Bimodal, But Not the Same: Persistent Late Peaks in Trauma Mortality.

Background: Trauma is a significant cause of morbidity and mortality, disproportionately affecting low- and middle-income countries (LMICs). Data from high-income countries (HIC) show an evolution of Trunkey's trimodal distribution of at-scene, first 48 h and after 7 days mortality to bimodal distribution caused by the flattening of the third peak. The mortality distribution in LMICs is not well described. This paper aims to temporally characterize in-patient trauma-related deaths and identify predictors of this mortality among adults in Pakistan.

Methods: Data from December 2021 to February 2023 were extracted from a multicenter, prospective trauma registry in Karachi, Pakistan. Data on demographics, injury details including injury severity scores (ISS), inhospital care, and outcomes for admitted adult (≥ 18 years) patients not referred from another facility were extracted. The primary outcome was in-patient mortality categorized as within 48 h, after 48 h but within 7 days and after 7 days of injury. Multivariable analyses were done using multiple cox-regression to assess the association of patient and injury characteristics with early (< 48 h) and late mortality (> 48 h).

Results: We enrolled 1596 patients. The majority were males (80.70%), aged 18-40 years (55.33%). Half of the patients were admitted with moderate ISS (45.49%). Of these, 293 died (18.36%). Deaths were mainly due to road traffic crashes (66.55%) and head injury (84.98%). An equal proportion of mortality was observed in the < 48 h and day 2-7 groups. One vague mortality peak was also identified at > 7 days (n = 115). The adjusted hazard ratio for early mortality was 15% higher (95% CI 1.13, 1.18) for every one-unit increase in the ISS score. The presence of multiple co-morbidities (AHR = 4.95 95% CI 1.31, 18.68) and head injury (AHR = 15.25 95% CI 3.82, 60.81) were associated with late mortality.

Conclusions: In conclusion, our trauma mortality pattern aligns partially with Trunkey's 1983 trimodal distribution, showing a persistent late mortality attributed to deaths from complications. This highlights an urgent need for improvements in trauma care to reduce late-stage mortality. Further in-depth analysis is required to understand the underlying mortality drivers among admitted patients.