Traumatic brain injury during COVID-19 pandemic-time-series analysis of a natural experiment.

Objectives: This study aims to find if the incidence and pattern of traumatic brain injury (TBI) changed during the COVID-19pandemic. We also aim to build an explanatory model for change in TBI incidence using Google community mobility and alcohol sales data.

Design: A retrospective time-series analysis.

Setting: Emergency department of a tertiary level hospital located in a metropolitan city of southern India. This centre is dedicated to neurological, neurosurgical and psychiatric care.

Participants: Daily counts of TBI patients seen between 1 December 2019 and 3 January 2021 (400 days); n=8893. To compare the profile of TBI cases seen before and during the pandemic, a subset of these cases seen between 1 December 2019 and 31 July 2020 (244 days), n=5259, are studied in detail.

Results: An optimal changepoint is detected on 20 March 2020 following which the mean number of TBI cases seen every day has decreased and variance has increased (mean 1=29.4, variance 1=50.1; mean 2=19.5, variance 2=59.7, loglikelihood ratio test: χ=130, df=1, p<0.001). Two principal components of community mobility, alcohol sales and weekday explain the change in the number of TBI cases (pseudo R=58.1). A significant decrease in traffic accidents, falls, mild/moderate injuries and, an increase in assault and severe injuries is seen during the pandemic period.

Conclusions: Decongestion of roads and regulation of alcohol sales can decrease TBI occurrence substantially. An increase in violent trauma during lockdown needs further research in the light of domestic violence. Acute care facilities for TBI should be maintained even during a strict lockdown as the proportion of severe TBI requiring admission increases.