Neutrophil count, lymphocyte count and neutrophil-to-lymphocyte ratio in relation to response to adjunctive dexamethasone treatment in community-acquired pneumonia.

Background: It is hypothesised that community-acquired pneumonia (CAP) patients with more severe disease or inflammation might benefit more from adjunctive corticosteroid treatment. Neutrophil count, lymphocyte count and neutrophil-lymphocyte ratio (NLR) have been associated with inflammation and disease severity in CAP. We investigated the interaction between these parameters and adjunctive dexamethasone effects on clinical outcomes in CAP.

Methods: We conducted a post hoc analysis of the randomised placebo-controlled Santeon-CAP trial (n = 401), which showed a positive effect of adjunctive oral dexamethasone on length of stay (LOS) in CAP patients. White blood cell (WBC) count, neutrophil count, NLR (highest tertile vs. lowest two tertiles) and lymphocyte count (lowest tertile vs. highest two tertiles) were examined as potential effect modifiers of treatment with dexamethasone on LOS (primary outcome) and ICU-admission, 30-day mortality and hospital readmission.

Results: WBC differential counts were available for 354 patients. The effect of dexamethasone on LOS was more pronounced in high WBC count, high neutrophil count or high NLR subgroups (difference in median LOS of 2 days versus zero days in the reference subgroups, p for interaction < 0.05). There was no effect modification for the other outcomes. Patients with low WBC and low neutrophil counts did not benefit from dexamethasone, while hospital readmission rate was higher in those treated with dexamethasone (6% vs. 11%).

Conclusions: WBC count and/or neutrophil might be easily available biomarkers to guide selection of CAP patients who are more likely to benefit from adjunctive dexamethasone treatment. Future prospective trials are needed to confirm this predictive potential.