Does adjunctive CytoSorb therapy improve inflammatory indices in crush syndrome patients receiving continuous renal replacement therapy? A retrospective cohort study

Cytokine adsorption therapy has gained increasing interest as an adjunct to continuous renal replacement therapy (CRRT) in critically ill patients with excessive systemic inflammation. However, whether its addition to CRRT effectively reduces systemic inflammatory burden remains unclear. Complete blood count (CBC) - derived inflammatory indices may provide practical information on the magnitude of systemic inflammation when direct cytokine measurements are not readily available. This study aimed to investigate whether the addition of a cytokine-adsorbing filter to CRRT was associated with measurable differences in CBC-derived inflammatory indices among patients with crush syndrome following the February 6, 2023, Kahramanmaraş earthquakes. This retrospective cohort study included 22 adult patients with crush syndrome treated at a tertiary trauma center following the February 6, 2023, Kahramanmaraş earthquakes. Patients were categorized into three groups: CRRT alone (n = 8), CRRT with cytokine adsorption membrane (n = 10), and no CRRT (n = 4). Blood cell derived inflammatory indices including; neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune–inflammation index, systemic inflammation response index, aggregate index of systemic inflammation, and C-reactive protein-to-albumin ratio, were calculated as baseline (Day 0) and 72 h later (Day 3). Day 3 values and changes from Day 0 to Day 3 were compared among the groups using the Kruskal–Wallis test. For PLR, CRP, and absolute blood cell counts, analyses of covariance were additionally performed to compare Day 3 values among the groups after adjustment for the corresponding baseline values, where model assumptions were satisfied. No statistically significant differences were observed among the groups in the selected baseline demographic, clinical, and laboratory variables. Among the investigated inflammatory indices, only Day 3 PLR and its absolute 72-hour change differed significantly among the groups. After adjustment for baseline PLR, Day 3 PLR remained significantly different among the treatment groups (F(2,17) = 11.189, p < 0.001, partial η²=0.568). Bonferroni-adjusted comparisons showed lower adjusted Day 3 PLR in the CRRT plus CytoSorb group than in the CRRT-only group (p = 0.017) and the no-CRRT group (p = 0.001), whereas the CRRT-only and no-CRRT groups did not differ significantly (p = 0.339). No significant between-group differences were observed for the other inflammatory indices. In this small retrospective cohort, adjunctive CytoSorb® hemoadsorption during CRRT was not associated with a consistent additional improvement across most routine laboratory-derived inflammatory indices compared with CRRT alone. However, after adjustment for baseline values, Day 3 PLR was significantly lower in the CRRT plus CytoSorb group than in the CRRT-only group. Given the limited sample size, non-random treatment allocation, indirect nature of PLR, and absence of direct cytokine measurements, this finding should be regarded as exploratory and hypothesis-generating rather than as evidence of a specific cytokine-removal or clinical treatment effect. Among the investigated inflammatory indices, PLR was the only marker showing a significant between-group difference at 72 h. After adjustment for baseline PLR, Day 3 PLR was significantly lower in the CRRT plus CytoSorb® group than in the CRRT-only group. Most other routine laboratory-derived inflammatory indices did not show a consistent additional improvement with adjunctive CytoSorb therapy. The PLR finding should be regarded as exploratory and hypothesis-generating because of the small sample size, non-random treatment allocation, and absence of direct cytokine measurement.