RT Journal Article SR Electronic T1 Effects of diurnal temperature range on first-ever strokes in different seasons: a time-series study in Shenzhen, China JF BMJ Open JO BMJ Open FD British Medical Journal Publishing Group SP e033571 DO 10.1136/bmjopen-2019-033571 VO 10 IS 11 A1 Lin Lei A1 Junzhe Bao A1 Yanfang Guo A1 Qiong Wang A1 Ji Peng A1 Cunrui Huang YR 2020 UL http://bmjopen.bmj.com/content/10/11/e033571.abstract AB Objective Diurnal temperature range (DTR) is an important meteorological indicator of global climate change; high values of DTR may induce stroke morbidity, while the related high-risk periods and sensitive populations are not clear. This study aims to evaluate the effects of DTR on first-ever strokes in different seasons and in relation to sensitive populations.Methods We collected data on 142 569 first-ever strokes during 2005–2016 in Shenzhen. We fitted a time-series Poisson model in our study, estimating the associations between DTR and first-ever strokes, with a distributed lag non-linear model. Then, we calculated strokes attributable to high DTR in different genders, age groups, education levels and stroke subtypes.Results High DTR had a significant association with first-ever strokes, and the risk of stroke increased with the rise of DTR in the summer and winter. In total, 3.65% (95% empirical CI (eCI) 1.81% to 5.53%) of first-ever strokes were attributable to high DTR (5.5°C and higher) in the summer, while 2.42% (95% eCI 0.05% to 4.42%) were attributable to high DTR (8°C and higher) in the winter. In the summer, attributable fraction (AF) was significant in both genders, middle-aged and old patients, patients with different levels of education, as well as patients with cerebral infarction (CBI); in the winter, AF was significant in middle-aged patients, patients with primary and lower education level, as well as patients with CBI.Conclusions High DTR may trigger first-ever strokes in the summer and winter, and CBI is more sensitive than intracerebral haemorrhage to DTR. Most people are sensitive to high DTR in the summer, while middle-aged and low-education populations are sensitive in the winter. It is recommended that the DTR values be reported and emphasised in weather forecast services, together with the forecasts of heat and cold.