Hyperhomocysteinemia and its association with decreased glomerular filtration rate in patients with chronic kidney disease: a comprehensive meta-analysis.

However, there was a highly significant heterogeneity among studies ( P < 0.01, I 2 = 99.5%), meaning that 99.5% of the variation in effect sizes is attributed to differences in study features, populations, or methodologies rather than sampling error ( Fig. 2 ).

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