Pretreatment NLR reflected distinct inflammatory phenotypes and was independently associated with infection-related mortality in patients with newly diagnosed MPA, so it may have potential as a prognostic biomarker, although further validation is required.
Higher pretreatment NLR was associated with greater baseline disease severity in newly diagnosed MPA.
Organ involvement differed by NLR: diffuse alveolar haemorrhage was more frequent with higher NLR, while interstitial lung disease was more common with lower NLR.
Patients with higher pretreatment NLR received more intensive remission-induction therapy.
After treatment initiation, disease activity, glucocorticoid tapering, and cumulative organ damage became comparable across NLR groups despite baseline differences.
Pretreatment NLR was not associated with relapse-free survival.
Higher pretreatment NLR was associated with poorer overall survival and higher infection-related mortality in unadjusted analyses.
After stabilised inverse probability weighting, the association with overall survival was no longer significant, but the increased risk of infection-related mortality remained significant.
The authors conclude that pretreatment NLR, an inexpensive and widely available marker, may be a prognostic biomarker for infection-related mortality in MPA, pending validation.
This study looked at whether a simple, cheap blood test ratio, called the neutrophil-to-lymphocyte ratio (NLR), measured before treatment could tell doctors something about the course of microscopic polyangiitis (MPA). MPA is a rare inflammatory disease of small blood vessels that can damage the kidneys and lungs. The researchers analysed 340 newly diagnosed, previously untreated patients from a multicentre Japanese cohort and divided them into three groups by NLR. Patients with higher NLR had more active and severe disease at diagnosis, including worse kidney function and more bleeding in the lungs, and they received more intensive treatment. Patients with lower NLR were more likely to have interstitial lung disease (scarring of the lungs). Once treatment began, disease activity, steroid tapering, and accumulated organ damage looked similar across groups, and relapse rates did not differ. However, higher NLR was linked to a higher risk of death from infection, and this link held up (hazard ratio 3.47) even after statistical adjustment for differences between groups. This research suggests that NLR might help identify patients with MPA at higher risk of fatal infection, using a test that is already widely available. The authors caution that this is an observational study and that the findings need to be validated before NLR can be used in clinical practice.
Hatta M, Watanabe R, Shiomi M, Masuda Y, Okazaki A, Matsuda S, et al.. (2026). Pretreatment neutrophil-to-lymphocyte ratio is associated with clinical phenotypes and infection-related mortality in microscopic polyangiitis: the multicentre REVEAL cohort study.. Frontiers in immunology. https://doi.org/10.3389/fimmu.2026.1948318