Introduction:
The study aimed to evaluate the potential role of inflammatory markers (neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), platelet to mean platelet volume (PLT/MPV), C-reactive protein (CRP), CRP/albumin) and demographic, clinical and laboratory parameters in predicting mortality in elderly patients.

Material and methods:
A total of 1971 very elderly (age ≥ 80 years) patients hospitalized due to acute respiratory diseases were included in this retrospective cohort study. Data on patients’ demographics, reasons for admission, comorbidities, inflammatory markers on admission, hospitalization unit, length of hospital stay and survivorship status were recorded. A receiver operating characteristics (ROC) curve was plotted to determine performance of inflammatory marker levels for mortality risk. Logistic regression analysis for hospital mortality was used.

Results:
A total of 1971 patients were admitted, in-ward (n = 1470), intensive care unit (ICU, n = 352), or palliative care unit (PCU, n = 149), and mortality rates were 12.7% (n = 250), 4.5% (n = 66), 34.9% (n = 123), 40.9% (n = 61) respectively. ROC analysis for area under curve (AUC) revealed significant cut-off levels for hospital mortality NLR ≥ 7.75 (AUC = 0.79), CRP ≥ 44 (AUC = 0.82); CRP/albumin ≥ 13.5 (AUC = 0.84) each p < 0.001. For ICU mortality, the cut-off values and AUC were significant respectively for NLR ≥ 7.75 (AUC = 0.82), CRP ≥ 60 (AUC = 0.82), APACHE II ≥ 24 (AUC = 0.76), CRP/albumin ≥ 26 (AUC = 0.78), PLT/MPV < 26.2 (AUC = 0.31) (each p < 0.001). Binary logistic regression revealed that age above 90, PCU and ICU admission, acute and chronic renal failure and NLR ≥ 7.75 were significant mortality predictors (odds ratio, 95% CI, p-value: 2.57, 1.05–6.31, 0.039; 77.18, 18.98–313.81, < 0.001; 20.75, 1.96–98.73, < 0.001; 18.99, 1.31–275.31, 0.031; 3.35, 1.06–10.54, 0.039; 7.83, 3.34–18.38, 0.001).

Conclusions:
Very elderly patients with respiratory diseases who are admitted to the ICU or PCU with acute and chronic renal failure requiring ICU admission and with NLR values above 7.75 on admission have very high risk for mortality.