Heart failure hospitalization prediction in remote patient management systems
ABSTRACT Healthcare systems are shifting from patient care in hospitals to monitored care at home. It is expected to improve the quality of care without exploding the costs. Remote patient management (RPM) systems offer a great potential in monitoring patients with chronic diseases, like heart failure or diabetes. Patient modeling in RPM systems opens opportunities in two broad directions: personalizing information services, and alerting medical personnel about the changing conditions of a patient. In this study we focus on heart failure hospitalization (HFH) prediction, which is a particular problem of patient modeling for alerting. We formulate a short term HFH prediction problem and show how to address it with a data mining approach. We emphasize challenges related to the heterogeneity, different types and periodicity of the data available in RPM systems. We present an experimental study on HFH prediction using, which results lay a foundation for further studies and implementation of alerting and personalization services in RPM systems.
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ABSTRACT: In this paper we describe an Heart Failure analysis Dashboard that, combined with a handy device for the automatic acquisition of a set of patient's clinical parameters, allows to support telemonitoring functions. The Dashboard's intelligent core is a Computer Decision Support System designed to assist the clinical decision of non-specialist caring personnel, and it is based on three functional parts: Diagnosis, Prognosis, and Follow-up management. Four Artificial Intelligence-based techniques are compared for providing diagnosis function: a Neural Network, a Support Vector Machine, a Classification Tree and a Fuzzy Expert System whose rules are produced by a Genetic Algorithm. State of the art algorithms are used to support a score-based prognosis function. The patient's Follow-up is used to refine the diagnosis.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2012; 2012:2210-3.
Heart Failure Hospitalization Prediction in
Remote Patient Management Systems
M. Pechenizkiy, E. Vasilyeva, I.ˇZliobait˙ e
Department of Computer Science
P.O. Box 513, 5600 MB, TU Eindhoven
A. Tesanovic, G. Manev
Philips Research Laboratories
HTC 5, 5656 AE Eindhoven
Healthcare systems are shifting from patient care in hos-
pitals to monitored care at home. It is expected to improve
the quality of care without exploding the costs. Remote pa-
tient management (RPM) systems offer a great potential in
monitoring patients with chronic diseases, like heart failure
or diabetes. Patient modeling in RPM systems opens oppor-
tunities in two broad directions: personalizing information
services, and alerting medical personnel about the chang-
ing conditions of a patient. In this study we focus on heart
failure hospitalization (HFH) prediction, which is a partic-
ular problem of patient modeling for alerting. We formulate
a short term HFH prediction problem and show how to ad-
dress it with a data mining approach. We emphasize chal-
lenges related to the heterogeneity, different types and peri-
odicity of the data available in RPM systems. We present an
experimental study on HFH prediction using, which results
lay a foundation for further studies and implementation of
alerting and personalization services in RPM systems.
Chronic diseases are the leading cause of death and
healthcare costs in the developed countries. Healthcare sys-
tems are shifting from patient care in hospitals to monitored
care at home . Adequate patient monitoring, instruction,
using Remote Patient Management (RPM) systems. RPM
systems are expected to assist in normalization of patient
condition and preventing re-hospitalization. Figure 1 shows
an example of an RPM system.
Recently, a possible architecture of the next generation
personalized RPM systems was introduced . The study
presented a general process of knowledge discovery from
RPM data. It identifies potentially useful features and pat-
terns, which are used for patient modeling and constructing
the adaptation rules.
In this study we formulate and address the problem of
hospitalization prediction, which is a part of patient mod-
eling. In broader terms hospitalization means severe wors-
ening of a patient condition. Informally we distinguish five
horizons of prediction: next step, short, medium, long term
and life-long prediction. Life-long prediction is out of the
scope of patient modeling. Next step horizon means a cou-
ple of hours, short term means a couple of weeks, medium
means months and long term means years. Different pre-
diction horizons relate to different possible actions.
We focus on a short term hospitalization prediction,
which is the most relevant in terms of extraordinary med-
ical actions to prevent the upcoming worsening (Section 2).
We study a case of repeated heart failure. Repeated means
that the patients have already had a heart failure and are be-
ing monitored. Previously, decision rules that should trigger
an alarm in case of possible Heart Failure Hospitalization
(HFH) have been designed manually based on the domain
expertise. We employ a data mining approach (Section 3)
for patient modeling, which utilizes information across dif-
ferent data sources. Our study, preliminary result of which
were discussed in , shows that it is possible to learn pre-
dictive models, that outperform the trigger rules, authored
by the experts, in terms of their accuracy (Section 4).
2Background and problem definition
This section presents RPM setting and the problem of
HFH prediction in its context.
