Environmental heat and acute kidney injury in older adults: A matched case-control study

This matched case-control study examined the association between environmental heat exposure and hospital encounters with acute kidney injury (AKI) among adults, 66 years and older, in the province of Ontario, Canada. We matched 52,913 cases who had an AKI event during the warm seasons (April to September) of 2005 to 2012 with 174,222 controls who did not have an AKI event. We matched cases to controls on date, age, sex, residential status, income, and history of chronic kidney disease using a variable one to four matching ratio. We classified heat periods as three consecutive days where the 95th percentile of area-specific daily maximum temperature was reached or exceeded. We determined associations using conditional logistic regression. Compared to non-heat periods, high heat periods were significantly associated with greater risk of AKI (adjusted odds ratio 1.11, 95% confidence interval 1.00 to 1.23)