(A1): Vitamin D and calcium versus no intervention. (A2): Funnel plot for heterogeneity. (A3): Vitamin D and calcium versus no intervention, excluding the studies with high heterogeneity. (B1): Vitamin D and calcium versus calcium. (B2): Funnel plot for heterogeneity. (B3): Vitamin D and calcium versus calcium, excluding the studies with high heterogeneity. (C1): Calcium versus no intervention. (C2): Funnel plot for heterogeneity.
Abbreviations: Ca, calcium; CI, confidence interval; OR, odds ratio; Vit D, vitamin D.