with only clinical variables as input increases accuracy to 0.539 and AUC to 0.733. Conclusion: The fusion model learns better feature representations across different modalities during training and achieves good outcome predictions even when only some of the modalities are used in testing.
