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. Author manuscript; available in PMC: 2024 Sep 1.
Published in final edited form as: Ageing Res Rev. 2023 Aug 9;90:102031. doi: 10.1016/j.arr.2023.102031

Table 1.

Descriptive statistics of all the study samples.

Study design Cross-
sectional
Cross-
sectional
Longitudinal Longitudinal
Available statistics Correlation
available
Corrected
correlation
available
TL yearly
change rate
available
TL yearly z-score change
rate available
Number of study samples 341 286 73 49
Number of subjects 720,078 626,744 22,941 20,276
Number of males 335,093 293,070 10,820 9,743
Number of females 383,418 333,168 11,560 10,529
Age range (years) 0-112 0-112 0-97 0-94
Follow-up duration (years) / / 7 (1-41) 6 (1-41)
Sex included
Only males 43 (12.6%) 38 (13.3%) 17 (23.3%) 9 (18.4%)
Only females 48 (14.1%) 39 (13.6%) 16 (21.9%) 8 (16.3%)
Both males and females 233 (68.3%) 200 (69.9%) 38 (52.0%) 31 (63.3%)
Not reported 17 (5.0%) 9 (3.2%) 2 (2.7%) 1 (2.0%)
Health status
Healthy 141 (41.4%) 121 (42.3%) 16 (21.9%) 12 (24.5%)
General population 112 (32.8%) 93 (32.5%) 53 (72.6%) 33 (67.4%)
CVDs 25 (7.3%) 24 (8.4%) 1 (1.4%) 1 (2.0%)
Cancer 51 (15.0%) 36 (12.6%) 1 (1.4%) 1 (2.0%)
Depression/Anxiety/PTSD 12 (3.5%) 12 (4.2%) 2 (2.7%) 2 (4.1%)
TL measurement method
Southern blot 76 (22.3%) 56 (19.6%) 23 (31.5%) 11 (22.4%)
qPCR 248 (72.7%) 216 (75.5%) 50 (68.5%) 38 (77.6%)
qFISH 12 (3.5%) 9 (3.2%) 0 (0%) 0 (0%)
Flow FISH 5 (1.5%) 5 (1.8%) 0 (0%) 0 (0%)
Tissue type used for TL measurement
Blood leukocytes 262 (76.8%) 222 (77.6%) 47 (64.4%) 38 (77.6%)
Dry blood spots 4 (1.2%) 4 (1.4%) 2 (2.7%) 0 (0%)
PBMCs 50 (14.7%) 37 (12.9%) 16 (21.9%) 3 (6.1%)
Saliva 14 (4.1%) 14 (4.9%) 7 (9.6%) 7 (14.3%)
Buccal cells 11 (3.2%) 9 (3.2%) 1 (1.4%) 1 (2.0%)
DNA extraction procedure
Salting out 65 (19.1%) 59 (20.6%) 23 (31.5%) 21 (42.9%)
Silica membrane column 90 (26.4%) 76 (26.6%) 32 (43.8%) 12 (24.5%)
Magnetic bead 15 (4.4%) 14 (4.9%) 1 (1.4%) 1 (2.0%)
Phenol-chloroform 18 (5.3%) 14 (4.9%) 1 (1.4%) 1 (2.0%)
Anion exchange 1 (0.3%) 1 (0.4%) 0 (0%) 0 (0%)
Not reported 152 (44.6%) 122 (42.7%) 16 (21.9%) 14 (28.6%)

CVD, cardiovascular disease; PTSD, post-traumatic stress disorder; qPCR, quantitative polymerase chain reaction; qFISH, quantitative fluorescence in situ hybridization; PBMC, peripheral blood mononuclear cells.

Data are presented as number of study samples (percentage)

Data are presented as median (range)