Department of Medicine, Western University, London, Ontario, Canada.
ICES, Toronto, Ontario, Canada.
Can J Public Health. 2022 Oct;113(5):686-697. doi: 10.17269/s41997-022-00665-1. Epub 2022 Aug 18.
Ontario's Harmonized Heat Warning and Information System (HWIS) brings harmonized, regional heat warnings and standard heat-health messaging to provincial public health units prior to periods of extreme heat.
Was implementation of the harmonized HWIS in May 2016 associated with a reduction in emergency department (ED) visits for heat-related illness in urban locations across Ontario, Canada?
We conducted a population-based interrupted time series analysis from April 30 to September 30, 2012-2018, using administrative health and outdoor temperature data. We used autoregressive integrated moving average models to examine whether ED rates changed following implementation of the harmonized HWIS, adjusted for maximum daily temperature. We also examined whether effects differed in heat-vulnerable groups (≥65 years or <18 years, those with comorbidities, those with a recent history of homelessness), and by heat warning region.
Over the study period, heat alerts became more frequent in urban areas (6 events triggered between 2013 and 2015 and 14 events between 2016 and 2018 in Toronto, for example). The mean rate of ED visits was 47.5 per 100,000 Ontarians (range 39.7-60.1) per 2-week study interval, with peaks from June to July each year. ED rates were particularly high in those with a recent history of homelessness (mean rate 337.0 per 100,000). Although rates appeared to decline following implementation of HWIS in some subpopulations, the change was not statistically significant at a population level (rate 0.04, 95% CI: -0.03 to 0.1, p=0.278).
In urban areas across Ontario, ED encounters for heat-related illness may have declined in some subpopulations following HWIS, but the change was not statistically significant. Efforts to continually improve HWIS processes are important given our changing Canadian climate.
安大略省的协调热警报和信息系统（HWIS）在极端高温期之前，为省级公共卫生部门提供协调的、区域性的热警报和标准的热健康信息。
2016 年 5 月实施协调 HWIS 是否与加拿大安大略省城市地区因与热有关的疾病而前往急诊室（ED）就诊的人数减少有关？
我们使用行政健康和户外温度数据，对 2012 年至 2018 年 4 月 30 日至 9 月 30 日进行了基于人群的中断时间序列分析。我们使用自回归综合移动平均模型来检查在实施协调 HWIS 后，ED 率是否发生了变化，调整了最高日温度。我们还检查了脆弱群体（≥65 岁或<18 岁、合并症患者、最近无家可归史的患者）和热警报区的效果是否不同。
在研究期间，城市地区的热警报变得更加频繁（例如，在多伦多，2013 年至 2015 年期间触发了 6 次事件，2016 年至 2018 年期间触发了 14 次事件）。ED 就诊率的平均值为每 10 万安大略省居民 47.5 例（范围为 39.7-60.1），每 2 周研究间隔一次，每年 6 月至 7 月达到高峰。最近无家可归史的人 ED 就诊率特别高（平均值为每 10 万 337.0 例）。尽管在某些亚人群中，HWIS 实施后率似乎有所下降，但在人群水平上没有统计学意义（率为 0.04，95%CI：-0.03 至 0.1，p=0.278）。
在安大略省的城市地区，由于 HWIS，某些亚人群中与热有关的疾病导致的 ED 就诊率可能有所下降，但这一变化在统计学上并不显著。鉴于我们不断变化的加拿大气候，努力不断改进 HWIS 流程非常重要。
