Abdominal Visceral Adipose Tissue and All-Cause Mortality: A Systematic Review
Randa K Saad1,2, Malak Ghezzawi2, Renee Horanieh2
1Calcium Metabolism and Osteoporosis Program, World Health Organization (WHO) Collaborating Center for Metabolic Bone Disorders, Division of Endocrinology and Metabolism, Department of Internal Medicine - American University of Beirut Medical Center, Beirut, Lebanon.
Insights
High abdominal visceral adipose tissue (VAT) area is linked to increased mortality risk in younger adults, but this association weakens or reverses in older individuals. Further research is needed to confirm these findings.
Area of Science:
- Cardiology
- Metabolic Health
- Epidemiology
Background:
- Increased abdominal visceral adipose tissue (VAT) is linked to adverse cardio-metabolic profiles.
- The association between VAT parameters and all-cause mortality requires further investigation.
Approach:
- Systematic literature search across four databases.
- Inclusion of 12 cohorts, with most using computed tomography for VAT assessment.
- Duplicate and independent data abstraction and quality assessment.
Key Points:
- In individuals ≤ 65 years, higher VAT area/volume correlated with increased mortality risk (11-98% RR increase).
- This association lost significance after adjusting for metabolic factors (glycemic indices, BMI).
- In older cohorts (>65 years), findings were inconsistent; higher VAT density was linked to increased mortality.
Conclusions:
- Abdominal VAT area may increase mortality risk in younger individuals, likely mediated by metabolic complications.
- The relationship is weaker and potentially reversed in older adults due to confounding and reverse causality.
- An individual participant data meta-analysis is recommended to establish definitive VAT area cutoffs for mortality risk.
Introduction:
Increased abdominal visceral adipose tissue (VAT) implies an adverse cardio-metabolic profile. We examined the association of abdominal VAT parameters and all-cause mortality risk.
Methods:
We systematically searched four databases. We performed citations/articles screening, data abstraction, and quality assessment in duplicate and independently (CRD42020205021).
Results:
We included 12 cohorts, the majority used computed tomography to assess abdominal VAT area. Six cohorts with a mean age ≤ 65 years, examining all-cause mortality risk per increment in VAT area (cm2) or volume (cm3), showed a 11-98% relative risk increase with higher VAT parameters. However, the association lost significance after adjusting for glycemic indices, body mass index, or other fat parameters. In 4 cohorts with a mean age >65 years, the findings on mortality were inconsistent. Conversely, in two cohorts (mean age 73-77 years), a higher VAT density, was inversely proportional to VAT area, and implied a higher mortality risk.
Conclusion:
A high abdominal VAT area seems to be associated with increased all-cause mortality in individuals ≤ 65 years, possibly mediated by metabolic complications, and not through an independent effect. This relationship is weaker and may reverse in older individuals, most likely secondary to confounding bias and reverse causality. An individual participant data meta-analysis is needed to confirm our findings, and to define an abdominal VAT area cutoff implying increased mortality risk.
Systematic Review Registration:
https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=205021, identifier CRD42020205021.
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