Table 2. The results of meta-regression.

Sources	Coefficient (95% CI)	t	P	Adjusted R2 (%)
Speciman type	–2.82 (–6.29-0.64)	–1.93	0.096	58.78
Age	0.61 (0.01-1.20)	2.42	0.046	100.00

CI, confidence interval.