Splenic volume in pneumococcal pneumonia patients is associated with disease severity and mortality.

Splenectomy is a risk factor for serious pneumococcal disease like overwhelming post-splenectomy infection (OPSI). In healthy individuals with small spleen, fulminant pneumococcal infection similar to OPSI has been reported. Furthermore, it is reported that small spleen was associated with severe pneumococcal infection patients treated in an intensive care unit. However, the association between the small spleen and pneumococcal pneumonia was not investigated enough. We retrospectively analyzed patients with pneumococcal pneumonia who underwent computed tomography examination with measurement of the splenic volume at Harasanshin Hospital between 2004 and 2019. Data on their background characteristics, laboratory findings, and clinical courses were collected. 413 patients were included in the final analysis. The splenic volume was significantly lower in the moderate (P < 0.001), severe (P < 0.00005), and extremely severe (P < 0.001) pneumonia groups compared with the mild pneumonia group. Furthermore, the splenic volume was significantly lower in patients died within 30 days of pneumonia treatment (median of 73.49 versus 110.77 cm3, P < 0.005) or during hospitalization (median of 71.69 versus 111.01 cm3, P < 0.0005). Splenic volume <40 cm3 was significantly associated with mortality within 30 days and total hospital mortality as a risk factor in univariate analysis. Splenic volume <40 cm3 was an independent risk factor for mortality within 30 days (odds ratio: 5.0, 95% confidence interval: 1.2-21.1, P < 0.05) and total hospital mortality (odds ratio: 7.4, 95% confidence interval: 1.8-30.6, P < 0.01) in multivariate logistic regression analysis. These results suggest that small spleen is a risk factor for severity and mortality of pneumococcal pneumonia.