Characteristics of included studies
| First author | Year of study publication | Countries | Number of hospitals | Number of patients included | Biomarkers assessed | Multivariate* AUROC† |
| Ingebrigtsen58 | 1995 | Norway | 1 | 50 | S-100β | ✗/✗ |
| Waterloo59 | 1997 | Norway | 1 | 7 | S-100β | ✗/✗ |
| Ingebrigtsen60 | 1999 | Norway | 1 | 50 | S-100β | ✗/✗ |
| Ingebrigtsen61 | 2000 | Norway, Sweden and Denmark | 3 | 182 | S-100β | ✗/✗ |
| Herrmann62 | 2001 | Germany | 1 | 69 | S-100β, NSE | ✓/✓ |
| De Kruijk63 | 2002 | Netherlands | 1 | 107 | S-100β, NSE | ✓/✗ |
| Townend64 | 2002 | UK | 4 | 148 | S-100β | ✓/✓ |
| de Kruijk65 | 2003 | The Netherlands | 1 | 111 | S-100β, NSE | ✓/✗ |
| Savola66 | 2003 | Finland | 1 | 199 | S-100β | ✓/✓ |
| Stranjalis67 | 2004 | Greece | 1 | 100 | S-100β | ✓/✓ |
| de Boussard68 | 2005 | Sweden | 3 | 122 | S-100β | ✗/✗ |
| Stålnacke69 | 2005 | Sweden | 1 | 88 | S-100β, NSE | ✓/✗ |
| Stapert70 | 2005 | The Netherlands | 1 | 50 | S-100β | ✗/✗ |
| Bazarian71 | 2006 (BI) | USA | 1 | 35 | S-100β, C-tau | ✗/✓ |
| Bazarian72 | 2006 (RNN) | USA | 1 | 96 | S-100β | ✗/✓ |
| Bulut73 | 2006 | Turkey | 1 | 60 | C-tau | ✗/✗ |
| Naeimi74 | 2006 | Austria | 1 | 45 | S-100β, NSE | ✗/✗ |
| Sojka75 | 2006 | Sweden | 1 | 98 | S-100β, NSE | ✓/✗ |
| Jakola76 | 2007 | Norway | 3 | 89 | S-100β | ✓/✗ |
| Stålnacke77 | 2007 | Sweden | 1 | 69 | S-100β, NSE | ✓/✗ |
| Lima78 | 2008 | Brazil | 1 | 50 | S-100β | ✗/✗ |
| Ma79 | 2008 | USA | 1 | 50 | C-tau | ✗/✗ |
| Schütze80 | 2008 | Germany | 1 | 74 | S-100β, NSE | ✓/✗ |
| Müller81 | 2009 | Norway | 1 | 93 | S-100β | ✓/✗ |
| Kleinert82 | 2010 | Germany | 1 | 73 | S-100β | ✗/✗ |
| Meric83 | 2010 | Turkey | 1 | 80 | NSE | ✗/✓ |
| Topolovec-Vranic84 | 2011 | Canada | 1 | 141 | S-100β, NSE | ✓/✓ |
| Metting85 | 2012 | The Netherlands | 1 | 94 | S-100β, GFAP | ✓/✗ |
| Okonkwo86 | 2013 | USA | 3 | 215 | GFAP | ✓/✓ |
| Abbasi87 | 2014 | Iran | 2 | 109 | S-100β | ✗/✗ |
| Diaz-Arrastia88 | 2014 | USA | 3 | 206 | GFAP, UCHL-1 | ✗/✓ |
| Ryb89 | 2014 | USA | 1 | 150 | S-100β | ✓/✓ |
| Heidari90 | 2015 | Iran | 1 | 176 | S-100β | ✓/✗ |
| Dey91 | 2016 | India | 1 | 20 | S-100β, UCHL-1 | ✗/✗ |
| Korley28 | 2016 | USA | 2 | 311 | C-tau, GFAP, UCHL-1 | ✓/✓ |
| Yang92 | 2016 | China | 1 | 76 | miR-93, miR-191, miR-499 | ✗/✗ |
*The association between protein biomarker(s) and outcome(s) was assessed using a multivariate regression model.
†The prognostic value of protein biomarker(s) was assessed using an area under the receiver operating characteristic curve (AUROC).
BI, brain injury; C-tau, cleaved tau; GFAP, glial fibrillar acidic protein; miR, microRNA; NSE, neuron-specific enolase; RNN, restorative neurology and neuroscience; UCHL-1, ubiquitin carboxy-terminal hydrolase L1.