Epidemiology and Clinical Outcomes of Meningococcal Infections in Japan: A Nationwide Inpatient Database Study From...

Meningococcal infection remains a life-threatening disease despite advances in early recognition and therapy. While the incidence of meningococcal infection is extremely low in Japan, nationwide data on its clinical outcomes have been lacking.

We conducted a retrospective cohort study using the Japanese Diagnosis Procedure Combination (DPC) inpatient database from July 2010 to March 2023. Patients with a main diagnosis of meningococcal infection (International Classification of Diseases, 10^th Revision code A39) were included. The primary outcome was in-hospital mortality. Secondary outcomes included impaired consciousness at discharge and functional status, assessed using the Barthel Index. Multivariable logistic regression was performed to identify prognostic factors.

A total of 465 patients were analyzed. The median age was 55 years, and 57.0% were male. The in-hospital mortality rate was 8.2%, and 40.2% of survivors had a Barthel Index ≤90 at discharge. Early antibiotic administration did not significantly reduce mortality but was associated with improved neurological outcomes. Baseline impaired consciousness was the strongest predictor of mortality and poor functional status, while chronic comorbidities also contributed to worse outcomes. Notably, older age itself was not independently associated with mortality after adjustment for severity and comorbidities.

Meningococcal infection outcomes in Japan are predominantly determined by the severity of illness at presentation and comorbid health conditions rather than age alone. Early antibiotic therapy improves neurological recovery but may not prevent death once critical illness is established. These findings underscore the importance of prevention through vaccination and early recognition strategies to reduce the burden of this devastating infection.