Pneumococcal vaccine coverage in Japan among patients with a history of splenectomy: Results of a retrospective administrative database study

Abstract

Background: Splenectomy results in immune deficiency and increases the risk of clinically significant infections, termed overwhelming post-splenectomy infection (OPSI). In Japan, vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) is covered by the Japanese National Health Insurance (NHI) for post-splenectomy patients, but there are limited data about whether these patients receive PPSV23 vaccination. Methods: We performed retrospective analyses of the JMDC Claims Database comprising employees (including some retired individuals) and their families in Japan. We identified patients who underwent splenectomy (registration period: January 1, 2005–June 30, 2019) at ≥ 2 to ≤ 64 years old, and obtained information about PPSV23 vaccination, reasons for splenectomy, and prevalence/complications of pneumococcal infectious diseases (including OPSI-related disorders). Results: Among 7,394,182 registered individuals, splenectomy was performed in 475, with an incidence rate of 1.6 cases per 100,000 person-years. Of 414 patients who underwent splenectomy at ≥ 2 to ≤ 64 years of age, their mean ± standard deviation age was 45.4 ± 15.7 years and 63.3% were 45–64 years old. Splenectomy was incidental in 55.3%. Overall, 123/414 patients were prescribed PPSV23 vaccination, resulting in vaccination coverage of 29.7%. The median interval from splenectomy to vaccination was 1.0 month (range: –1 to 85 months). Conclusion: This was the first study to document PPSV23 vaccination coverage after splenectomy in a Japanese real-world setting. PPSV23 coverage is quite low in Japan relative to that in other countries.