Association of capillary refill time with mortality in adult trauma patients: a secondary analysis of the CRASH-2 randomised controlled trial data

Background : Trauma-related injuries account for up to 4.4 million deaths annually worldwide. Failure to identify haemorrhage in trauma patients increases mortality. This study examines the association of capillary refill time (CRT) and mortality in adult trauma patients, especially in the subgroup with normal heart rate (HR) and blood pressure (BP). Methods : This retrospective observational study analysed data from the CRASH-2 trial, conducted in 274 hospitals across 40 countries and 5 continents between May 2005 and January 2010. A total of 19,054 out of 20,207 adult trauma patients with recorded CRT and complete dataset were included. CRT was categorized as ≤ 2, 3-4, and ≥ 5 seconds. The primary outcome was 28-day mortality, while secondary outcomes included need for transfusion, surgical intervention and thromboembolic events. Univariable and multivariable logistic regression analysis were conducted, incorporating random effects for continent/cluster. Receiver operating characteristic curves were used to assess the discriminatory ability of CRT measurement Results : Among the patients, 6,756 (35.5%) had a CRT ≤2 seconds, 9,142 (48%) had a CRT of 3–4 seconds, and 3,156 (16.6%) had a CRT ≥5 seconds. Compared to the reference category (CRT ≤2 seconds), the odds of death were significantly higher in patients with CRT of 3–4 seconds (OR 1.7, 95% CI 1.6–1.9) and CRT ≥5 seconds (OR 3.2, 95% CI 2.8–3.5). Higher CRT was also associated with an increased likelihood of blood transfusion, surgical intervention, and thromboembolic events. However, CRT demonstrated poor test accuracy for mortality prediction, with area under the curve (AUC) values around 0.6. Conclusion : CRT is associated with increased mortality and adverse outcomes in trauma patients. However, due to its low predictive accuracy, CRT alone is insufficient as a screening tool in pre-hospital settings. Nevertheless, it may provide additional value in patients with normal blood pressure and heart rate. In bleeding trauma patients, an increasing CRT is linked to higher mortality risk, with a CRT ≥5 seconds being particularly predictive of worse outcomes, even in patients with stable vital signs.