Elsevier

Public Health

Volume 128, Issue 7, July 2014, Pages 628-635
Public Health

Original Research
Using an Emergency Department Syndromic Surveillance System to investigate the impact of extreme cold weather events

https://doi.org/10.1016/j.puhe.2014.05.007Get rights and content

Abstract

This report describes the development of novel syndromic cold weather public health surveillance indicators for use in monitoring the impact of extreme cold weather on attendances at EDs, using data from the 2010–11 and 2011–12 winters.

A number of new surveillance indicators were created specifically for the identification and monitoring of cold weather related ED attendances, using the diagnosis codes provided for each attendance in the Emergency Department Syndromic Surveillance System (EDSSS), the first national syndromic surveillance system of its kind in the UK. Using daily weather data for the local area, a time series analysis to test the sensitivity of each indicator to cold weather was undertaken.

Diagnosis codes relating to a health outcome with a potential direct link to cold weather were identified and assigned to a number of ‘cold weather surveillance indicators’. The time series analyses indicated strong correlations between low temperatures and cold indicators in nearly every case. The strongest fit with temperature was cold related fractures in females, and that of snowfall was cold related fractures in both sexes.

Though currently limited to a small number of sentinel EDs, the EDSSS has the ability to give near real-time detail on the magnitude of the impact of weather events. EDSSS cold weather surveillance fits well with the aims of the Cold Weather Plan for England, providing information on those particularly vulnerable to cold related health outcomes severe enough to require emergency care. This timely information aids those responding to and managing the effects on human health, both within the EDs themselves and in the community as a whole.

Introduction

There is a substantial evidence base demonstrating both the direct and indirect impact of cold weather on health.1 Increases in both morbidity (e.g. incidence of respiratory disease, heart attacks, falls and injuries, hypothermia) and mortality are observed during winter each year.2, 3, 4, 5 Periods of extreme cold weather, where temperatures are significantly lower than what is usual for the time of year, even for a short period of time, have the potential to further impact on human health through direct exposure to lower temperatures, and associated adverse conditions, such as snow and ice.6

Public Health England (PHE) plays a major role in the UK public health planning for extreme weather events, including flooding, drought and extreme hot and cold temperatures.4, 7 PHE syndromic surveillance systems have been used successfully to monitor the public health impact of hot weather as part of the Heatwave Plan for England.8, 9 More recently, PHE syndromic surveillance systems have also been feeding into the recently established Cold Weather Plan for England,10 with the provision of near real-time information during extreme cold weather events.11

The Cold Weather Plan is a cross government plan, developed by the Department of Health, PHE and the Met Office. It aims to reduce preventable mortality and morbidity due to severe (hazardous) cold weather through a series of Met Office generated cold weather alerts, which link to a number of public health actions. The public health recommendations range from long-term planning and preparation, to major incident emergency response.

Syndromic Surveillance is the (near) real-time collection, analysis, interpretation and dissemination of health-related data to enable the early identification of the impact (or lack of impact) of threats to human or veterinary health requiring public health action.12 PHE coordinates a programme of syndromic surveillance including systems utilizing data from a telephone health advice service, a general practitioner (GP) network and a GP out of hours service to routinely monitor the emergence and spread of common infectious diseases, and the public health impact of non-infectious events, in the community, in near real-time.13 This report describes the development of novel syndromic surveillance cold weather indicators in the Emergency Department Syndromic Surveillance System (EDSSS)14, 15 for use in monitoring the direct impact of extreme cold weather on attendances at EDs, using data from the 2010–11 and 2011–12 winters. The aim of this work was to establish the effectiveness of the EDSSS in detecting and monitoring in near real-time the health impact of extreme cold weather and to develop new ‘cold weather indicators’ for integration into routine surveillance, in support of the Cold Weather Plan.

Section snippets

EDSSS reporting

Attendance data from emergency departments participating in the EDSSS were selected for this study based upon two criteria: continued, uninterrupted daily reporting during the study period (November 1, 2010 to March 31, 2011 and November 1, 2011 to March 31, 2012); and use of a detailed clinical diagnosis coding system with sufficient detail to allow the construction of cold weather specific syndromic indicators. Two EDs (both located within the same, large, English city) met these criteria,

Cold weather periods

During winter of 2010–11 the Met Office issued severe weather warnings for the UK.18 Several prolonged periods of severe winter weather were experienced, with high levels of snow fall and record low temperatures during November and December 2010 (Fig. 1a). The winter of 2011–12 was on the whole milder, experiencing fewer cold weather periods, which occurred during January and February 2012 (Fig. 1b).

ED attendances

In total, 168,636 attendances were recorded from the two EDs (mean daily attendances = 557:

Main findings

This investigation aimed to develop ED specific syndromic indicators to improve national cold weather surveillance, through the ability to identify and quantify any direct impact of severe winter weather on public health in near real-time, and to use these indicators to quantify the direct impact of cold weather on ED attendances during two winters. The findings illustrated that winter weather did impact on both the overall number of attendances each day, and in the types of diagnoses

Acknowledgements

The authors acknowledge the contribution and support from the ED clinicians and Trust staff; the ongoing support of the College of Emergency Medicine; the technical support provided by Ascribe Ltd and L2S2 Ltd in developing the EDSSS system. The authors thank Ian Barlow and Dann Piper (Leeds Teaching Hospitals NHS Trust) for valuable personal communications and Christophe Sarran (Met Office) for providing meteorological data used in the analysis.

Ethical approval

None sought.

Funding

This surveillance is undertaken as

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