highly significantp < 0.0001
The quadratic term for age (Age 2 ) was highly significant (β = 0.0021, SE = 0.0002, 95% CI [0.0018, 0.0025], p < 0.0001), accounting for 77.7% of heterogeneity, which indicates a non-linear effect across the age range (∼42–70 years).