Prediction of the prognosis of patients with bacteremia caused by encapsulated organisms using spleen volume: A retrospective study

Aim The spleen plays an important role in the immune response, and patients with impaired spleen function are at risk of overwhelming post-splenectomy infection. This study investigated whether the spleen volume could predict the prognosis of patients with bacteremia caused by encapsulated organisms. Methods This was a single-center, retrospective observational study at Tokyo Medical University Hospital. Twenty patients with encapsulated bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Capnocytophaga canimorsus) detected in blood culture between January 2017 and July 2020 were included in the study and categorized into two groups: survive and nonsurvive groups. We investigated the association between spleen volume (SV), spleen volume index (SVI), and in-hospital mortality. The SVI was defined as: SVI-H, spleen volume cm(3)/height m; SVI-BW, spleen volume cm(3)/body weight kg; and SVI-A, spleen volume cm(3) x age/100. Results The number of patients in the survive group was 17, and that of the non-survive group was 3. The SV and SVI were smaller in the nonsurvive group than in the survive group (P < 0.05). The calculated the SV cut-off for the prediction of prognosis was 36 cm(3) with a sensitivity of 94.1% and specificity of 66.7% with a positive predictive value of 94.1% and a negative predictive value of 66.7%. Conclusions The SV and SVI could be used to predict the prognosis of bacteremia caused by encapsulated organisms. If the spleen volume as measured by computed tomography is small, more intensive treatment should be considered.