The prognostic value of blood cellular indices in pulmonary embolism

Prognostication in acute pulmonary embolism (PE) requires reliable markers. While cellular indices such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) appear promising, their utility in PE prognostication needs further exploration. We utilized data from the RIETE registry and the Loyola University Medical Center (LUMC) to assess the prognostic value of NLR, PLR, and SII in acute PE, using logistic regression models. The primary outcome was 30-day all-cause mortality. We compared their prognostic value versus the simplified Pulmonary Embolism Severity Index (sPESI) alone. We included 10 085 patients from RIETE and 700 from the LUMC. Thirty-day mortality rates were 4.6% and 8.3%, respectively. On multivariable analysis, an elevated NLR (>7.0) was associated with increased mortality (adjusted odds ratio [aOR]: 3.46; 95% CI: 2.60-4.60), outperforming the PLR > 220 (aOR: 2.36; 95% CI: 1.77-3.13), and SII > 1600 (aOR: 2.52; 95% CI: 1.90-3.33). The c-statistic for NLR in patients with low-risk PE was 0.78 (95% CI: 0.69-0.86). Respective numbers were 0.66 (95% CI: 0.63-0.69) and 0.68 (95% CI: 0.59-0.76) for intermediate-risk and high-risk patients. These findings were mirrored in the LUMC cohort. Among 9810 normotensive patients in RIETE, those scoring 0 points in sPESI and with an NLR ≤ 7.0 (35% of the population) displayed superior sensitivity (97.1%; 95% CI: 95.5-98.7) and negative predictive value (99.7%; 95% CI: 99.5-99.8) than sPESI alone (87.1%; 95% CI: 83.9-90.3, and 98.7%; 95% CI: 98.4-99.1, respectively) for 30-day mortality. The NLR is a significant prognostic marker for 30-day mortality in PE patients, especially useful to identify patients with very low-risk PE.