Background : Splenectomy is an essential surgical procedure for various indications, but its long-term effects on mortality remain unclear. This study aims to evaluate these impacts to enhance patient outcomes.

Methods : A total of 4,625,294 individuals aged ≥ 20 years who underwent health examinations in 2012 were identified using the Korean National Health Insurance Service database. After exclusions, 985 splenectomy patients were compared with 4,624,309 controls. Mortality outcomes were assessed over a mean follow-up of 9.19 years using Cox proportional hazards models adjusted for demographic and clinical variables.

Results : Splenectomy was associated with a significant increase in all-cause mortality (HR = 1.732, 95% CI: 1.511–1.985), leading to elevated risks of cancer-related (HR = 1.824, 95% CI: 1.495–2.226), cardiovascular (HR = 1.754, 95% CI: 1.210–2.542), and trauma-related mortality (HR = 2.439, 95% CI: 1.554–3.827). Infection-related mortality showed no significant increase. Mortality was higher for cancer (HR = 1.800, 95% CI: 1.516–2.136) and non-trauma cases (HR = 1.621, 95% CI: 1.258–2.087), while trauma cases showed no significant increase. Subgroup analysis revealed higher trauma-related mortality for patients with hematologic disorders or benign splenic tumors (HR = 5.498, 95% CI: 2.063–14.651), with no significant increase in cancer-related or cardiovascular mortality in this subgroup. Mortality risks were higher in middle-aged individuals and women (P<0.001 and 0.008, respectively), peaking in the 40-64 age group (HR = 3.071, 95% CI: 2.466–3.825).

Conclusions : Splenectomy significantly increases long-term mortality, particularly from malignancies, cardiovascular events, and trauma. These findings emphasize the need for tailored postoperative management and preventive strategies to reduce these risks.