A new review looked at how two blood markers—neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII)—might predict lung problems after surgery. The study combined data from nearly 4,000 adults who had lung or esophagus removal surgery. The main goal was to see if higher levels of these markers before surgery were linked to pneumonia or other pulmonary complications.
The results showed that higher NLR was linked to about a twofold increase in risk for each unit increase, and about a fourfold increase when compared to specific thresholds. Higher SII also showed a similar pattern of increased risk. However, the evidence came from only a few small studies, and the overall certainty was low.
Because the studies were small and mostly looked back at past data, the findings are not strong enough to guide doctor decisions yet. The markers are low-cost and easy to measure, so they could be useful in the future. More research with larger groups and better methods is needed to confirm these results.
In short, these blood markers might help doctors guess who is at higher risk after surgery, but they should not be used for routine care until more proof is available.