Determinants of Economic Costs Following Road Traffic Injuries in Canada: A Quantile Regression Forests Machine Learning Approach
Bibliographic record
Abstract
Introduction: This study aimed to identify major determinants of the cost of road traffic (RT) injuries, rank their importance, and assess their effects on different quantiles of cost distribution. Methods: This study analyzed data collected from 1372 Canadian RT survivors from July 2018 to March 2020. Costs, including healthcare and lost productivity costs over a year following RT injury, were estimated for each participant in 2023 Canadian dollars. Productivity loss was measured using the Institute for Medical Technology Assessment Productivity Cost Questionnaire. We considered 24 potential determinants of costs, which were grouped into five domains: sociodemographic, psychological, health, crash, and injury factors assessed during baseline interview. We employed a quantile regression forests machine learning approach alongside classical quantile regression to analyze costs. These methods were selected to capture heterogeneous effects across cost distribution, which are overlooked by traditional mean-based models, and to inform policy decisions targeting high-cost subgroup. Results: The results showed that the 10th, 50th, and 90th quantiles of costs were $1,141.9, $7,403.1, and $49,537.5, respectively. ISS, GCS, and age were the top three influential variables among low-cost, medium-cost, and high-cost patients. ISS, GCS, age, sex, employment status, and living situation were common major determinants at all quantiles. Ethnicity was selected as an important determinant at the 50th and 90th quantiles. Education level, years lived in Canada, somatic symptoms severity, psychological distress, HRQoL, road user type, and head, torso, spine/back, and lower extremity injuries were selected only for high-cost patients (90th quantile). Classical quantile regression showed that selected major predictors disproportionately affected low-cost, middle-cost and high-cost patients. Conclusion: High-cost patients were more likely to be older, retired, less educated, and have worse clinical and psychological indicators. These insights can guide targeted prevention and resource allocation strategies to reduce the economic burden of RT injuries.
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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 | 0.003 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".