CHAPTER 2: Ontario’s Telehealth system: A novel syndromic surveillance system
1Infectious Disease Epidemiology Unit, London School of Hygiene and Tropical
The US Centers for Disease Control and Prevention define syndromic surveillance as
“an investigational approach where health department staff, assisted by automated data
acquisition and generation of statistical alerts, monitor disease indicators in real-time or
near real-time to detect outbreaks of disease earlier than would otherwise be possible
with traditional public health methods.”
Syndromic surveillance initially came into prominence as a bioterrorist surveillance
methodology primarily following the events of September 11th, where a rapidly evolving
emergency situation required regular and timely access to epidemiologic information to
foresee and plan for the allocation and use of limited and stressed resources. It has
subsequently evolved into a sub-discipline of epidemiologic surveillance beyond the
exclusive scope of bioterrorism preparedness[2-4] to include, among others, pandemic
preparedness[5,6], West Nile surveillance[7,8], and as a potential tool to enhance
routine surveillance systems commonly used within the field of public health.
A significant benefit of syndromic surveillance systems is that they characteristically rely
on the use of pre-existing datasets, thereby foregoing the challenges associated with the
development and implementation of a data-collection infrastructure (including buy-in,
funding, and adoption), as well as increasing communication within the public health
system and between acute care and public health.
Canada, and many other countries, have access to data streams that are electronically
captured in a timely manner that could theoretically be used for the purpose of
syndromic surveillance. These include, but are not limited to emergency/A&E
data[10,11], absenteeism data, emergency calls, ambulance dispatches,
patient transfers, over the counter drug sales, billing data and telephone
In Ontario, Canada, it is evident from the post-SARS literature that the Ontario public
health system was, and arguably remains, burdened by many of the shortcomings
consistently seen with routine public health surveillance systems. Part of the failure of
the public health system during SARS was attributed to a lack of timely communication
between implicated stakeholders. The problems encompassed within the definition of
“lack of timely communication” cannot be attributed exclusively to the lack of an
infrastructure to share data in a timely fashion; however, this was one of the main
problems confronting the individuals and institutions involved in the control of the SARS
The Initial Report of the Ontario Expert Panel on SARS and Infectious Disease Control,
published as a response to the SARS outbreak in Ontario, Canada, stated that the
aforementioned failures in public health surge capacity could be potentially addressed by
“hav[ing] a well-developed system for real-time data sharing and reporting, and for the
rapid dissemination of surveillance information.” In particular, it mentioned the
potential to “broaden the information collection capacity of Telehealth as a syndromic
Following the lead established by the UK’s NHS Direct Syndromic Surveillance system,
we are retrospectively evaluating the value of Ontario’s Telehealth’s health helpline as a
syndromic surveillance system. To date, there have been no published descriptions of
Telehealth. This article endeavours to address this lacuna by providing an overview of
Telehealth, Ontario’s nursing telephone helpline, including how data are collected,
stored, and how the data may be evaluated to determine this data source’s usefulness
as a in an enhanced awareness surveillance system.
Description of Telehealth
The Ontario Telehealth Telephone Helpline (henceforth referred to as “Telehealth”) was
implemented in Ontario in 2001. It was initiated as a pilot study, which included the
Greater Toronto area (416 and 905 calling areas), as well as the Northern area of
Ontario (705 calling area). The Northern Pilot was subsequently evaluated, “suggest[ing]
that teletriage may have decreased visits to emergency departments relative to patient
intent,” one of the goals of Telehealth being to “lead to more appropriate use of
The program was expanded province-wide at the end of 2001, and has been
administered by Clinidata, a private contractor hired by the Ontario Ministry of Health
and Long-Term Care. The helpline is available 24 hours a day, 7 days a week, including
holidays, at no cost to the caller. The calls are answered by registered nurses who
are required to have multiple years of clinical experience prior to their involvement with
Telehealth. Although calls are primarily answered in both official languages (English and
French), the system has the capability of responding to calls in 110 different languages
within 60 seconds (with the help of translators in a three-way calling setup).
Calls are handled by four calling centres that use identical decision rules (algorithms)
and store all call information into one centralized data repository (unlike the UK system
that relies on local call centres with proprietary databases). The calls are usually
approximately 10-minutes, patient based, and are directed by trained nurses who use an
electronic clinical support system that can be used to provide either clinical guidelines
(approved by a panel of clinicians), health information, care information, and a health
This Telehealth evaluation project was approved by a REB, as well as meeting Ontario
Personal Health Information Protection Act (PHIPA) and Ontario Municipal Freedom of
Information and Protection of Privacy Act (MFIPPA) requirements. The anonymised data
were provided by the Ontario Ministry of Health and Long-Term Care as well as with
Clinidata, the private company contracted out to administer Telehealth. The agreement
resulted in a record of all calls spanning June 2004-June 2006 (25 months).
