A Link Between Immunoglobulin M Levels and Overwhelming Post-Splenectomy Infection Risk in a National Asplenia Cohort.

BACKGROUND

Overwhelming post-splenectomy infection (OPSI) is a rare complication of asplenia that is frequently fatal. OPSI risk remains elevated in patients with asplenia who receive the Advisory Committee on Immunization Practices (ACIP)-recommended vaccines, suggesting additional variables influence OPSI risk.

OBJECTIVE

To identify clinical and immunologic factors associated with OPSI in individuals with anatomic or functional asplenia.

METHODS

A retrospective cohort study was conducted of 2,992 individuals with physician-confirmed anatomic or functional asplenia and identified 47 OPSI cases. Demographic, clinical, and laboratory variables were analyzed to identify independent risk factors for OPSI. Receiver operating characteristic (ROC) analysis assessed predictive values of immunoglobulin levels, and time from asplenia index date to OPSI was summarized among cases.

RESULTS

Streptococcus pneumoniae accounted for 89% of OPSI episodes. Prior to OPSI, most patients had documented receipt of asplenia-targeted vaccines corresponding to the bacterial species causing their specific infections. IgM <61.5 mg/dL was present in 86.7% (39/45) and 15.0% (164/1093) of patients with and without OPSI, respectively (p<0.001). In adjusted analysis, IgM <61.5 mg/dL (aOR 26.05 [9.28-73.13], p<0.001) was associated with OPSI. Serum IgM discriminated between patients with and without (AUC 0.92) with a cutoff of <61.5 mg/dL demonstrating an 86.7% sensitivity and 85.0% specificity for OPSI.

CONCLUSION

Low serum IgM was strongly associated with OPSI and may help identify patients requiring closer surveillance and management.