是这么理解的吗？

Preoperative measurement of biomarkers remains an emerging area of investigation for perioperative risk assessment. Serum levels of B-type natriuretic peptide (BNP), a polypeptide released by cardiomyocytes in response to atrial stretch, or the N-terminal pro-BNP (NT-ProBNP) may be associated with perioperative cardiovascular risk. Based on a meta-analysis of individual patient data from 18 prospective observational studies, preoperative BNP levels greater than 92 pg/mL or NT-ProBNP levels greater than 300 pg/mL were associated with increased risk of death or myocardial infarction at 30 days (21.8% in patients with BNP levels >92 pg/mL or NTProBNP levels >300 pg/mL vs 4.9% in patients with natriuretic peptides below these levels). Preoperative natriuretic peptide levels were also associated with improved performance of a risk model that included age, Revised Cardiac Risk Index of 3 or greater, vascular surgery, and urgent surgery for the outcome of 30-day perioperative cardiovascular risk, with a net reclassification index of 18%.

术前测量生物标记物仍然是围手术期风险评估的一个新兴研究领域。血清B型利钠肽（BNP）或N端pro-BNP（NT-ProBNP）水平可能与围手术期心血管风险相关。基于18项前瞻性观察性研究的个体患者数据的荟萃分析，病人术前BNP水平大于92 pg/mL或NT-ProBNP水平大于300 pg/mL与30天死亡或心肌梗死的风险增加有关（BNP水平> 92 pg / mL或NT- ProBNP水平> 300 pg / mL的患者中30天死亡或心肌梗死为21.8%，利钠肽低于这一水平的患者30天死亡或心肌梗死率只有4.9%的）。术前利钠肽水平也与风险模型的改善有关，其中包括年龄、修订的心脏风险指数为3或3以上、血管手术和紧急手术对围手术期30天心血管风险的结果，净重分指数为18%。

翻译的对吗？哪位老师能不能再讲讲净重分指数？谢谢