Fig. 3
![Fig. 3](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs42269-023-01046-5/MediaObjects/42269_2023_1046_Fig3_HTML.png)
The pooled correlation coefficient of Friedewald’s and Martin’s LDL-c equation compared to direct measurement in determining levels of LDL-c from matching studies. The pooled correlation between Martin’s LDL-c equation and the direct measurement in determining levels of LDL-c as well as the correlation between the Friedewald’s LDL-c equation and the direct measurement in determining levels of LDL-c. This correlation pooled 12 studies in the analysis. There was a positive correlation between Martin’s LDL-c equation and the direct measurement in determining levels of LDL-c [0.96 (95% CI 0.94–0.98)]. Similarly, Friedewald’s LDL-c equation positively correlated with the direct measurement in determining levels of LDL-c [0.94 (95% CI 0.92–0.96)]. However, there was a stronger positive correlation between Martin’s LDL-c equation and the direct measurement in determining levels of LDL-c compared to Friedewald’s equation and the direct method