(285) The Characteristics and Outcomes of ICU Admissions During Cold and Heat Waves From 2018 to 2022

Introduction: While previous studies have documented the relationship between weather changes and the exacerbation of certain acute illnesses, the effect that extreme temperatures might have on ICU admissions has not been investigated yet. This study aimed to evaluate the characteristics and outcomes of patients admitted to the ICU due to five conditions (stroke, sepsis, acute kidney injury, cardiovascular and pulmonary diseases) during heat waves (HW) and cold waves (CW).

Methods: We included adult patients admitted to the ICUs of the Mayo Clinic in Rochester, MN, between January and December. Patients were stratified based on the primary ICU admission diagnosis, defined by ICD-9 codes. Weather data were obtained from the National Oceanic and Atmospheric Administration. CW and HW were defined as at least two consecutive days with a daily average temperature (Tav) below the 5th percentile or above the 95th percentile of the daily Tav observed in Rochester, MN, between 2000 and 2022, respectively. Admissions occurring during CW & HW days and during the following seven days were compared to admissions occurring during the other days of the year.

Results: 50,733 patients were admitted to the ICU between 2018 and 2022. Of total ICU admissions, 11.7% and 8.5% occurred during CW and HW, respectively. The number of patients admitted daily to the ICU during HW was lower than during CW and normal temperature periods (p=0.036). The proportion of admissions for sepsis was higher during CW lower than during HW, while the opposite occurred for AKI, cardiovascular, and pulmonary diseases (p < 0.001). Compared to periods with normal weather, hospital mortality was higher during CW and lower during HW (p < 0.001). After adjustment for age, sex, admission diagnosis, and Charlson Comorbidity Index, HW were associated with lower hospital mortality than normal weather periods (OR 0.85, 95% CI 0.75 -0.97).

Conclusions: These results suggest that weather patterns, specifically CW and HW, can impact ICU admissions and patient outcomes. ICU admissions during CW were characterized by an higher proportion of sepsis cases and higher mortality rates, potentially increasing ICU burden. In contrast, HW were associated with a lower rate of daily ICU admissions and better mortality outcomes.