Implementation of the montreal heat response plan during the 2010 heat wave.
Price, Karine ; Perron, Stephane ; King, Norman 等
Extreme heat episodes result in significant morbidity, especially
in northern latitudes or areas influenced by more temperate climates.
(1,2) A recent meta-analysis showed that both environmental factors,
such as the absence of air conditioning, and population risk factors,
such as having cardiovascular or psychiatric co-morbidities, increase
the probability of heat-related deaths. (3) Following the European heat
wave of 2003, 15,000 excess deaths were reported in 12 European
countries during the first week of August and approximately 24,000
during the second week. (4,5) This event prompted many countries to
initiate or reinforce heat health watch warning systems to avoid high
levels of excess mortality. (6,7) To counter the effect of extreme heat,
the Montreal public health department has developed a heat response plan
in collaboration with the regional and local public health network and
municipal partners. This plan has been in effect since 2004. Its
development was prompted by the large increase in mortality following
the 2003 heat wave in Europe. Although preventive measures following
Environment Canada's heat warnings have been issued to the
population since 1994 and a communication campaign was initiated in
2002, the Montreal health department heat plan was undertaken by public
health authorities to describe actions under different alert levels with
local partners. Indeed, although the heat response plan is addressed to
the public health network, public health actions are coordinated with
municipal and civil security partners. Health and weather surveillance
is an important component of the plan, both for immediate intervention
and for updating the plan. These indicators serve as a basis for
determination of different levels of action during the summer period.
The main objective of the Montreal heat response plan (MHRP) is to
reduce heat-related mortality and morbidity. In order to attain this
objective, the plan must clearly identify and coordinate actions to be
undertaken under different alert levels by partners at the regional
public health and municipal level. The MHRP also serves as a guide for
the health and social services network (e.g., hospitals or health and
social services centres) to develop their own local heat plan for the
people they serve. The following paper presents a brief overview of the
Montreal heat response plan and its implementation in Montreal during
the July 2010 heat wave, which was the first time the Intervention level
was reached. (8) Results of the surveillance activities and ensuing
actions are also presented.
The Montreal heat plan
Target Population and Setting
The MHRP covers the Island of Montreal. It comprises five levels
which define different actions to be taken, namely the Normal level,
Seasonal watch, Active watch, Alert level and Intervention level (Table
1). The attainment of these levels is determined through surveillance of
weather and health indicators. The weather threshold upon which
emergency interventions take place was determined following analysis of
all-cause mortality during different heat wave episodes spanning a
20-year period from 1984 to 2004. (9) The weather threshold was based on
a 60% increase in all-cause mortality. This threshold corresponds to a
weighted average maximum temperature of [greater than or equal to]
33[degrees]C over 3 days and a weighted average minimum temperature of
[greater than or equal to] 20[degrees]C over 3 days. (10) The
surveillance of health and weather indicators is ensured by the Montreal
public health surveillance team on a daily basis as part of an existing
surveillance system developed by the Montreal public health department.
(11) Mortality data are accessed daily from hospital statistics. Health
indicators include total mortality (death occurring at home or in the
community, long-term health care and hospital mortality), number of
pre-hospital emergency transports (Urgences-sante), calls to the health
information line (Info-Sante) and hospital admissions. The surveillance
system automatically brings attention to these indicators when they
increase above expected baseline values. However, it is important to
note that the increases in health indicators are also evaluated
subjectively using information from the field. At the Active watch
level, following a heat warning by Environment Canada(forecast of
temperatures [greater than or equal to] 30[degrees]C and Humidex
[greater than or equal to] 40), the system automatically transmits a
heat warning to various partners. At the Alert level, following a
forecast reaching or exceeding the aforementioned threshold
temperatures, daily conference calls are scheduled between the public
health network and partners at the municipal and civil security level.
The onset of emergency interventions (Intervention level) takes place
when these predetermined temperature levels have been attained or are
forecast to be attained and health indicators are above normal levels.
