Can neutrophil/lymphocyte ratio, C-reactive protein (CRP) and procalcitonin predict the hospitalization time in patients with lower tract respiratory infections?

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Introduction Lower respiratory tract infections (LTRI) are important hospitalization cause in pulmonary wards. The hospitalization time directly affects hospitalization costs. We aimed to find out whether the blood neutrophil/lymphocyte ratio (NLR), C-reactive protein (CRP) and procalcitonin (PCT) values predict the hospitalization time in patients with LTRI. Material and methods We evaluated patients retrospectively between January 2016 and December 2018 in a cross-sectional study. 1297 patients with the diagnosis of pneumonia, chronic obstructive pulmonary disease (COPD) exacerbation, bronchiectasis exacerbation, parapneumonic effusions, and empyema were included in the study according to ICD-10 and hospitalization criteria guidelines. Results Of 1297 patients, 762 (58.75%) were male and median age was 63 (interquartile range (IQR): 55–75). Median hospitalization time was 7 (IQR: 5–10) days. Median NLR was 6.28 (3.78–10.92), median CRP was 79.2 (IQR: 26.7–171.5) mg/l and median PCT was 0.23 (IQR: 0.08–0.51) ng/ml. Over 7 days’ hospitalization time was accepted as long-term hospitalization time. Median NLR was 5.73 (IQR: 5.51–10.16) in < 7 days, 6.94 (IQR: 4.22–11.77) in > 7 days. The difference was statistically significant between the groups (p = 0.000). Median CRP value was 61.5 (IQR: 21.75–139.70) mg/l in ≤ 7 days, and 109.4 (IQR: 22.4–199.5) mg/l in > 7 days. The difference was significant between the groups (p < 0.001). Median PCT value was 0.20 (IQR: 0.07–0.45) mg/l ≤ 7 in days and 0.28 (IQR: 0.10–0.55) mg/l in > 7 days. The difference was not significant between the groups (p = 0.055). For the multivariate analysis, the possible factors identified with univariate analyses were further entered into a logistic regression analysis to determine independent predictors of long-term hospitalization. The odds ratio for CRP was OR = 0.004 (p < 0.001), but NLR and PCT was not significant (p = 0.777, p = 0.784, respectively). Sputum culture positivity and radiological infiltration were associated with the long-term hospitalization (p = 0.003 and p = 0.027, respectively). Conclusions CRP value was associated with the long-term hospitalization in patients with LTRI, but not with NLR and PCT. Sputum culture positivity and radiological infiltration might affect the long-term hospitalization.