2.1Remote Patient Management systems
Existing commercial RPM systems typically provide an
end-to-end infrastructure that connects patients at home
with medical professionals at their institutions (Figure 1).
workspaces. The first is for the doctors to monitor condi-
tions of the patients and adjust therapy. The second is for
the patients to post the symptoms and exchange information
with the responding medical professional. Some systems
allow the delivery of personalized documents to the patients
such as information about the disease, healthy lifestyle
recommendations or suggestions on a diet.
Home monitored patients generate various types of data
recorded by different means (Table 1). Data collected dur-
ing RPM process contains typically both objective (vital
signs) and subjective (questionnaires) measurements about
the condition of a patient. The vital sign measurements
are collected using sensors and transferred to the monitor-
ing and management server via application hosting device.
The signs to be monitored depend on the chronic disease
in question. Weight and blood pressure is typically moni-
tored for heart failure (HF) patients, glucose and weight –
for diabetes patients. Subjective measurements, collected
from the patients via questionnaires, include symptoms and
quality of life (QoL) scores. The questionnaires can be pre-
sented to patients directly via an application hosting device
or a feedback device, such as a TV.
Based on the indicated deviations from the normal val-
ues, a medical professional can adjust the treatment plan
including medications, nutrition and physical activity.
2.2Predicting HF hospitalization
eases. It causes high mortality and implies high treatment
costs. Early and accurate detection of HF situations makes
it possible for RPM systems to intervene with appropriate
education, instructions, and medications. Timely interven-
tion is expected to improve the condition of a patient as well
as to reduce the future treatment costs.
Figure 1. Architecture of an RPM system.
Table 1. Types of home patient data.
Data clases Collected via
Face to face meeting
at a medical
Face to face meeting
at a medical
An RPM system at a
-An RPM system at
a patient’s home, but
also can be collected:
- Via a telephone
contact by a medical
- Via face to face
regular checkups at
the protocol of
care and can
- Daily (RPM)
- Few months
(face to face
Face to face meeting
at a medical
- Via a telephone
contact by a medical
- Via face to face
Few weeks to
Patients with chronic HF have phases of clinical stability
interrupted by episodes of worsening. In such case, a previ-
ously stable chronic HF patient shows worsening symptoms
that the body cannot compensate any more. Worsening of
HF may lead or not lead to hospitalization of the patient.
Although, both are important, we focus on the problem of
heart failure hospitalization (HFH) prediction as the case of
prior importance. HF patients might also be hospitalized
due to non HF reasons. In this study we consider a hospital-
ization as HFH, if the first diagnosis was ‘heart failure’ or
the primary admission reason was worsening HF.
We consider a short term prediction of worsening. In
this study we define short term as two weeks. Short period
is particularly relevant for HFH prediction in terms of pos-
sible follow up actions, like an extraordinary appointment
with a doctor. If the period is too long, like several months,
then the prediction output is not relevant in terms of actions.
Figure 2. Predicting within the next 14 days.
HFH is expected for HF patients anyway. If the period is
too short, like a day or so, then it is too late to take an action
other than to hospitalize the patient anyway.
We formulate the problem of HFH prediction in the fol-
lowing way. For a given patient the task is to predict if HF
hospitalization will occur within the next 14 days. Assume
today is day ti. The predictive features are formed using
the patient data collected up and including day ti. Positive
prediction means that HFH is likely to occur in the period
from day ti+1to ti+14, which we call the hospitalization
The prediction is casted every day. Every day new mea-
surements become available and the predictive features are
updated. Every day the hospitalization window moves one
day further. Based on the daily prediction output an alarm is
raised if deemed necessary. The timeline of the data avail-
ability is illustrated in Figure 2. The data is used by medical
experts or an automated classifier for the prediction and the
following decision making.
The patient data has different periodicity. Medical his-
tory data (H features) is recorded at the time of enrolment
(t0). It includes information related to previous hospital
admissions, existence of valve diseases, evidence of coro-
nary diseases, arrhythmias, devices implanted and more. A
record may contain dozens of fields, typically it is recorded
only once.Quality of life symptoms (S features) are
recorded approximately every month, during a phone con-
tact (MCj). The patients are also asked to report additional
data such as disease and non-disease medication or medica-
tion change; a number of visits or contacts in the last month
at home, by phone, at the office, at the clinic. The vital signs
(Dfeatures), suchasweightorbloodpressure, aremeasured
on a daily basis using sensors.
3Data mining approach to HFH prediction
HFP prediction can be addressed as a time-series predic-
tion or a classification task. We focus on the classification
In order to learn a classifier we need labeled training data
with both positive and negative instances, each represented
by a set of the features, which are expected to be predictive.
