Machine Learning in Medicine: It Has Arrived, Let’s
Embrace it
Scott M Pappada, PhD1,2,3,4
1Department of Anesthesiology, The University of
Toledo College of Medicine, Toledo, OH 43614, USA
2Department of Bioengineering, The University of
Toledo, Toledo, OH 43606, USA
3Department of Electrical Engineering and Computer
Science, The University of Toledo, Toledo, OH 43606, USA
4Department of Anesthesiology, The Ohio State
University Wexner Medical Center, Columbus, OH 43210, USA.
It is safe to say that machine learning and artificial intelligence (AI)
in medicine has arrived and it is time for the healthcare community to
embrace it. There has been significant recent growth in the adoption and
use of machine learning in medicine, and researchers and healthcare
professionals are trending towards leveraging it for multiple purposes
including, for example, in the prediction of patient outcomes which are
being used to drive decision-making surrounding patient interventions
and care. An excellent recent demonstration of the adoption of machine
learning in medicine is the recent manuscript by Ayers et al[1],
whose team developed an ensemble machine learning-based model to predict
patient survival one year following orthotopic heart transplantation
(OHT). The primary purpose of this machine learning approach was outcome
prediction (i.e. , likelihood of patient survival one year after
organ transplantation), however, as the authors allude to, this modeling
approach also has significant implications in terms of improving
clinical decision making, patient counseling, and ultimately organ
allocation. This particular modeling approach significantly outperforms
other established OHT algorithms created by Nilsson et al. in 2015 and
Weiss et al in 2011[2, 3]. The improved accuracy of the ensemble
model developed by Ayers and colleagues with respect to these prior
algorithms can perhaps be tied to the fact that its predictions are
based on the output of hundreds of models, where each model’s training
data is generated by employing varying degrees of data re-sampling of
the comprehensive United Network for Organ
Sharing (UNOS) database which is growing in its use for “Big Data”
applications by the healthcare community[4]. Ayers and colleagues
therefore have effectively produced hundreds of models each of which
were developed using diverse training data sets which will improve the
capability of the models (400 in this case) to evaluate different
relationships across the dataset. This effectively contributes to
improvements in the prediction of patient survival one year following
transplantation. The use of machine learning-based approaches, such as
this ensemble modeling approach, provides a mechanism to evaluate a
diverse set of variables (N=525) and factors far beyond traditional
measures which drive organ allocation, that include but are not limited
to the medical need of the recipient, compatibility of blood type, and
physical proximity between recipient and the donor. Machine
learning-based approaches are uniquely suited to evaluate hundreds of
preoperative factors and variables that provides a more personalized
organ allocation recommendation.
When designed and utilized appropriately, machine learning-based
software and technologies will provide tremendous value across many
clinical settings. Let’s investigate the potential implications of
incorporating the machine learning-based approach proposed by Ayers et
al.[1] into clinical practice and its potential impact on patient
care given future adoption and advancement of the models. As discussed,
these machine learning algorithms provide potential to significantly
improve not only organ allocation but a means to optimize patient
longevity following transplantation. Ayers and colleagues provide an
envisioned use case where the model is utilized iteratively each time an
organ becomes available across several candidates to identify which
patient has the highest likelihood of reaching the one-year survival
milestone following transplantation. This data-driven process provides a
more personalized recommendation of patient survivability and has the
potential to evaluate numerous clinical, psychological, and behavioral
measures that significantly surpass existing conventional selection
criteria. With machine learning-based approaches and the continued
growth in patient data availability, many other data sources, factors,
and variables can be investigated and incorporated into other models
that may arise and are adopted in the future. Increased availability of
salient patient data will result in a significant improvement in model
performance and accuracy over time. An example of improved patient data
availability would be data collected via ambulatory patient monitoring,
both post-operatively and post hospital admission. Ambulatory patient
monitoring is becoming more commonplace and routine especially with the
increased adoption of telemedicine[5, 6]. Wearable devices such as
the FitBit® which are used across the general
population are now beginning to be widely investigated for use across
patient populations.[7, 8] These wearable devices offer a unique
potential to document factors that can be incorporated as model
inputs/predictors to improve model-generated recommendations for organ
allocation, patient counseling, and many other aspects[9-11]. In
this future use case, healthcare providers can keep track of important
factors such as patient activity[12], emotional status, and sleep
quality[13, 14] both preoperatively (for organ allocation purposes)
and postoperatively (to improve patient compliance and ultimately
survivability). The adoption of machine learning coupled with current
standard organ allocation criteria provides a unique potential to not
only optimize organ allocation but to provide better insight into
patient care requirements after a successful transplantation. As more of
these technologies are utilized across larger patient groups, the
additional data collected can be utilized in a dynamic sense to
continually enhance the real-time performance of existing models and to
further contribute to improvements in model accuracy. This same approach
could also be applicable in patient survival models where the additional
data collected during each patient encounter will continuously enhance
model performance. Healthcare providers will be able to evaluate
predictions and recommend changes to patient treatment, lifestyle, or
behaviors that may improve upon survivability. Adding additional machine
learning algorithms such as unsupervised techniques may also allude to
patterns amongst specific patient cohorts and support the identification
of various factors that may contribute to positive or negative patient
outcomes. This will effectively allow healthcare providers to deliver
more focused and personalized patient care.