Public Health Intervention During the Extreme Heat Event of July
2010
In the beginning of July 2010, Montreal experienced a heat wave
that lasted 5 days, with a mean maximum temperature above 33[degrees]C,
while minimum temperatures stayed above 20[degrees]C for 9 days. During
the heat wave, temperature as well as health indicators were tracked
daily by the Montreal public health surveillance team. In addition,
further information on pre-hospital emergency transport and deaths
occurring in the community were obtained on a daily basis through
Urgences-sante. Following the onset of the Intervention level, many
actions were performed by municipal, regional and local public health
partners. These actions are wide-ranging (mass media communication,
involvement of local health departments in order to identify vulnerable
individuals, opening of air-conditioned shelters, extension of pool
opening hours, etc.). (8) Interventions also involve hospitals and
long-term care, pre-hospital emergency care, boroughs and cities in the
island of Montreal, police and fire departments (see Table 1 for more
details).
[FIGURE 1 OMITTED]
Following the heat wave, there was an excess in daily observed
mortality from all causes, particularly in the community. As part of our
surveillance efforts, the Director of public health conducted a chart
review of all people deceased from July 5 to July 11, 2010, a period
that spanned the heat wave. Individual evaluation of 304 records was
performed, according to contribution of heat and place of death
(community, long-term health care facility, hospitals). The chart review
was not part of the actions initially described in the heat plan, but
was prompted by the excess mortality and was part of the Director of
public health's surveillance mandate.
OUTCOME
Health indicators during the heat wave
Between July 5 and July 11, 2010, there was a noted increase in the
number of calls to Info-Sante regarding oppressive heat (Figure 1A), and
a clear increase in pre-hospital emergency transports and total and
community deaths (Figure 1B and 1C). However, emergency room visits did
not increase during this period. Pre-hospital transportation and
Info-Sante calls were the first indicators to vary with increases from
baseline detected as early as July 5. Deaths in the community and total
deaths increased only as of July 7. Other indicators, such as deaths in
hospitals, deaths in the emergency wards and deaths in long-term care,
did not show any clear patterns. (8)
Chart review
As presented in Table 2, of the 304 deaths from all causes in
Montreal residents, 106 were probably or possibly heat-related. In order
to quantify the contribution of heat, the medical team at the Montreal
public health department developed a medical chart extraction form (see
Supplemental Appendix A), based on information in the literature
provided in case-control studies. (12,13) From this chart extraction
form, the mortality cases were divided into three categories based on
contribution of heat to the death: probable heat related cases, possible
heat-related cases and improbable heat-related cases. For the community
deaths, data were extracted from the death certificate, the pre-hospital
intervention report and attestation of death performed by the medical
team of Urgences-sante. For long-term care and hospitals, medical
records were consulted on site or faxed and data were extracted from
them. Results were tabulated according to risk factors derived from the
literature.
Two major underlying health conditions were identified in
heat-related deaths: cardiovascular problems and mental health problems.
Often, numerous underlying health conditions were present in an
individual. In addition, when analyzing the 32 reported community deaths
for people with mental illness, many of these people lived alone, and 14
out of 21 for whom information was available were contacted 24 hours
prior to their death by health care professionals, family members,
neighbours or friends. The chart review also revealed that the medical
files for the patients in long-term care facilities were lacking
information. Hence in these settings, the extent to which heat
contributed to death for these patients was more difficult to identify.
On typical summer days in Montreal, 70% of deaths from all causes
occurred in hospitals, followed by 14% in the community and 16% in
long-term care facilities. (14) During the 2010 heat wave, 52% of deaths
from all causes occurred in hospitals, while 31% occurred in the
community and 17% in long-term health care facilities. For heat-related
deaths during the heat wave, 93 occurred in the community (88%) and 13
occurred in long-term health care facilities and hospitals (12%).
Update of the heat response plan following the 2010 heat wave
In this paper, we highlighted the functioning of the MHRP and
regional surveillance system. The observations stemming from the 2010
heat surveillance system and the chart review prompted Montreal public
health and its partners to update its heat response plan and
surveillance system. It was decided that the sentinel indicators would
be the Info-sante calls, pre-hospital transports and community deaths.
