Association between platelet to white blood cell ratio and 28-day mortality in intensive care unit patients with Sepsis: A multicentre validation study using the eICU collaborative research database.

BACKGROUND

Sepsis is a leading intensive care units (ICUs) mortality cause; simple biomarkers for early risk stratification are needed, and the prognostic value of platelet to WBC ratio (PWR) in sepsis lacks large multicentre validation.

OBJECTIVE

We validated PWR's association with 28-day mortality in ICU sepsis patients via eICU data and explored its incremental value with severity scores.

METHODS

This retrospective cohort study utilised the eICU Collaborative Research Database (2014-2015), which contains data from 335 ICUs across 208 US hospitals. Adult patients meeting the Third International Consensus Definitions for Sepsis and Septic Shock criteria were included. The PWR was calculated from laboratory values within 24 h of ICU admission. The primary outcome was 28-day mortality. Multivariable logistic regression and Cox proportional hazards models were employed, adjusting for demographics, comorbidities and severity scores. Platelet to WBC ratio was analysed both as a continuous variable and as a categorical variable based on the optimal cutoff value derived from the Youden index to address non-linearity.

RESULTS

Among 18,745 patients with sepsis, 3934 (21.0%) died within 28 days. Non-survivors had significantly lower PWR (median 15.2 vs 22.8, p < 0.001). Using the optimal cutoff of 18.5, patients with low PWR (≤18.5) had significantly higher 28-day mortality than those with high PWR (>18.5) (adjusted odds ratio: 2.18, 95%CI: 1.98-2.40, p < 0.001). The combination of PWR and Acute Physiology and Chronic Health Evaluation (APACHE) IV score significantly improved mortality prediction (area under the curve: 0.812 vs 0.768 for APACHE IV alone, DeLong test: p < 0.001). Subgroup analyses revealed consistent associations across different sepsis aetiologies and comorbidities.

CONCLUSION

Lower PWR is associated with increased 28-day mortality in ICU patients with sepsis after adjusting for confounders. This simple, readily available biomarker may aid in early risk stratification and clinical decision-making.