Abstract TP171: Nationwide Diurnal Pattern Among Intracerebral Hemorrhage Incidence and Volume

Introduction: Intracerebral hemorrhage (ICH) incidence follows both seasonal and diurnal patterns noted in the literature. These differences have been attributed to variations in the coagulation cascade, blood pressure, and sleep-wake cycle that all have their own noted rhythmicity. The purpose of this analysis was to validate these trends in a large nationwide database of automated ICH detection scans and evaluate for differences in hematoma volume by image acquisition time.

Methods: Serial non-contrast head CT (NCHCT) data, processed with an automated imaging software (iSchemaView), was acquired from U.S. hospitals between 1/1/2020 and 12/31/2021. Final exclusion criteria included: (1) patient age ≤ 25, (2) hematoma volume ≥ 100 ml, (3) hematoma volume ≤ 0.4 ml. Imaging time was subdivided into three epochs: (1) Night: 23:00h-06:59h, (2) Day: 07:00h-14:59h, and (3) Evening: 15:00h-22:59h.

Results: A total of 19,397 scans were included in the final analysis with a median ICH volume of 2.9 ml; 15.6% of these scans had volumes above 30 ml. Peak imaging occurred around noon. Hematoma volume was significantly different across timepoints (p = 0.003), with ICHs presenting at night (average volume 14.2 ml) larger than those presenting during the day (12.9 ml, p = 0.002) or evening (13.0 ml, p = 0.012).

Conclusion: In this real world, multi-site data set, we show similar diurnal trends in ICH incidence and can detect subtle differences in volume based on time of imaging. Further research is required to elucidate the potential underlying mechanisms for these differences.