The main advantage in using these indicators is that the data regarding
these events are available rapidly (the next day). In addition, it was
decided that during heat waves, the physician filling the attestation of
death would also use a section of the chart to determine if mortality is
probably, possibly or not related to heat, thus guaranteeing rapid
availability of information. Major changes to the MHRP also include the
onset of the Intervention level following two instead of three days of
temperatures reaching the threshold temperatures if Environment Canada
maintains its predictions of >33[degrees]C for the third day. Indeed,
it was observed that increase in mortality in the community occurred a
day earlier than the peak in total deaths. Furthermore, during the heat
wave, total deaths occurring at home in the community were twice the
normal expected value. This displacement of deaths, from hospitals to
the community, has also been observed during other heat waves. (15)
The results of the chart review performed during the heat wave
indicated that individuals over approximately 70 years of age and
suffering from cardiovascular disease were at higher risk during a heat
wave. Communication strategies have previously been developed for
specific vulnerable populations, including seniors. However, the chart
review also highlighted the important vulnerability of individuals with
mental illness in Montreal and of those who were drug- or
alcohol-dependent. Individuals with mental illness who died during the
heat wave were also younger, averaging approximately 60 years of age.
Family, friends and professionals may have been less aware that
individuals with certain mental illnesses were particularly vulnerable
during a heat wave, as can be implied by the data reporting that many
people with mental illness were contacted 24 hours prior to their death.
It was thus decided that there would be a specific communication
campaign during heat waves that targets individuals with mental
illnesses (in addition to the communication campaign already in place
targeting the elderly and young children). In addition, there would be
further preparation work with local health and social services centres,
community organizations and psychiatric hospitals to ensure that there
is proper outreach to vulnerable populations, including patients with
mental illness, during heat waves.
DISCUSSION
The MHRP and surveillance system as implemented have strengths and
limitations. The surveillance system provides the information necessary
for Montreal's public health department and its partners to decide
on the levels of interventions required during the summer period and
when there is a heat wave on the Montreal Island. This system is unique
because the information is very timely, especially with regards to
health indicators that are often available within the same day. This
surveillance system is based on the daily monitoring of several health
indicators that can respond rapidly during a heat wave; indeed, it is
able to detect slight increases in heat-related deaths even before
important increases are observed in the total number of deaths from all
causes. Some systems developed elsewhere are also based on daily
monitoring of indicators, such as mortality. In general, these systems,
including the one developed in Montreal, aim to reduce as much as
possible delays in transfer and analysis of health indicators. (16-19)
However, regarding health indicators, it is not clear if the increases
in heat-related Info-sante calls were prompted by the heat protection
measures presented in the mass media campaign that was occurring
simultaneously. In fact, as part of the preventive messages, the
population was encouraged to contact Info-sante for further information.
The Montreal heat wave in July 2010 was extreme both in duration and
intensity. It is not clear such a health outcome would occur if weather
criteria were met but with shorter duration and less intensity. In
addition, contrary to expectations, as can be seen from the community
mortality data, there was a protracted period of community mortality
(July 12th and 13th), even after most interventions were stopped because
of cooler temperatures. Recent studies have proposed that the intensity
and duration of a heat wave, and consequently associated mortality
during this period, could be best predicted if the cumulative effect of
several hot days is taken into consideration. (20) As previously
discussed, the MHRP and heat surveillance system were updated and
further actions were taken as a result of the information obtained
during the July 2010 heat wave in Montreal. Lessons learned from our
approach are important for any surveillance initiative regarding heat.
It is hoped that better communication methods for the vulnerable
populations and earlier intervention will diminish the health impact,
given the observation that although contacted by health care
professionals, family or friends 24 hours prior to their death, many
people with mental illness unfortunately died during the heat wave.
Future initiatives should focus on better identifying the vulnerable
populations and communicating preventive measures, pursuing the
identification of the most valuable health indicators, as well as
thoroughly evaluating the overall impact of the heat response plan and
its actions on mortality reduction during heat waves. The current paper
was not designed to assess whether the heat plan, as applied in 2010,
was effective in reducing mortality. Future research specifically aimed
at evaluating the effectiveness of the heat plan would allow one to
conclude whether changes in mortality are attributable to the
implementation of preventive measures in the heat plan.
