Table 3. Review findings on all-cause mortality.

Study	Outcome	Treatment status	Comparator	Effect estimate (95% CI)
Peng et al. (2021) [42]	All-cause mortality	Treated	Untreated	RR 0.95 (0.75–1.22)
	All-cause mortality; age <65–70 years			RR 0.50 (0.29–0.85)
	All-cause mortality; age > = 65–70 years			RR 1.08 (0.91–1.28)
Reyes Domingo et al. (2019) [38]	All-cause mortality; adults (>18 years)	Treated	Untreated	HR 1.91 (0.65–5.60)
	All-cause mortality; adults (<65 or <70 years)			IRR 0.63 (0.40–0.99
				HR 0.36 (0.19–0.66)
	All-cause mortality; adults (>65 years)			HR 1.91 (0.65–5.60)
	All-cause mortality; females			IRR 0.99 (0.85–1.16)
				1.08 (0.80–1.48)
	All-cause mortality; males			IRR 1.24 (0.89–1.16)
				1.43 (0.87–2.34)
Rugge et al. (2015) [39]	All-cause mortality; 40–70 years	Treated	Untreated	HR 0.36 (0.19–0.66)
	All-cause mortality; >70 years			HR 0.71 (0.56–1.08)
Yang et al. (2019) [50]	All-cause mortality	Untreated	Euthyroid	HR 1.48 (1.29–1.70)
		Treated	Euthyroid	HR 1.48 (1.14–1.94)
Razvi et al. (2008) [46]	IHD/all-cause mortality; <65 years	Untreated	Euthyroid	OR 1.32 (0.95–1.83)
	IHD/all-cause mortality; > 65 years			OR 0.87 (0.51–1.45)
Sun et al. (2017) [43]	Total mortality	Untreated	Euthyroid	RR 1.01 (0.90–1.15)
Singh et al. (2008) [48]	All-cause mortality	Untreated	Euthyroid	RR 1.115 (0.990–1.255)

HR–Hazard Ratio; RR–Relative Risk; IRR–Incident rate Ratio; IHD–Ischemic Heart Disease; OR–Odds Ratio.