The increased adoption of advanced patient monitoring technologies
coupled with the expansion and advancement of electronic medical records
(EMR) continues to generate significant sets of data across numerous
patient care settings. Along with this considerable growth in electronic
data, the cognitive and physical burden of healthcare providers (HCPs)
to interpret these patient data sources also continues to grow. To
ensure optimal patient care, providers must adapt to this continuously
evolving space and evaluate the output of these new technologies and
data sources when arriving at their patient care and treatment
decisions. The persistent growth of medical technologies and electronic
healthcare data has shepherded medicine into the era of “Big
Data”[15]. While the need to interpret and apply knowledge from
these various patient data sources can sometimes be overwhelming for
HCPs[16], the availability of significant datasets provides a
critical foundation for future use by the medical research community to
assist in developing innovative healthcare technology solutions through
the use of machine learning and AI. Consistent with this trend, the
United States Food and Drug Administration (FDA) realizes that machine
learning and AI hold tremendous promise for the future of medicine, and
as a result are developing a new regulatory framework to promote
innovation in this space and to support the use of AI-based
technologies[17]. Digital health tools which use machine learning
and AI have significant potential to improve the abilities of HCPs in
the diagnosis, treatment, decision making, and even healthcare
administration. These data driven tools, algorithms, and techniques
offers the unique potential for medical care to become truly
personalized at the patient level. There are countless applications for
data science in healthcare. One application includes the diagnosis of
key medical conditions and disease states including but not limited to
cancer[18], sepsis/septic shock[19, 20], and developmental
disabilities such as autism spectrum disorder[21, 22]. Machine
learning has also been applied to drive clinical decision making and to
provide decision support in a diverse set of clinical settings and
specialties including but not limited to neurosurgery[23],
cardiovascular medicine/cardiac surgery[24, 25],
endocrinology[26-28], radiology[29], and critical
care[30-32]. It has also been leveraged for time series prediction
of specific patient vital signs[33, 34] or even therapeutic
setpoints[28, 31, 35]. Similarly, algorithms and modeling approaches
have also been applied to prediction of patient outcomes including
mortality[36, 37], length of stay in the hospital[38, 39] or
intensive care unit[40, 41], readmission[42-44], and countless
others.
In medicine today, optimal patient care, including the delivery of
treatment to improve patient outcomes, relies on the rigorous monitoring
of a large quantity of patient data which often can be distributed
across various information systems. The ability to properly identify,
track, and interpret each related data source can be time consuming,
labor intensive, and will result in cognitive overload for even the most
experienced of healthcare professionals. Therefore, machine learning and
AI in medicine will definitely play a significant role in positively
impacting patient safety and care due to its ability to better manage
and interpret “big-data” sources. As has been shown, when software and
technologies implementing machine learning are designed appropriately,
they are able to significantly reduce experienced cognitive load[45]
of healthcare providers, thereby, providing a better working environment
and potentially leading to reductions in provider burnout[46-48]
which is a major issue facing our healthcare workforce today.
Furthermore, staff and resources are often constrained in healthcare
environments and useful data, trends, and/or correlations between
variables often go unnoticed because healthcare professionals do not
have the time or capacity to properly evaluate all incoming data. This
is where software tools and technologies that implement machine learning
and AI can be of tremendous value. While many factors and variables are
documented in patient medical records, they aren’t necessarily
incorporated into the decision-making process. Data science can be
leveraged to identify subtle patterns or factors that are of specific
interest and allow for a more effective prediction of patient outcomes
of interest. It is now possible to find patterns and trends amongst
seemingly unrelated data sources which may not even be part of routine
clinical evaluations and/or assessment practices. While machine learning
has considerable potential, it should be stressed that it alone cannot
eliminate uncertainty in clinical care. It can, however, provide a means
to rapidly evaluate a multitude of variables and factors that would take
even an experienced provider a significant amount of time to process and
draw conclusions. This is one of its greatest advantages. The “Big Data
Revolution” has arrived and machine learning and AI in medicine is here
to stay. Software and patient monitoring technologies implementing
sophisticated models and algorithms will soon be commonplace across
healthcare settings. While being a promoter of machine learning and AI
in healthcare, it is also important to note that they will never replace
a seasoned and experienced healthcare provider. They will, however,
provide healthcare providers an extremely valuable tool to guide and
augment their expert clinical decision-making. Personalized medicine has
been a long-standing goal of the healthcare community and with machine
learning and AI now being continually incorporated into clinical
settings and practice, this technology is well on the pathway to make a
considerable impact to greatly improve patient care in the near future.