Inflammation Indıces and Mortality in Adult Crush Syndrome

Crush syndrome is a life-threatening consequence of traumatic rhabdomyolysis, characterized by a systemic inflammatory response, acute kidney injury, electrolyte disturbances, and multi-organ dysfunction, with the highest mortality observed among patients requiring intensive care. Early and objective risk stratification is essential for guiding fluid resuscitation, informing the timing of renal replacement therapy, and allocating critical care resources.

In this single-center, retrospective cohort study, adult patients (≥18 years) diagnosed with crush syndrome and admitted to the intensive care unit of Ataturk University Research Hospital between January 1, 2018, and September 30, 2025, were identified from the hospital electronic health information system. The diagnosis was based on a compatible history of crush injury together with a serum creatine kinase level exceeding five times the upper limit of normal. Patients with conditions that directly alter hematological indices - hematological malignancy, active chemotherapy, chronic immunosuppressive therapy, massive transfusion within the first 24 hours, or known thrombocytopenia - were excluded. Demographic data, complete blood count parameters, and disease-severity scores were retrieved from electronic medical records.

The following inflammatory indices were calculated from the complete blood count obtained within the first 24 hours of ICU admission: NLR (neutrophils/lymphocytes), PLR (platelets/lymphocytes), MLR (monocytes/lymphocytes), SII (platelets × neutrophils/lymphocytes), SIRI (neutrophils × monocytes/lymphocytes), and PIV (neutrophils × platelets × monocytes/lymphocytes).

The primary and only endpoint was 28-day mortality following ICU admission. Group comparisons were performed using the Mann-Whitney U and Student t tests. Discrimination for 28-day mortality was assessed by receiver operating characteristic (ROC) curve analysis, and the areas under the curve were compared with the DeLong test. Because the six indices are deterministic ratios of four blood-count components and are therefore highly collinear, each index was entered into a separate logistic regression model together with the APACHE II and SOFA scores, rather than including all indices in a single model. The incremental discriminatory value of each index beyond an APACHE II plus SOFA base model was quantified as the change in the area under the curve, and internal validity was examined by bootstrapping. The study aimed to determine whether these readily available hematological indices provide prognostic value beyond established severity scores in critically ill patients with crush syndrome.

Inclusion criteria

• Age ≥18 years
• Diagnosis of crush syndrome based on clinical and laboratory findings
• Admission to the intensive care unit (ICU) between January 1, 2018 and September 30, 2025
• Availability of complete blood count parameters within the first 24 hours of ICU admission

Exclusion criteria

• Age <18 years
• Incomplete medical records
• Missing laboratory data required for calculation of inflammatory indices
• Patients discharged or transferred within 24 hours of ICU admission