Telomere Length And Health Outcomes: Of 50 possible outcomes studied, only important for gastric cancer and, probably, diabetes and Alzheimer's disease

Telomere Length And Health Outcomes: An umbrella review of systematic reviews and meta-analyses of observational studies. Lee Smith et al. Ageing Research Reviews, https://doi.org/10.1016/j.arr.2019.02.003

Highlights
• Shorter telomere length are associated with higher risk of non-communicable disease.

• Until now no attempt has been made to capture the breadth of outcomes associated with telomere length.

• This review indicates that shorter telomere length has a highly suggestive association with incidence of only specific cancer types, and has suggestive evidence with diabetes and Alzheimer’s disease risks.

• Telomere length has a weak association with heightened risks in a range of other important health outcomes (n = 20), whereas it has no role with others, including 27 outcomes out of 50.


Abstract: The aim of the present study was to map and grade evidence for the relationships between telomere length with a diverse range of health outcomes, using an umbrella review of systematic reviews with meta-analyses. We searched for meta-analyses of observational studies reporting on the association of telomere length with any health outcome (clinical disease outcomes and intermediate traits). For each association, random-effects summary effect size, 95% confidence interval (CI), and 95% prediction interval were calculated. To evaluate the credibility of the identified evidence, we assessed also heterogeneity, evidence for small-study effect and evidence for excess significance bias. Twenty-one relevant meta-analyses were identified reporting on 50 different outcomes and including a total of 326 observational studies. The level of evidence was high only for the association of short telomeres with higher risk of gastric cancer in the general population (relative risk, RR = 1.95, 95%CI: 1.68-2.26), and moderate for the association of shorter telomeres with diabetes or with Alzheimer’s disease, even if limited to meta-analyses of case-control studies. There was weak evidence for twenty outcomes and not significant association for 27 health outcomes. The present umbrella review demonstrates that shorter telomere length may have an important role in incidence gastric cancer and, probably, diabetes and Alzheimer’s disease. At the same time, conversely to general assumptions, it does not find strong evidence supporting the notion that shorter telomere length plays an important role in many health outcomes that have been studied thus far.

Keywords: Telomere lengthumbrella reviewobservational studies

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Some of the outcomes studied:

Disease-free survival in chronic lymphocytic leukemia
Esophageal cancer
Head and neck cancer
Overall survival in glioma
Overall survival in lung cancer
Prostate cancer
Skin cancer - basal cell carcinoma
Skin cancer - melanoma
Depression
Stroke
Myocardial Infarction
type II diabetes mellitus
coronary heart disease
All-cause mortality in breast cancer
Bladder cancer
Breast cancer
Cancer recurrence
in breast cancer
Cancerspecific mortality in breast cancer
Colorectal cancer
Disease-free survival in colorectal cancer
Hepatocellular carcinoma
Lung cancer
Lymphoma - Hodgkin's lymphoma
Ovarian cancer
Overall survival in bladder cancer
Overall survival in chronic lymphocytic leukemia
Overall survival in colorectal cancer
Overall survival in esophageal cancer
Overall survival in ovarian cancer
Progressionfree survival in lung cancer
Renal cell carcinoma
AF  (incident)