The process of forming a training set is illustrated in Fig-
ure 3. Given a large number of H, S and D features as well
defining the labels
Figure 3. Training set formation process.
as different periodicity they are measured, a feature set con-
struction is the major challenge. In this section we discuss
how to identify potentially useful features and how to form
positive and negative instances.
3.1Feature extraction and construction
HFH may be explained by a number of factors [1,3,6].
Demographics and baseline measurements are considered
to be important for a long term prediction of the health sta-
tus. Daily, weekly or monthly measurements are expected
to have a short-term prognosis value. From the medical do-
main it is known that different symptoms and signs may
cause and possibly predict HFH. However, recent studies
focused mainly on daily measurements such as weight dy-
namics for predicting HFH.
In this study we assemble the primary set of predictive
ter understanding of what features may potentially describe
To gather this information we employ event-pattern analysis
and exploration of time-series data.
For the event-pattern analysis we use dot charts. Dot
charts give an insight into frequency of and precedence
of events starting from the beginning of the clinical study.
They also assist in finding the outliers or errors, for exam-
ple, a monthly contact via phone or a measurement that took
place while patient was in the hospital.
Dot charts also help to notice potentially interesting pat-
terns that in turn help to identify and construct potentially
useful features, for instance, weight dynamics. Moreover, it
can be clearly observed that a number of patients are mea-
suring themselves during the working days, but not during
weekends. That suggests that the use and impact of RPM
system is dependent on a lifestyle of the patients. Another
strong relation was observed between the frequency of mea-
suring and a contact with medical professionals. For in-
stance, if a patient does not measure herself for some time,
a clinical visit or a monthly contact triggers the patient to
restart measuring. This suggests that communication in-
creases patient motivation to use the system.
Exploration of time series data shows how the values of
daily measurements or symptoms change over time. It also
1We keep the description of the feature set construction at a high level
for proprietary reasons. This is in line with our goal to give a broad per-
spective and suggest potentially relevant problem formulations.
Figure 4. Weight dynamics of three patients.
indicates how these measurements correlate with certain
events, such as hospitalization based on particular symp-
toms. An example of weight timeseries for three patients is
shown in Figure 4. Here relations between a rapid weight
increase, hospitalization and change of a prominent symp-
tom for HF (ankle swelling) can be observed.
Databases are typically noisy and our case is not an ex-
ception. We apply explorative statistical data analysis, out-
lier detection, data cleaning approaches and handling the
missing values to filter relevant data.
3.2Positive and negative instances
Having a collection of relevant data and knowledge
about potentially relevant features we can form training in-
stances. This is not trivial due to different periodicity at
which the measurements are obtained.
To form the positive training instances for a patient we
first find which day HFH has actually occurred (th). Then
we take a period of 14 days backwards [th−14,th) to com-
Figure 5 illustrates the timeline. It should be noticed that
data for computing these features may go back further than
this two week window. A feature itself might code dy-
namics of the measurement or exceeding some predefined
threshold. An example of such feature could be, how many
times the weight exceeded 100 kg in the last three days. The
value of the feature for day th−14will be computed using
the data from [th−16,th−14]. The medical history (H) and
symptom (S) features are computed based on the last avail-
able data. Further discussion related to the feature space
construction is given in the next section.
A similar approach is used to construct the negative in-
stances. The trick is how to choose a reference time th. We
set thto be an average between the time of two consecutive
Figure 5. Forming one training instance.
monthly contacts, given that no HFH happened in between.
This way we expect to smoothen the effect of how fresh the
symptom information is.
It should be noted that for each patient present in the
training database several negative instances and potentially
more than one positive instance can be constructed. Exact
numbers depend on the duration of the observed period for
the corresponding patient and on how many times she has
been hospitalized during it.
We performed a quantitative evaluation of our approach
on an extract from the TEN-HMS database  contain-
ing information about 426 patients with cardiovascular dis-
eases, of whom 143 patients (112 alive and 31 dead) were
HF patients home telemonitored during the period of two
years and had records at least for 50 days period. 43 pa-
tients had at least one HFH.
4.1Experimental set up
Our experiments had two major goals: to assess the per-
formance of different classification methods and to explore
the predictive power of different types of features. We eval-
uated the results against nine rules, which were established
based on domain expertise and are in use in current RPM
systems. The rules themselves cannot be disclosed.
The experimental set up consisted of two major steps.
First we tested a number of classifiers: support vector ma-
chines (SVM), decision trees (J48), and rule-based learners
(JRip) . We experimented with different parameter set-
tings on the training data. Then, the selected best classifiers
were compared against the triggering rules on the test data.
