Effect of high elevation on deep vein thrombosis: a multicenter cohort study.

BACKGROUND

Prior research explored the effect of elevation on deep vein thrombosis (DVT) but primarily examined injuries at elevations <1000 or >4000 feet, excluding elevations in between, and focused on specific subsets of trauma patients. This study aimed to conduct a more detailed analysis of the relationship between elevation and DVT in all trauma admissions.

METHODS

This retrospective cohort study at four level I trauma centers included adult trauma patients (October 1, 2022 to October 1, 2023). Injury zip codes were used to define elevation. High-elevation (H-ELV) injuries (≥5000 feet) were compared with low-elevation (L-ELV) injuries (<5000 feet). Elevation was further categorized into 1000-foot increments. An alpha of <0.0001 defined statistical significance.

RESULTS

Of 8620 patients, 49% (4231) had L-ELV injuries and 51% (4389) had H-ELV injuries. Compared to patients with L-ELV injuries, those with H-ELV injuries were significantly older, had lower oxygen saturation and higher heart rate, suffered falls and sports injuries more often, and motor vehicle collisions less often, and had a higher rate of comorbidities, including alcohol use disorder and anticoagulant use. DVTs occurred significantly more often after H-ELV injuries than L-ELV injuries (1.9% vs. 0.5%, p<0.0001). For each 1000-foot increase in elevation, there was a corresponding 0.4% average increase in the rate of DVT (moderate R2=0.6). After adjustment for alcohol use disorder and oxygen saturation, H-ELV injuries were associated with a 3.8-fold increase (95% CI 2.3 to 6.4) in the risk of DVT when compared with L-ELV injuries.

CONCLUSIONS

Even after adjustment, H-ELV injuries were associated with 3.8 increased odds of developing a DVT compared with L-ELV injuries. There was a significant positive linear association between DVT and injury elevation, with the rate of DVT increasing with increasing elevation. This finding may suggest the need for enhanced screening or tailored DVT prophylaxis methods at higher elevation trauma centers to improve outcomes.

LEVEL OF EVIDENCE: Level IV.