Table 1.

Characteristics of the studies included

Author (year)	Data collection era	Country	Study design	Sample size	Age	TBI severity	Follow-up Duration (years)	SMR (95% CI)	LE (years)	Included in meta-analysis (y/n)
Baguley et al., 2012 [49]	1990–2007	Australia	Retro	2545	16–70 at time of injury	GCS < 9	9.3 (range, 2–19.5)	3.19 (95% CI, 2.80–3.60).		y
Baguley et al., 2008 [47]	1990–2009	Australia	Retro	966	16–70	GCS < 9	10.5 (range, 1.7–18.8)	13.2		y
Brooks et al., 2021 [30]	1988–2019	US	Retro	14,803	≥ 16	GCS < 13	1 y		Lower than age- and sex-matched general population (GP). - Walks well: absolute reduction ~ 7–8 y at age 20, ~ 4 y at age 60; relative reduction 13–15% (women), 14–20% (men). - Greater functional limitations: lower LE. - Non-ambulatory, fed by others: LE = 24 y at age 20 (both sexes); reduction of 33.1 y (58%) in men and 37.9 y (61%) in women vs. GP	y
Brooks et al., 2015 [31]	1988–2010	US	Population based cohort	12,481	≥ 16	GCS < 13	≥ 1 y	2.4 (95% CI, 2.2–2.6)	The estimates of age- and sex-specific LE were lower than those of the U.S. GP. LE was related to the severity of disability (walking and feeding skills).	y
Brooks et al., 2013 [32]	1988–2011	US	Retro	7228	≥ 16	GCS < 13	1–20 years	2.1 (95% CI, 1.9–2.3)		y
Cameron et al., 2008 [33]	1988–1991	US	Population-based matched cohort	1290	18–64;	minor to severe TBI (ISS)	10 y			y
Claridge et al., 2010 [34]	1985–1999	US	Retro	7800	< 16 = pediatric, 16–65 = adult, > 65 = elderly);	moderate/severe vs. mild (GCS);	5–20 years			y
Colantonio et al., 2008 [46]	1993–1995	Canada	Retro	2721	≥ 15;	moderate to severe TBI (AIS)	up to 9 years			y
Dams-O’Connor et al., 2015 [35]	1989; 2000	US	Retro	4178 for GOS-E; 7817 for DRS	≥ 16	GCS < 13	up to 9 years			y
Esterov et al., 2021 [36]	1987–1999	US	Retro	1257	< 16, 16–65, > 65;	GCS < 13	mean time of 10 years			y
Flaada et al., 2007 [37]	1985–1999	US	Retro	1433	16–80	Mild Mod/Sev (GCS)	5 y			y
Forslund et al., 2019 [51]	2005–2007	EU	Pro	97	16–65;	GCS < 13	10 y			y
Groswasser et al., 2017 [53]	1979–1985	Israel	Pro	279	mean age at injury was 26.6 years (SD = 11.87), and the median was 23.0 years	mild to severe (GCS)	22–27 y		Shortening of LE in comparison with the GP is 3.58 years. Estimated shortening of LE by severity for mild, moderate and severe injury were − 0.51, 4.11 and 13.77 years, respectively.	y
Harrison-Felix et al., 2015 [38]	2001–2010	US	Retro	6913	≥16	GCS < 13	up 10.2 year	2.23 (95% CI, 2.11–2.35)	On average, reduced LE by 9 years.	y
Harrison-Felix et al., 2012 [39]	1988–2009	US	Retro	8573	≥ 16	GCS < 13	up 20.3 years	2.25 (95% CI, 2.10–2.40)	On average, reduced LE by 6.7 years.	y
Harrison-Felix et al., 2006 [40]	1988–2001	US	Pro	2140	≥ 16	GCS < 9	mean 3.1 years (range, 1–11.8 years)			y
Maidan et al., 2017 [50]	2013	EU	Cross-sectional	374,636	0–85+;	head injury ICD code;
McCrea et al., 2021 [47]	2014–2018	Canada	Pro	434	≥ 17	GCS 3–12;	Up 1y
McMillan et al., 2011 [52]	1995–1996	UK	Retro	757	≥ 15	GCS < 13	up to 13 years
Nakase-Richardson et al., 2012 [41]	1988–2009	US	Retro	396	≥ 16	GCS = 3	1–5 years			n
Ratcliff et al., 2005 [42]	1974–1984; 1988;1989	US	Pro	642	≥ 14	head injury ICD code;	1–18 years	2-fold increased risk for mortality compared to the general population.		y
Selassie et al., 2005 [43]	1999–2001	US	Retro	3679	≥ 16	severe TBI (AIS)	1 y	7.1 (95% CI, 6.3–7.9) within 15 months of hospital dis- charge. Reported SMRs for selected causes of death and stratified by age (95% CI).		y
Ventura Harrison-Felix et al., 2010 [44]	1988–2003	US	Retro	18,988	≥ 15	AIS 1–6	1–20 y	2.47 (95% CI, 2.31–2.65).	On average, reduction of 6 years.	y
Wiegers et al., 2021 [54]		EU, UK, Australia	Pro	874	≥ 16	GCS < 9	0.5 y			y
Wilkins et al., 2019 [45]		US	Pro	559	16–80	GCS < 9	2 y			y