Sustained Impact of Electronic Alerts on Rate of
Prophylaxis Against Venous Thromboembolism
Patrick Emanuel Beeler1, Nils Kucher2, Jürg Blaser1
1 Research Center for Medical Informatics, Research and Education, University Hospital
2 Venous Thromboembolism Consult Service, Clinics for Angiology & Cardiology,
University Hospital Bern, Switzerland
Keywords (MeSH Terms):
- Clinical Decision Support Systems
- Computerized Medical Records Systems
- Venous Thromboembolism/prevention & control
- Reminder Systems
Running title: Sustained Impact of eAlerts
Correspondence: Prof. Dr. Jürg Blaser
Direktion Forschung und Lehre
Sonneggstr. 6, D5
Phone. +41 44 255 3618
Fax: +41 44 634 5503
Advanced electronic alerts (eAlerts) and computerized physician order entry
(CPOE) increase adequate thromboprophylaxis orders among hospitalized medical
patients. It remains unclear whether eAlerts maintain their efficacy over time, after
withdrawal of continuing medical education (CME) on eAlerts and on thromboprophylaxis
indications from the study staff.
We analyzed 5317 hospital cases from the University Hospital Zurich during 2006-
2009: 1854 cases from a medical ward with eAlerts (intervention group) and 3463 cases
from a surgical ward without eAlerts (control group). In the intervention group, an eAlert
with hospital-specific VTE prevention guidelines was issued in the electronic patient chart
6 h after admission if no pharmacological or mechanical thromboprophylaxis had been
ordered. Data were analyzed for three phases: pre-implementation (phase 1), eAlert
implementation with CME (phase 2), and post-implementation without CME (phase 3).
The rates of thromboprophylaxis in the intervention group were 43.4% in phase 1
and 66.7% in phase 2 (p<0.001), and increased further to 73.6% in phase 3 (p=0.011).
Early thromboprophylaxis orders within 12 hours after admission were more often placed
in phase 2 and 3 as compared to phase 1 (67.1% vs. 52.1%, p<0.001). In the surgical
control group, the thromboprophylaxis rates in the three phases were 88.6%, 90.7%,
Advanced eAlerts may provide sustained efficacy over time, with stable rates of
thromboprophylaxis orders among hospitalized medical patients.
Deep vein thrombosis (DVT) and pulmonary embolism (PE) together are referred
to as venous thromboembolism (VTE) (1). The DVT attack rate (incidence of first and
recurrent DVT) has been estimated for the United States and the European Union at
128/100,000 person-years (2) and 148/100,000 person-years (3), respectively.
Approximately one quarter of all VTE events are hospital-related and at least 70% of the
VTE-associated deaths occur as a consequence of a hospital-acquired VTE (3, 4). The
case fatality rate of PE approximates 7-11% (5, 6).
Appropriate use of prophylaxis to prevent VTE is an important strategy for
improving safety among hospitalized patients (7, 8). A recent meta-analysis found
significant reductions in any PE (relative risk 0.43) and fatal PE (relative risk 0.38) due to
thromboprophylaxis without a significant increase in major bleeding complications (9).
The American College of Chest Physicians (ACCP) has established evidence-
based guidelines for the prevention of VTE, including pharmacologic treatment with
anticoagulants and mechanical prophylaxis (e.g. compression stockings) (10).
Nevertheless, many patients at risk do not receive prophylaxis, as evidenced by three
large studies (11-13). The ACCP suggests the use of various strategies for increasing
thromboprophylaxis adherence, explicitly including the use of computer decision support
systems (CDSS). Some studies investigated computerized reminders of prophylaxis and
found substantially higher thromboprophylaxis rates due to electronic alerts (eAlert) (14-
16). However, lack of physician compliance with electronically generated suggestions is a
well-known problem called ‘alert fatigue’ or ‘overriding’ (17).
