I. Introduction
The rate of generated health data has grown exponentially in recent years due to the expansion of electronic medical records, wearable technologies, and health tracking applications. As a result, healthcare providers are investing their resources into building platforms that can leverage this data to improve patient health. The trend in healthcare is shifting from cure to prevention. Hospitals and healthcare systems house useful repositories of big data (like patient records, test reports, medical images, etc.) that can be leveraged to cut the costs of healthcare, to improve reliability and efficiency, and to provide more effective treatments to patients [19]. Applying data science methods to health data has been proven to assist with such advances. Some success stories include using wearable technologies to monitor and prevent health problems, advancing pharmaceutical research to help find cures for diseases, and reducing hospital readmissions to cut healthcare costs, among many others [2, 7, 20]. Leveraging patient-patient similarity is the backbone behind many of these models. However, patients do not always comply with appointment schedules, and occasionally measurements are missed during routine checkups. These events leave gaps in patient records, which hinder machine learning methods that take these values into consideration when making predictions.