Abstract 232: Three-Dimensional Models of Complex Interactions Between Age, Prehospital Blood Pressure, and Mortality in Major Traumatic Brain Injury
Bibliographic record
Abstract
Background: Traumatic brain injury (TBI) studies with extensive prehospital data linked to trauma center (TC) outcomes have been small. Thus, risk adjusters like age and systolic BP have been treated dichotomously (e.g. age ≥55, SBP <90). In contrast, the size and linkage rate (98%) of the EPIC Study allows complex analysis. Hypothesis: The interactions between age, SBP, and mortality are neither simple nor dichotomous. Methods and Inclusion: Major TBI cases, age ≥10, in EPIC (NIH 1R01NS071049) before TBI guideline implementation (1/07-3/14). Logistic regression was used to associate death with age and lowest EMS SBP, adjusted for confounders, and fitted nonparametrically using penalized thin plate regression splines through the generalized additive model. Results: Included were 13,435 cases (Excl: 6.2% missing data; Med. age 46; 67.8% male). The Figure shows 3D planar images of the associations between adjusted risk of death (vertical axis), age and SBP. Fig A reveals: 1) there is no “hypotension threshold” below 120 mmHg at any age and this inflection point increases to 135 in older adults; 2) the optimal SBP vs outcome “valley” is very broad (e.g. ~120-180 in the young) and increases with age (~135-190 in the elderly). Figs B/C reveal: 1) mortality increases across the entire spectrum of age, 2) in hypotensive cases (SBP <90), mortality increases linearly with increasing age, 3) in non -hypotensive patients, the adjusted risk of death increases much more rapidly after age 40. Conclusion: Due to the small size of extant EMS studies, the evidence supporting parameters in triage guidelines (e.g. “older adults”) and EMS treatment guidelines (e.g. SBP <90) is weak. This analysis reveals that: 1) the interactions between age and SBP are far more complex than previously understood, 2) the rapidly-increasing risk for “older adults” with TBI begins around age 40, 3) the inflection point for hypotension is much higher than current guidelines suggest and increases steadily with age.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.010 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.013 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".