For each combination of parameters we experimented
with different feature subsets: only symptom features (S),
symptom and daily measurement features (S + D), symp-
tom and medical history features (S+H), and their union
(S+D+H). Additionally, we tried some of these subsets and
finally an exhaustive search (FS) for the best feature sub-
set (S+D+H+FS). We fixed the best parameters for each
classification technique on the training data using ten fold
cross-validation. In each category we left only those com-
binations, which were statistically significantly better than
Figure 6. HFH prediction accuracies for dif-
ferent parameterizations and feature sets on
the training set (cross-validated).
others according to paired t-test with respect to Youden in-
dex (YI). The test regards true positive rate (TPR) and false
positive rate (FPR) as equally important, YI = TPR - FPR.
on the test dataset. To form the test set we held out 29 pa-
tients. For each test patient we formed test instances for all
monitoring days, the scenario was presented in Figure 2. At
day tiwe aimed to predict whether HFH will occurs within
the next 14 days [ti+1,ti+14]. In total there were 220 pos-
itive test instances and 9605 negative instances, obtained
from 29 patients, which formed the test set.
We present validation and test results. In Figure 6 the
performance of different parameterizations and feature sub-
sets on the training set is presented (cross-validated). The
results are plotted against the true positive and false posi-
tive rates. Note, that the performance of an ideal classifier
would correspond to TPR = 1 and FPR = 0, the top left cor-
ner. The diagonal represents random predictions.
The results suggest that combining the daily measure-
ment (D) and symptom (S) features improves the perfor-
mance of classification techniques, as compared to only S,
the points are closer to the top left corner. Adding the med-
ical history features (H) in many cases improves even fur-
ther. SVM shows the good results in terms of FPR, while
JRip classifier is better in terms of TPR. J48 has shown the
Figure 7. HFH prediction accuracies of the
classifiers vs. the expert rules on the test set.
best FPR, but overall it was slightly behind the other two
classifiers in terms of Youden index, which combines both
FPR and TPR.
The results on the test dataset are plotted in Figure 7 and
complemented with Table 2. When interpreting the results,
it needs to be taken into account, that the number of cor-
rect classifications can be higher than the actual number of
hospitalizations. It is due to the problem formulation and
the experimental set up. The label is considered to be true
if HFH occurred within 14 days. Thus it is also true for
the next prediction, but now within 13 days and so on. In
this setup one hospitalization generates up to 14 positive
instances. Therefore, besides TPR we also report the hospi-
talization prediction rate (HR) that is how many HFHs have
been predicted out of the total number of actual HFHs.
The key result of the experimental study is the following:
classification approaches perform much better than individ-
ual predefined expert-rules (Rule1 – Rule8). The results are
The relative performance of different classifiers is compara-
ble to their performance on the training data.
4.3Challenges with symptom features
The results suggest that symptom features S play a key
role in the performance of classifiers. We finalize the case
study with discussing challenges related to S features.
Classifiers showed rather high false positive rate, which
Table 2. Prediction accuracies on the test set.
Classification model TPR FPR YIndex HRate
can be attributed to the impact of S features. Indeed, S fea-
tures by their own allow to predict HFH in many cases.
From the domain perspective, symptoms are the early warn-
ing signals of worsening, but typically over a longer hori-
zon. S features normally allow to say that there is a high
chance of the hospitalization within a month, but not within
a short 14 days period. Thus, if classification is based pri-
marily on S features the model can generate a large number
of false alarms in a row. To reduce FPR, additional han-
dling mechanisms need to be introduced, which is a subject
of further investigation.
Periodicity of S features requires separate attention. The
direct measurement of S features may become outdated, due
to relatively long intervals between monthly contacts. As a
result, a particular symptom might have changed but not yet
be recorded. In addition, there might be completely or par-
tially missing values due to the organizational or technical
reasons. In such cases, predictive modeling of the symp-
tom features might improve the performance of HFH pre-
diction. We experimented with predicting two most promi-
nent symptoms, breathlessness and swelling of ankles. The
results were promising and opened a future research direc-
We presented a generic approach for modeling patient
state for personalized information and alerting of worsen-
ing. Within the scope of modeling for alerting, we formu-
lated a problem of a short term hospitalization prediction.
we presented a data mining approach to predict heart fail-
ure hospitalization, with a particular focus of training set
construction. An experimental study with the data from a
real clinical trial demonstrated the benefits of our approach
as compared to expert based prediction. It also opened
prospects for further research.
The immediate follow up steps of the work include im-
proving HFH prediction via handling different periodicity
of the data. Another step would be to switch from crisp to
probabilistic prediction within the prediction horizon, out-
putting hospitalization probability for each day. In addition,
we plan to make use of the educational data, motivational
messages and other feedback provided to the patient by an
RPM system or medical personnel, to obtain reliable and
up-to-date information about the symptoms, and to make
our prediction approach context-aware.
EU HeartCycle and KWR MIP projects.
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