Summary of included studies of ASDH in elderly following systematic review of the literature
| Author, year | Location (period) | Country | No of hospitals/ Patients | Age for inclusion (years) | Age (years) % Male | Treatment | Outcomes measured | Risk factor analysis | STROBE criteria | ROBINS-I score |
| Wilberger et al, 199120 | Allegheny General Hospital (1982 to 1987) | USA | 1/28 | >65 | N/A | Craniotomy | Mortality, GOS at discharge | Age, ICP, GCS, timing of surgery; descriptive analyses (not in elderly group alone) | 17 | Moderate |
| Cagetti et al, 199221 | University of Genoa Medical School (January 1980 to December 1988) | Italy | 1/26 | >80 | 84.2 (mean) 57.7% | Surgical evacuation | Mortality, GOS at discharge | Age, mechanism, GCS, comorbidities; descriptive analyses (not in elderly group alone) | 10 | Serious |
| Jamjoom, 199222 | Frenchay Hospital (1980 to 1989) | UK | 1/27 | ≥75 | 79.2 (mean) 55.6% | Surgical evacuation | Mortality, GOS at 6 months | Age, sex, mechanism, GCS/ pupils, imaging, timing of surgery; χ2 test | 14 | Moderate |
| Kotwica and Jakubowski, 199223 | Medical University of Lodz (1984 to 1990) | Poland | 1/27 | >70 | N/A | Surgical evacuation | Mortality, GOS at discharge | Age, gender, GCS, imaging; descriptive analyses | 15 | Moderate |
| Massaro et al, 199624 | Centro Traumatologico Ortopedico (1982 to 1992) | Italy | 1/25 | >65 | N/A | DC | Mortality, GOS at 18 months | Age, gender, mechanism, GCS, timing of surgery, imaging; χ2 test/ Fisher’s exact test (not in elderly group alone) | 15 | Moderate |
| Koc et al, 199725 | Erciyes University (January 1986 to August 1995) | Turkey | 1/15 | ≥61 | N/A | Craniotomy | Mortality, GOS at 3 months | Age, gender, presenting GCS; χ2 test (not in elderly group alone) | 10 | Moderate |
| Petridis et al, 200926 | UKSH Campus Kiel | Germany | 1/119 | >65 | N/A 55.2% | Craniotomy, DC | Mortality, GOS discharge | GCS/ pupils, imaging, anticoagulation, ICP; χ2 test, ANOVA | 13 | Moderate |
| Hanif et al, 200927 | Beaumont Hospital (January 1999 to December 2003) | Ireland | 1/29 | >70 | 77.0 (mean) 59.7% | Surgical evacuation | Mortality, GOS at 6 months | Age, GCS; descriptive analyses (not in elderly group alone) | 13 | Moderate |
| Taussky et al, 201228 | Kontansspital Aarau (January 2002 to December 2007) | Switzerland | 1/37 | >65 | 73.0 (median) 46% | Craniotomy - 23 DC - 14 | Mortality at discharge Mortality, GOS at 6 months | Age, pupils, timing of surgery, GCS/ pupils, anticoagulants, comorbidities; descriptive analyses | 20 | Moderate |
| Hamed et al, 201640 | Rheinische Friedrich-Wilhelms University (January 2010 to December 2014) | Germany | 1/57 | >70 | N/A | Craniotomy, DC | GOS at 6 months | Age, TBI severity, timing of admission, surgical approach, antithrombotics, timing of surgery, duration of hospital stay, postoperative complications (not for elderly group alone) | 17 | Serious |
| Merzo et al, 201629 | Uppsala University Hospital (2008 to 2010) | Sweden | 1/24 | ≥65 | N/A | Craniotomy – 23 DC – 1 | Mortality, GOS at 6 months | Age, gender, comorbidities, mechanism, imaging; χ2, unpaired Student’s t-test (not for elderly group alone) | 17 | Moderate |
| Raj et al, 201630 | Helsinki University Hospital (January 2009 to December 2012) | Finland | 1/44 | ≥75 | 81.0 (median) 52% | Craniotomy, DC | Mortality at 1 and 3 years | Age, baseline functional status, residence, gender, anticoagulants, mechanism, GCS/ pupils; χ2 test, unpaired Student’s t-test, Mann-Whitney U test | 18 | Moderate |
