Diagnostic Role of Tau Proteins in Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis

Table 1

Descriptive characteristics of the included studies.

S.N.	Author and year of publication	Study country	Study design	Sample size (cases, controls)	Age (in cases)	Age (in controls)	Gender () (in cases)	Gender () (in controls)	Variable(s) measured	Findings
1.	Abu-Rumeileh et al., [11]	Italy	Case-control	80, 43			1.35	1.04	t-tau; p-tau; p-tau/t-tau	ALS presented significantly high t-tau () and lowered p-tau/t-tau ratio () than in controls. No differences in the level of p-tau ().
2.	Agnello et al., [12]	Italy	Case-control	197, 35	65 (61-70)	67 (54-74)	1.21	1.21	t-tau; p-tau; p-tau/t-tau	ALS patients presented a significantly lower p-tau/t-tau () and significantly increased t-tau (). No significant differences in the level of p-tau were observed ().
3.	Bourbouli et al., [17]	Greece	Case-control	32, 17			1.13	1.125	t-tau; p-tau	Significantly increased t-tau () in ALS as compared to controls. No significant differences in the level of p-tau ().
4.	Lanznaster et al., [15]	France	Case-control	123, 90	66.06	67.45	1.66	1.32	t-tau; p-tau; p-tau/t-tau	No significant differences in p-tau (), t-tau (), and p-tau/t-tau ratio () in ALS and controls.
5	Paladino et al., [16]	Italy	Case-control	57, 110			1.71	1.75	t-tau	No significant differences in t-tau levels between ALS and controls ().
6.	Scarafino et al., [13]	Italy	Case-control	85, 51			1.78	0.75	t-tau; p-tau; p-tau/t-tau	Significantly higher t-tau in ALS as compared to controls (). p-tau/t-tau was significantly reduced (). No significant difference in p-tau ().
7.	Wilke et al., [14]	Germany	Case-control	60, 120	67.34 (60.05-74.43)	64.14 (55.52-72.04)	1.30	1.07	t-tau; p-tau; p-tau/t-tau	Levels of p-tau did not differ significantly between cases and controls (). Significantly higher t-tau () while significantly lower p-tau/t-tau () in ALS as compared to controls.

Age is expressed in median (IQR) or or mean. Gender is expressed as the quotient of male and female.