PB0895 - Changes in immature platelet fraction after major trauma: a prospective cohort study

Background: Alterations in platelet behaviour after severe injury are an important contributor to trauma-induced coagulopathy, but little is known about how haemorrhage and tissue injury influence platelet turnover.

Aims: To determine whether the immature platelet fraction (IPF) is associated with injury severity and clinical outcome after trauma.

Methods: We conducted a prospective observational cohort study of injured patients at a single major trauma centre. Using a Sysmex XE automated analyser, we measured the IPF at 2h, 24h and 72h post injury. We defined patients with an injury severity score (ISS) < 15 as mild-moderate and those with an ISS of >15 as severely injured.

Results: A total of 194 patients were included, with a median ISS of 13 (IQR 4-25) and an overall mortality of 12% (23/194). At 2h, the IPF in severely injured patients (5.0 (3.5-7.8)%) was significantly (p=0.001) higher than that in patients with mild-moderate injuries (3.9 (2.5-5.7)%). A similar trend was evident at 24h (6.4 (5.1-8.5)% vs 3.6 (2.8-7.8)%; p=0.03) and 72h (7.1 (5.0-10.2)% vs 4.8 (3.6-7.5)%; p=0.04), with a progressive increase in IPF between 2h and 72h in severely injured patients (Figure 1A). Platelet count showed the inverse pattern, with lower counts in severely injured patients at each timepoint and a progressive decline between 2h and 72h (Figure 1B). The mortality rate in patients with both IPF and platelet count below the cohort medians (11/35, 31.4%) was four-fold higher (p < 0.001) than that in the remainder of the cohort (12/159, 7.5%).

Conclusion(s): These results demonstrate that the IPF increases in the circulation in the acute phase after major trauma, and that low IPF values in the context of a low platelet count are associated with higher mortality. More detailed investigations of the origins and beneficial effects of circulating immature platelets after injury are warranted.