| Benedetto et al, 201731 | Azienda Ospedaliero-Universitaria Pisana (June 2011 to December 2014) | Italy | 1/67 | >70 | 80.5 (median) 53.7% | Craniotomy | Mortality, GOS at 1 and 6 months | Age, imaging, GCS, antiplatelets; simple and multiple linear regression | 17 | Moderate |
| McGinity et al, 201732 | University of Texas Health Science Center (2005–2015) | USA | 1/34 | ≥80 | 84.0 (mean) N/A | Craniotomy – 32 DC – 2 | Mortality, GOS at 2 months (variable) | Age, mechanism, type of surgery, anticoagulants, GCS/ pupils, imaging, comorbidities; Fisher’s exact test, Mann-Whitney U test | 17 | Moderate |
| Won et al, 201733 | Goethe-University Hospital (January 2007 to December 2016) | Germany | 1/56 | ≥80 | 85.0 (mean) 43% | Craniotomy, DC | Mortality at discharge | GCS; univariate/multivariate logistic regression | 20 | Moderate |
| Monsivais et al, 201834 | University of Texas Health Science Centre (January 2006 to July 2016) | USA | 1/112 | ≥70 | N/A | Craniotomy – 101 DC – 11 | Mortality at discharge | Age, GCS, type of surgery; χ2 test/ Fisher’s exact test | 20 | Moderate |
| Akbik et al, 201935 | University of New Mexico Hospital (January 2013 to December 2017) | USA | 1/62 | ≥65 | 78.0 (median) 48% | Craniotomy, DC | Mortality, GOS at discharge and 3 months | Age, comorbidities, GCS/pupils, imaging, antithrombotics; Kruskal-Wallis, Fisher’s exact test | 15 | Moderate |
| Bus et al, 201936 | Academic Medical Centre (January 2000 to October 2015) | Netherlands | 1/84 | ≥65 | 75.0 (mean) 64.3% | Craniotomy – 74 DC – 10 | Mortality at discharge Mortality, GOS at 1 year | Age, gender, imaging, GCS/ pupils, age of SDH, imaging, timing of surgery, anticoagulation; χ2/ Fisher’s exact tests, Mann-Whitney U test, univariate logistic regression | 17 | Moderate |
| Sufaro et al, 201937 | Soroka University Medical Center (2006–2016) | Israel | 1/28 | >70 | 81.5 (mean) 53.6% | Craniotomy | Mortality, mRS score at discharge and 1 year | Age, gender, baseline status, antithrombotics, GCS, imaging, neurological deficit; descriptive analyses | 17 | Serious |
| Trevisi et al, 202038 | Ospedale Santo Spirito; Fondazione Policlinico Universitario A. Gemelli IRCSS; S. Anna University Hospital, UOC Neurochirurgia (January 2016 to December 2019) | Italy | 5/147 | ≥70 | 78 (mean) 58% | Craniotomy- 133 DC- 14 | Mortality, GOS at discharge and 6 months | Age, gender, comorbidities, GCS/pupils, imaging, side of SDH, size of craniotomy, timing of surgery, anticoagulants; χ2 test, univariate/multivariate logistic regression | 16 | Moderate |
| Younsi et al, 202039 | University Hospital Heidelburg (January 2006 to December 2016) | Germany | 1/27 | ≥80 | 84.0 (median) 60% | Craniotomy, DC | Mortality, GOS at discharge | Age, gender, comorbidities, GCS/pupils, imaging, surgical factors, anticoagulants; Fisher’s exact test, unpaired Student’s t-test | 21 | Serious |
ANOVA, analysis of variance; ASDH, acute subdural haematoma; DC, decompressive craniectomy; GCS, Glasgow Coma Score; GOS, Glasgow Outcome Scale; ICP, intracranial pressure; IRCSS, Istituto di Ricovero e Cura a Carattere Scientifico; mRS, modified Rankin Scale; N/A, not available; ROBINS-I, risk of bias in non-randomised studies of interventions; SDH, subdural haematoma; STROBE, Strengthening of Reporting of Observational Studies in Epidemiology; TBI, traumatic brain injury; UKSH, Universitätsklinikum Schleswig-Holstein; UOC, Unità Operativa Complessa.