Table 2.

Overall summary estimates of effect for the associations between gender and telomere length from stratified random effects meta-analyses.

Stratification	Noa	ESb females–males	95% CI	(Age-adjusted) p-value	I2	p-valuec
None	36	0.090	0.015, 0.166	0.02	91.4%	<0.001
Mean aged (years)
≤55.8	18	0.091	−0.018, 0.200	0.10	92.4%	<0.001
>55.8	18	0.090	−0.021, 0.210	0.11	90.2%	<0.001
					F ratio	p-value
Overalle					0.00	1.00
Measurement method
Real-time PCR	17	−0.047	−0.167, 0.072	0.44	93.2%	<0.001
TRF Southern Blot	17	0.240	0.173, 0.307	<0.001	68.8%	<0.001
Flow-FISH	2	0.077	−0.016, 0.171	0.11	0.0%	0.65
					F ratio	p-value
Overalle					5.72	0.007
Cell Typef
Whole Blood	27	0.132	0.050, 0.215	0.002	91.9%	<0.001
PBMC	6	−0.070	−0.354, 0.215	0.63	87.9%	<0.001
Lymphocytes	1	−0.194	−0.461, 0.072	0.15	–	–
Granulocytes	2	0.077	−0.016, 0.171	0.11	0.0%	0.65
					F ratio	p-value
Overalle					1.31	0.29

^aNumber of studies.

^bStandardised regression coefficient (standardising for telomere length) representing the age-adjusted difference in telomere length between females and males. Here males are the baseline group so that the coefficient represents the difference in telomere length for females and males. Hence if females have longer telomeres this would be positive.

^cp-value is obtained from the heterogeneity χ².

^dStratified by the mean age above and below the median age.

^eOverall test for heterogeneity between subgroups by undertaking meta-regression and giving F ratio and p-values.

^fCell types are whole blood (leukocytes: lymphocytes, monocytes and granulocytes) and Peripheral Blood Mononucleocytes (PBMC: enriched for lymphocytes), lymphocytes or granulocytes. Random effects meta-analyses were used throughout.