Table 2.

Meta-regression examining the moderation effects of biological and methodological factors on the corrected correlation between telomere length and chronological age in cross-sectional samples excluding the two influential cases.

Moderator	Number of study samples	β estimate	95% CI	P value
Age center	284	0.003	0.002 to 0.005	<0.001***
Age group
Children (<18 years)	21	Reference
Adults (≥18 years)	212	0.337	0.204 to 0.471	<0.001***
Sex †
Only male	37	Reference
Only female	39	0.023	−0.098 to 0.144	0.711
Both males and females	199	−0.003	−0.109 to 0.102	0.950
Health status ‡
Healthy	120	Reference
General population	92	−0.095	−0.181 to −0.009	0.031*
CVDs	24	0.010	−0.119 to 0.138	0.883
Cancer	36	0.009	−0.123 to 0.140	0.897
Depression/Anxiety/PTSD	12	0.044	−0.130 to 0.219	0.620
TL measurement method ‡
Southern blot	56	Reference
qPCR	214	0.030	−0.072 to 0.132	0.559
qFISH	9	−0.280	−0.557 to −0.004	0.047*
Flow FISH	5	−0.135	−0.429 to 0.159	0.367
Tissue type ‡
Blood leukocytes	221	Reference
Dry blood spots	4	−0.280	−0.557 to −0.004	0.047*
PBMCs	37	0.055	−0.059 to 0.169	0.343
Saliva	13	0.151	−0.025 to 0.327	0.093
Buccal cells	9	−0.204	−0.406 to −0.001	0.049*
DNA extraction procedure‡
Salting out	59	Reference
Silica membrane column	76	0.065	−0.065 to 0.194	0.324
Magnetic bead	12	0.129	−0.104 to 0.362	0.275
Phenol-chloroform	14	0.086	−0.157 to 0.330	0.485
Anion exchange	1	0.161	−0.480 to 0.801	0.621

CVD, cardiovascular disease; PTSD, post-traumatic stress disorder; qPCR, quantitative polymerase chain reaction; qFISH, quantitative fluorescence in situ hybridization; PBMC, peripheral blood mononuclear cells; CI, confidence interval. Correlations were corrected for the age range restriction to reduce the noise caused by the heterogeneity of age range across different samples.

^†Meta-regression models were controlled for age center.

^‡Meta-regression models were controlled for age center and sex.

^*p < 0.05

^**p < 0.01

^***p < 0.001