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

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.