ABSTRACT
BACKGROUND AND AIM: Tissue source has been shown to exert a significant effect on the magnitude of associations between telomere length and various health outcomes and exposures. The purpose of the present qualitative review and meta-analysis is to describe and investigate the impact of study design and methodological features on the correlation between telomere lengths measured in different tissues from the same healthy individual. METHODS: This meta-analysis included studies published from 1988 to 2022. Databases searched included PubMed, Embase, and Web of Science and studies were identified using the keywords "telomere length" and "tissues" or "tissue." A total of 220 articles of 7856 initially identified studies met inclusion criteria for qualitative review, of which 55 met inclusion criteria for meta-analysis in R RESULTS: Studies meeting inclusion criteria for meta-analysis tended to have enhanced demographic and methodological reporting relative to studies only included in the qualitative review. A total of 463 pairwise correlations reported for 4324 unique individuals and 102 distinct tissues were extracted from the 55 studies and subject to meta-analysis, resulting in a significant effect size z = 0.66 (p < 0.0001) and meta-correlation coefficient of r = 0.58. Meta-correlations were significantly moderated by sample size and telomere length measurement methodology, with studies of smaller size and those using hybridization-based analyses exhibiting the largest meta-correlation. Tissue source also significantly moderated the meta-correlation, wherein correlations between samples of a different lineage (e.g., blood vs. non-blood) or collection method (e.g., peripheral vs. surgical) were lower than correlations between samples of the same lineage or collection method. CONCLUSION: These results suggest that telomere lengths measured within individuals are generally correlated, but future research should be intentional in selecting a tissue for telomere length measurement that is most biologically relevant to the exposure or outcome investigated and balance this with the feasibility of obtaining the sample in sufficient numbers of individuals.
