Full Text of Machine Learning Expert Suchi Saria’s talk titled “Better Medicine through Machine Learning” at TEDxBoston conference.
Listen to the MP3 Audio here:
Suchi Saria – Associate Professor of Machine Learning and Healthcare at Johns Hopkins University
Let me introduce you to Mrs. Manny. She came to the emergency room. She is fifty two years old. She came to the emergency room with a foot sore. Doctors investigated her foot sore and she ended up staying there in the hospital for 22 days.
Here’s what happened.
When she came to the emergency room for a foot sore, they inspected her, they saw no real reason for medical concern but they wanted to monitor in case her foot sore was infected. So, they put her in the general ward.
On day three, she starts developing symptoms of what looks like mild pneumonia. They give her the usual treatment of antibiotics and all’s good but then her condition starts to worsen.
On day six, she develops what’s called ‘tachycardia’ that means in medical speak, her heart rhythm has accelerated dramatically. She then has trouble breathing.
On day seven, she experiences septic shock; that means her body is in crisis. Incidentally, mortality in shock is one in two. Now, it’s only at this point that the doctors get really concerned and they transfer her to the intensive care unit.
ICUs are the units where the most critically ill patients get cared for. Here, they give her every possible treatment to stabilize her but her condition only worsens.
First, her kidneys start to fail. Then her lungs fail and on day 22, she dies.
Mrs. Manny did receive the right set of treatments. The problem is, she received them only too late. What Mrs. Manny experienced was an infection that turned into sepsis.
Let me tell you a little bit about what sepsis is. Sepsis occurs when infection releases chemicals in your blood to tackle the infection. So, your body releases chemicals to fight the infection. Now, this chemical can trigger a negative inflammatory response. When this inflammation triggers this negative inflammatory response, what it can then do is cause a cascade of changes, leading your organs to fail, leading to death.
Sepsis is the 11th leading cause of death, more than breast cancer and prostate cancer combined. Turns out, sepsis is preventable if treated early, okay?
So, then what’s the catch? Doctors find it very hard to recognize sepsis. In fact, a Harvard study shows with 93 leading academic experts that when they were given several cases of patients with and without sepsis, they couldn’t agree.
Two years ago, my nephew, he was admitted to the best Hospital in India and he died of sepsis. My family was devastated.
I’m a machine learning expert and what I do is study ways in which we can use large messy datasets to enable intelligent decision-making. So, natural question for me was, could machine learning have helped? Could machine learning have helped Mrs. Manny and my nephew?
So, this led to a massive effort with my colleagues at Hopkins to design what we call ‘the targeted real-time early warning system’ or TREWS based on machine learning. I’ll give you a sneak peek into what TREWS is and how we’re using it to tackle sepsis.
Let me take a step back and tell you a little bit about what machine learning is and what’s AI.
Artificial intelligence is a field of study where we teach computers how to learn. Okay? Just like you teach your kids. Machine learning is one way of doing this, by designing code or programs that teach computers stuff over time by interacting with the environment or watching. Okay?
So, I’m going to show you a video of some robots learning how to walk. I find it funny how it shudders. So, you’re probably now thinking this is hopeless.
Well, so the question is, how can we teach robots or machines how to walk. Intuitively, you can think of it as designing a game. The goal of the game is for the computer or the robot to learn how to walk for as long as possible without following. Okay?
So, to do this, first we have to design, write down the goal in a language the computer understands. For this, we’ll use math. Okay, so now you’re wondering, well how do we write the goal of walking without falling as long as possible in math?
Well, that’s often hard for different tasks but you can think of it as writing down a formula and what this formula does is it scores.
So, in the case of walking, it’ll score every move the robot makes. If the move it makes helps the robot walk, it gets a high score. If the move that the robot speaking makes the robot unstable, it gets a low score.
And now the robot’s goal is to experiment with the sequence of moves in order to be able to maximize its score. So, how does it know which moves to try? Right?
Well, there are two strategies for doing it. First, it learns by interacting with the environment, okay? So, here the robot will just make a guess. It guesses, it makes a move. If the move gets a high score, that’s positive feedback and the robot builds on it. Okay?
The second strategy is by watching other robots. In other words, the robot finds data from past robots that are similar to this robot. It watches what moves that robot did when it was in very similar positions and now it emulates or replicates those moves. Okay? So, those are the two strategies.
So, now I’m going to show you a video of robot learning how to walk using the strategy I just described. Okay, so in the beginning it’s going to look hopeless but I promise you it gets better. And just to be clear, this the skeleton of the robot and so this is not a human animator going there and just moving or animating this video. This is really the robot, the algorithm choosing which moves to make by moving the joints of the skeleton that you’re seeing and you can see it’s already getting better.
Now, suddenly the robot’s able to walk and run for a lot longer than it was doing, right? So, essentially the basic principle is as follows.
You figure out a game that the computer can play, you write it down using a language it understands and then we train it to optimize the score, right?
This is how we teach cars how to drive, computers how to play the game of go, an Alexa to understand say your preference of coconut water.
So, let’s go back in our case, the problem of sepsis. So, the goal here is to identify sepsis as quickly as possible, right? And for this, TREWS learns by watching.
In other words, using data from past patients. This avoids the need for TREWS to have to experiment on new patients, right? So, to do that, what are the pieces TREWS needs to do?
So, one big change that has happened in medicine that’s interesting to note is, in the past five years, the introduction of electronic health records in EHRs, every single measurement, every single lab test that is ever done when you walk into the clinic or you’re in the hospital gets collected.
TREWS analyzes this data from thousands of patients to identify subtle signs and symptoms that appear in patients with sepsis than those without, okay? But that’s not alone. What TREWS also needs to do is to figure out how to think about every signal in the context of every other signal.