Conflict of Interest: None to declare.
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Received: July 18, 2012
Accepted: January 24, 2013
Karine Price, MSc, [1] Stephane Perron, MD, MSc, FRCPC, [2] Norman
King, MSc [1]
Author Affiliations
[1.] Direction de sante publique de l'Agence de la sante et
des services sociaux de Montreal, Montreal, QC
[2.] Direction de sante publique de l'Agence de la sante et
des services sociaux de Montreal; Universite de Montreal, departement de
medecine sociale et preventive, Montreal, QC
Correspondence: Karine Price, Direction de sante publique de
l'Agence de la sante et des services sociaux de Montreal, 1301, rue
Sherbrooke Est, Montreal, QC H2L 1M3, Tel: 514-528-2400, Fax:
514-528-2459, E-mail: kprice@santepub-mtl.qc.ca
Table 1. Alert and Mobilization Levels in the
Montreal Heat Response Plan *
Alert Level Some of the Actions Undertaken by the
Montreal Public Health Department and
Partners During the 2010 Heat Wave
Normal * Preparation and application of
In effect Sept. education campaign
15 to May 15 * Updating of heat response plan
Seasonal Watch * Press release and distribution of
In effect May educational material for the population
15 to Sept. 15 via health and social services centres
and other distribution platforms
* Advisories transmitted to Info-Sante
and to the Health and Social Services
Agency for release in the
health care network
* Monitoring of the health
surveillance screen
* Preparation for further levels
Active Watch * Transfer of heat advisory to partners
In effect follow- * Advisories to the public via
ing a heat warning by different media on preventive measures
Environment Canada * Monitoring of the health surveillance
(forecast of tempe- screen and weather conditions
ratures [greater than * Intensification of surveillance and
of equal to] 30 [degrees]C application of preventive measures by
and Humidex [greater health care facilities
than or equal to] 40)
Alert * Monitoring of the health surveillance
In effect following screen and weather conditions
a forecast of * Advisories emitted to surrounding
3 consecutive days regional public health departments,
with average maximal the Agency and the Ministry of Health
temperatures [greater * Advisories to health care facilities
than or equal to] 33 by the Agency via the Civil security
[degrees]C and average advising committee
minimal temperatures
[greater than or equal * Preparation for intervention
to] 20 [degrees]C
Intervention * Mobilization and application of
In effect when temperature intervention measures by municipal,
thresholds regional and local public health
have been attained or partners. These actions can include
sanitary indicators information in the media, call for
are above normal levels awareness issued to health care
professionals, surveillance of
dehydration symptoms in patients,
extension of pool opening hours,
opening of air-conditioned shelters,
door-to-door campaign by municipal
partners to identify people suffering
from heat and in need of assistance
* Monitoring of the health surveillance
screen and weather conditions
* A detailed description of actions performed by the Montreal public
health department and partners at the municipal, regional and local
public health levels is available in Annexe 1 of the
"Report of the Public Health Director on the 2010 Montreal heat
wave" (8)(see Supplemental Appendix B).
Table 2. Underlying Health Conditions in Heat-related
Deaths from July 6 to 11, 2010 in Montreal,
Canada
Place of Death
Community Long-term
or Health Care
Emergency Facilities
Total Number of Deaths 93 12 *
Age (Average) 71.7 83.9
Underlying Health Condition ([dagger]) Number Number
of Cases of Cases
Cardiovascular/cerebrovascular problems
Coronary artery disease 13 8
Cardiac insufficiency 14 3
Cerebral vascular accident 4 2
Cardiovascular risk factors
Diabetes 27 4
Hypertension 43 6
Mental health illness
Schizophrenia 13 1
Alcoholism/drug addiction 13 0
Depression 1 0
Bipolarity 3 0
Dementia 3 7
Cancer 12 0
Asthma/COPD 14 1
Renal insufficiency 7 0
* One death occurred in a hospital and results are not shown here.
([dagger]) Information on all underlying health conditions was
present in 77 cases.
Numerous health conditions can be present in one individual.