Who Calls Telehealth, When and Why?
Between June 2004 and June 2006, a total of over 2 million calls were made, averaging
approximately 2700 calls daily, slightly lower than the numbers published elsewhere. Of
calls where the caller’s sex was recorded, 64.1% of calls were made by females, which
can be explained in large part by the fact that mothers tend to be the primary caregiver
for children and frequently call on their behalf. Calls were categorized into one of three
categories: Health information (11.3% of all calls); Service referral (4.9% of all calls);
The volume of calls was not the same across all months. The highest call volume was
recorded in January 2005 (97,896 calls), followed by March 2005 (95,097 calls). The
highest call volume in the 2005-2006 year was in March 2006, with 92,527 calls. As a
general rule, call volumes increased during influenza season (December-March), and
were lower in the non-influenza months (Figure 1), which is similar to Telehealth call
patterns reported elsewhere, as well as call patterns for other systems.
The largest proportion of calls was made during weekends – 15.2% of calls were made
on Sundays, and 15.9% of calls were made on Saturdays, when doctors’ offices are
routinely closed. The smallest proportion of calls were made on Thursdays (13.7%)
(Table 1). Of the calls where time of day was recorded (97.8% of all calls), nearly half of
calls (47.5%) were made in the late afternoon and evening (16:00-23:59), when
physicians’ offices are closed, followed by the daytime (08:00-15:59) (37.8%). The
remaining calls were made between 24:00 and 07:59.
The dataset provided to the project did not include information about whether the caller
called for him/herself or for someone else. However, the age recorded in each record is
the age of the person the call was made for. For example, if a mother called for her son,
the age of the son, not the age of the mother, was recorded. The majority of calls were
made for/by individuals aged 18-64 years of age (52.3%). Nearly 18 percent of calls
were made for children aged 0-4 years, followed by calls for/by children aged 5-17 years
(10. 5%). The smallest percentage of calls were made by/for individuals aged 65 years
and above. Approximately 13 percent of calls did not have an age specified.
Syndromic Surveillance-Specific Data
For the purpose of the evaluation of Telehealth’s usefulness as a syndromic surveillance
system, the main interest is in symptom calls, which are triaged to a clinical guideline-
driven nurse helpline. These calls represent a call volume of approximately 1.7 million
calls, or approximately 84% of all calls made to Telehealth during the time period under
study. These calls are of most interest to us as the other call types (health information
and service referral) do not provide symptom information, the basic variable required for
Description of Algorithms
When a symptom call is made, the call nurse follows through a decision tree, based on
the algorithm that the nurses assesses as best describing the caller’s initial
complaint. At the end of a symptom call, once the decision tree has been followed to
its conclusion, a call is assigned one of 11 dispositions. These dispositions include:
- Information call (calls initially coded as symptom calls, but where no care is
The frequency of disposition type is available in Table 2. The most commonly recorded
disposition was “physician referral,” (41.9%). However, this category includes two types
of physician referral – referral within 24 hours and referral within 72 hours if no
improvement. The data as provided do not differentiate between the two. The next most
commonly recorded disposition was “self care” (31.1%), whereby the caller/patient is to
remain at home without seeking further medical condition, unless an important change in
While there are 480 algorithms that a Telehealth nurse can chose from, there are some
algorithms selected more frequently than others. Table 3 provides an overview of the ten
most frequently assigned algorithms. Although the most common age group of callers
was the 18-64 year age group, the top three most commonly assigned algorithms were
pediatric after hours algorithms and, overall, 5 of the top 10 were pediatric. Therefore,
although the majority of calls were not pediatric ones, the most commonly reported
symptoms were pediatric vomiting, cough and fever – common childhood symptoms.
This cannot be explained by a greater diversity of algorithms across adult age groups,
relative to pediatric ones, as approximately 47% of all 440 algorithms were pediatric
ones, with the remaining 53% being adult-specific or all age group algorithms.
For the purpose of using Telehealth as a syndromic surveillance tool, the different
algorithms were categorized against prodrome categories by an emergency medicine
physician with experience in this area. The prodromal categories include respiratory
upper, respiratory lower, influenza-like illness, dermatological infectious – vesicular,
dermatological infectious – not vesicular, neurological infectious, asthma,
gastroenteristies. These categories were developed by the RODS-based Ontario
Syndromic Surveillance Pilot Project and were used and validated within an emergency-
department (A&E) setting, with a primary focus on outbreak detection of public health
The project’s next steps will include classifying all algorithms to one of the
aforementioned prodromal categories, quantitatively comparing Telehealth data with
laboratory data and emergency department (A&E) visits, and, using the CDC Framework
for evaluating public health surveillance systems for early detection of outbreaks,
retrospectively determining whether the Telehealth system could be successful as an
early-warning system. More details on these steps are described elsewhere.
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