Extreme heat and blood pressure study published in JAMA Network Open
With our OCHIN partners, we studied how extreme heat relates to blood pressure across 4.2 million community health center visits
Created Sep 10, 2026 - Last updated: Sep 10, 2026
Extreme Heat Exposure and Blood Pressure in Community Health Center Patients has been published in JAMA Network Open. Brenda McGrath at OCHIN led the study, with CLAI’s Pedram Fard and Hossein Estiri as coauthors, as part of our CATALYST collaboration with OCHIN.
The team linked daily extreme heat exposure to 4,221,866 ambulatory visits with a blood pressure measurement at 2,554 community health centers in 40 states, covering the summers of 2019 through 2023. On extreme heat days, systolic blood pressure was 0.7 mm Hg lower and diastolic blood pressure 0.3 mm Hg lower than on other days. Adults 65 years and older showed larger reductions, with systolic pressure 1.1 mm Hg lower and diastolic pressure 0.8 mm Hg lower. The association peaked on the day of exposure and the day after, then weakened by the third day.
For an individual patient these shifts are modest. Summed across millions of visits, they bear on how clinicians interpret a blood pressure measured on a hot day and on cardiovascular risk assessment in the populations that community health centers serve.