Modern and massively parallel computing platforms can process humongous amounts of data in real time to obtain actionable insights for effective clinical decision making. In this blog, I discuss an emerging Big Data platform called Apache Spark and its application to remote real-time healthcare monitoring using data from medical devices and wearable sensors. The goal is to provide effective remote care for an increasingly aging population as well as public health surveillance.
The Apache Spark Framework
Apache Spark has emerged during the last couple of years as an innovative platform for Big Data and in-memory cluster computing capable of running programs up to 100x faster than traditional Hadoop MapReduce. Apache Spark is written in Scala, a functional programming language (see my previous post titled Navigating in Scala land). Spark also offers a Java and a Python APIs. The Scala API allows developers to interact with Spark by using very concise and expressive Scala code.
The Spark stack also includes the following integrated tools:
- Spark SQL which allows relational queries expressed in SQL, HiveQL, or Scala to be executed using Spark through a data abstraction called SchemaRDD. Supported data sources include Parquet files (a columnar storage format for Hadoop), JSON datasets, or data stored in Apache Hive.
- Spark Streaming which enables fault-tolerant stream processing of live data streams. Data can be ingested from many sources like Kafka, Flume, Twitter, ZeroMQ or plain old TCP sockets. The ingested data can be directly processed with Spark built-in Machine Learning algorithms.
- MLlib (Machine Learning Library) provides a library of practical Machine Learning algorithms including support vector machines (SVM), logistic regression, decision trees, naive Bayes, and k-means clustering.
- GraphX which provides graph-parallel computation for graph-analytics application like social networks.
Apache Spark can also play nicely with other frameworks within the Hadoop ecosystem. For example, it can run standalone or on a Hadoop 2's YARN cluster manager, on Amazon EC2 or a Mesos cluster manager. Spark can also read data from HFDS, HBase, Cassandra or any other Hadoop data source. Other noteworthy integrations include:
- SparkR, an R package allowing the use of Spark from R, a very popular open source software environment for statistical computing with more that 5800 packages including Machine Learning packages; and
- H2O-Sparkling which provides an integration with the H2O platform through in-memory sharing with Tachyon, a memory-centric distributed file system for data sharing across cluster frameworks. This allows Spark applications to leverage advanced distributed Machine Learning algorithms supported by the H2O platform like emerging Deep Learning algorithms.
Wearable Sensors for Remote Healthcare Monitoring
Three factors are contributing to the availability of massive amounts of clinical data: the rising adoption of EHRs by providers thanks in part to the Meaningful Use incentive program; the increasing use of medical devices including wearable sensors used by patients outside of healthcare facilities; and medical knowledge (for example in the form of medical research literature).
One promising area in Healthcare Informatics where Big Data architectures like the one provided by Apache Spark can make a difference is in applications using data from wearable health monitoring sensors for anomaly detection, care alerting, diagnosis, care planning, and prediction. For example, anomaly detection can be performed at scale using the k-means clustering machine learning algorithm in Spark.
These sensors and devices are part of a larger trend called the "Internet of Things". They enable new capabilities such as remote health monitoring for personalized medicine and chronic care management for an increasingly aging population as well as public health surveillance for outbreaks and epidemics.
Wearable sensors can collect vital signs data like weight, temperature, blood pressure (BP), heart rate (HR), blood glucose (BG), respiratory rate (RR), electrocardiogram (ECG), oxygen saturation (SpO2), and Photoplethysmography (PPG). Spark Streaming can be used to perform real-time stream processing on sensors data and the data can be processed and analyzed using the Machine Learning algorithms available in MLlib and the other integrated frameworks like R and H2O. What makes Spark particularly suitable for this type of applications is that sensor data meet the Big Data criteria of volume, velocity, and variety.
Researchers predict that internet use on mobile phones will increase 20-fold in Africa in the next five years. The number of mobile subscriptions in sub-Saharan Africa is expected to reach 635 millions by the end of this year. This unprecedented level of connectivity (fueled in part by the historical lack of land line infrastructure) provides opportunities for effective public health surveillance and disease management in the developing world.
Apache Spark is the type of open source computing infrastructure that is needed for distributed, scalable, and real-time healthcare analytics for reducing healthcare costs and improving outcomes.