To the Editor Marcusa et al¹ have examined the influence of baseline low-density lipoprotein cholesterol (LDL-C) levels on percentage LDL-C reduction with statins, ezetimibe, and PCSK9 inhibition. Using this mode of calculation, they report a higher percentage reduction in LDL-C with evolocumab in patients with lower baseline LDL-C levels, compared with a less marked percentage LDL-C reduction with simvastatin at lower baseline LDL-C levels and no significant reduction of LDL-C levels with ezetimibe at lower baseline values.¹ However, the use of percentage changes might be misleading since it is influenced by absolute baseline values, eg, a 30% reduction from 100 mg/dL (to convert to millimoles per liter, multiply by 0.0259) converts to 70 mg/dL, a 30 mg/dL absolute reduction, whereas a 30% reduction from 70 mg/dL converts to 49 mg/dL, a 21 mg/dL absolute reduction. More importantly, assessing the change of a parameter as a function of its baseline value is subject to bias because baseline values are used to calculate percentage changes.^2,3 An analysis of the slope and intercept of the regression lines between LDL-C levels under treatment and baseline LDL-C levels using both linear and log scales, as promoted by MacGregor et al,² seems more appropriate and might yield different results. This mode of analysis and of graphical display would allow a better comparison of evolocumab, simvastatin, and ezetimibe.

致编辑Marcusa 等人¹研究了他汀类药物、依折麦布和 PCSK9 抑制作用对基线低密度脂蛋白胆固醇 (LDL-C) 水平对 LDL-C 降低百分比的影响。使用这种计算模式，他们报告说，在基线 LDL-C 水平较低的患者中，evolocumab 降低 LDL-C 的百分比更高，而在基线 LDL-C 水平较低的情况下，辛伐他汀降低 LDL-C 的百分比不太显着，且没有显着差异。依折麦布可将 LDL-C 水平降低至较低的基线值。 ¹然而，使用百分比变化可能会产生误导，因为它受到绝对基线值的影响，例如，从 100 mg/dL（转换为毫摩尔每升，乘以 0.0259）减少 30% 转换为 70 mg/dL，绝对减少 30 mg/dL，而从 70 mg/dL 减少 30% 转换为 49 mg/dL，绝对减少 21 mg/dL。更重要的是，将参数的变化评估为其基线值的函数会存在偏差，因为基线值用于计算百分比变化。 ^{2 ,3}正如 MacGregor 等人所提倡的，使用线性和对数尺度对治疗下 LDL-C 水平与基线 LDL-C 水平之间的回归线的斜率和截距进行分析， ²似乎更合适，并且可能会产生不同的结果。这种分析和图形显示模式可以更好地比较 evolocumab、辛伐他汀和依折麦布。