Plasma matrix metalloproteinase-9 levels predict intensive care unit mortality early after severe traumatic brain injury

ABSTRACT

Objectives: Matrix metalloproteinase-9 (MMP-9) is an inducible metalloproteinase that can degrade the cerebrovascular matrix leading to disruption of the blood–brain barrier and exacerbation of oedema in neurotrauma. Therefore, our aim was to determine whether MMP-9 plasma levels were associated with intensive care unit (ICU) mortality after severe traumatic brain injury (TBI) despite the presence of extracerebral injuries.

Methods: This cohort enrolled 80 patients who suffered severe TBI (Glasgow Coma Scale: 3–8 at hospital admission). The plasma MMP-9 level was determined by enzyme-linked immunosorbent assay assay at ICU admission.

Results: Severe TBI was associated with a 32.5% ICU mortality rate. There was no association between the presence of extracerebral injuries (72.5% of the patients) and ICU mortality (P = 0.419). Higher plasma MMP-9 concentrations were associated with fatal outcome: 181.1 ± 16.0 ng/mL for survivors and 257.0 ± 23.2 ng/mL for nonsurvivors (mean ± S.E.M., P = 0.009). In contrast, there was no significant difference between MMP-9 levels and associated lesions: 220.8 ± 26.3 ng/mL for isolated TBI and 196.8 ± 15.8 ng/mL for patients with extracerebral injuries (P = 0.397).

Conclusion: Increased plasma MMP-9 levels predicted short-term fatal outcome following severe TBI, regardless the presence of extracerebral injuries.

KEYWORDS:

• Severe TBI
• MMP-9
• biomarker
• outcome

Declaration of interest

The present study received financial support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; research grant 568691/2008-3) and from Fundação de Amparo à Pesquisa do Rio Grande do Sul (FAPERGS; research grant 09/0041-5, 1630-25.51/09-0).