Research on VTE prevention has been a focus at the University Hospital Zurich in
recent years in the context of an ongoing quality assurance program which also covered
multicenter studies (18, 19). In 2007, an advanced eAlert module was developed and
implemented into the clinical information system (KISIM, Cistec AG, Zurich, Switzerland)
of a medical ward. An eAlert was issued in the electronic chart six hours after the patient
was admitted to the ward if no pharmacologic or mechanical prophylaxis had been
ordered. All healthcare professionals involved in the patient care were reminded by a
highlighted alert button to consider thromboprophylaxis, but only the physician was
enabled to respond to the eAlert. When the physician clicked on the eAlert button, an
information screen displayed hospital-specific guidelines on VTE prevention in medical
Physician compliance with the VTE eAlerts was evaluated in a pilot study (16).
During this period, continuing medical education (CME) on prevention of VTE in
hospitalized patients and on the eAlert system was provided to the staff physicians of the
medical ward. The rate of appropriate prophylaxis during this pilot study averaged 76%,
as compared to a much lower rate of 44% observed in a cross-sectional 1-day survey
prior to the implementation of computerized physician order entry (CPOE) (16, 18). The
prospective pilot study focused on physicians’ compliance. It did not consider data on the
prophylaxis rate in patients treated in the same medical ward immediately before or after
the study period, and no data were available on patients treated in other wards during the
identical period, in the absence of eAlerts.
The purpose of the present analysis was to comparatively assess the sustainability
of the eAlert system over time.
Materials and methods
Two wards of the University Hospital of Zurich, Switzerland, introduced CPOE in
2006, i.e. a medical ward (intervention group) and a surgical ward (control group). Then,
CPOE was limited to these wards, including 22 beds in medicine and 23 beds in surgery,
respectively. The remaining wards in medicine (164 beds) and surgery (239 beds) were
not considered since they introduced CPOE not before 2009.
In the medical intervention ward, but not in the surgical ward, an eAlert was
displayed in the electronic chart of each patient who did not receive a pharmacological or
mechanical thromboprophylaxis order within six hours after admission (16). Prophylaxis
guidelines including a VTE risk score are displayed by default when the physician
acknowledges the eAlert button.
All patients admitted to the study wards from April 2006 to December 2009 were
enrolled if they stayed for at least 24 hours in these wards and (i) either entered these
wards directly or (ii) entered these wards via the emergency department; i.e. in-patients
transferred from other wards were excluded. The electronic charts of the included patients
were searched for orders of pharmacological and mechanical prophylaxis. All orders of
prophylaxis were considered for the time period from admission to discharge or transfer of
the patient to another ward.
We analyzed 5317 hospital cases during 2006-2009: 1854 cases from the medical
intervention ward with eAlerts and 3463 cases from the surgical ward without eAlerts. The
overall study period included 45 months: (a) pre-implementation phase 1, 4/2006-8/2007,
(b) eAlerts implementation phase 2, 9/2007-12/2008, and (c) post-implementation
phase 3, 1/2009-12/2009. The eAlert module was implemented in the intervention ward at
the beginning of phase 2 and included monitoring of the appropriateness of the ordered
VTE prophylaxes (16). The eAlerts remained in operation in the intervention group also
during phase 3. Only during phase 2 was specific CME on indications for prophylaxis
provided to the physicians of the intervention group. No specific CME was offered to the
physicians of the control group. This quality improvement initiative study was approved by
the local ethics committee and patient consent was waived.
The rate of prophylaxis was defined as the percentage of patients with at least one
order for VTE prophylaxis during their stay in the admitting ward. Combined prophylaxis
was defined as orders of both pharmacologic and mechanical prophylaxes.
Clinical outcome at discharge was assessed for all three phases by searching the
patient charts for diagnoses of PE and DVT (I26.0, I26.9, I82.8, I82.9; International
Classification of Diseases [ICD-10], World Health Organization, Geneva, Switzerland). All
VTE diagnoses were independently adjudicated by two physicians, classifying them into
pre-existing events and hospital-acquired complications. Hospital-acquired VTE events
were considered if they were symptomatic and objectively confirmed by an imaging test.