Earth's gravity field and prevalence of varicose veins and chronic venous disease: Systematic review

Aim This study examines the influence of Earth's gravity field on the prevalence of varicose veins in geophysical area. Material and Methods We performed a systematic review (OVID and Google Scholar) of studies focusing on prevalence of varicose veins to determine the influence of Earth's gravity field-GRACE GGM05S gravity model-on the disease prevalence. PROSPERO: CRD42021279513. Results 81 studies met inclusion and quality criteria. Areas with stronger gravity have significantly higher prevalence of varicose veins with adjustment for age, gender and body mass index (BMI) (p-values < 0.02). Adjusted for age, prevalence of varicose veins in areas with gravity field +20 mGal and more is 1.37 time higher than in areas with gravity field less than +20 mGal, p-value 0.005 (95% CI: -12.5 to -2.4): mean disease prevalence for gravity field +20 mGal and more-27.5% (mean age, 40.1 years; mean gravity field, +27.1 mGal; 63.9% females, 37 studies, 123,164 participants) vs mean disease prevalence for gravity field less than +20 mGal - 20.1% (mean age, 42.2 years; mean gravity field, +5.7 mGal; 56.8% females, 44 studies, 205,925 participants). Older age is the main risk factor for varicose veins (p-values < 0.005). Female gender and high BMI are insignificantly associated with high prevalence of varicose veins (p-values > 0.4 for gender, p-values > 0.2 for BMI). Conclusion Stronger gravity field is significantly associated with higher prevalence of varicose veins-risk factor. The potential mechanism of this phenomenon is that high gravity field alters systemic venous return, pooling blood and fluid in the peripheral, gravity-dependent regions of the body in upright humans constantly living in the defined geophysical area.