What is the incidence of Overwhelming Post-Splenectomy Infection (OPSI)?

Incidence of Overwhelming Post-Splenectomy Infection (OPSI)

The incidence of Overwhelming Post-Splenectomy Infection (OPSI) is 0.5-2% according to the most recent guidelines, placing it in the 1-5% range of the available options. 1

Definition and Clinical Significance

• OPSI is defined as fulminant sepsis, meningitis, or pneumonia primarily triggered by encapsulated bacteria, with Streptococcus pneumoniae accounting for approximately 50% of cases 1
• Other common causative organisms include Haemophilus influenzae type B and Neisseria meningitidis 1
• OPSI represents a true medical emergency with mortality rates ranging from 30-70%, with most deaths occurring within the first 24 hours 1

Risk Factors and Timing

• The risk of OPSI and associated death is highest in the first year after splenectomy, but remains elevated for more than 10 years and likely for life 1
• Children under 5 years of age have a significantly greater risk of OPSI with increased mortality compared to adults 1
• The risk is particularly high in neonates, exceeding 30% 1
• Patients who have undergone splenectomy have a lifetime risk of approximately 5% 2

Prevention Strategies

• Vaccination against encapsulated bacteria (S. pneumoniae, H. influenzae type B, N. meningitidis) is strongly recommended for all asplenic patients 1, 3

• Optimal timing for vaccination is:

  • At least 2 weeks before elective splenectomy 4
  • No sooner than 14 days after emergency splenectomy, as antibody response is suboptimal before this time 1
  • If there's high risk of missing vaccination in patients discharged before 15 days post-splenectomy, vaccination should be given before discharge 1

• Annual influenza vaccination is recommended for all asplenic patients over 6 months of age 1, 3

• Malaria prophylaxis is strongly recommended for asplenic travelers to endemic areas 1

Management Considerations

• Antibiotic therapy should be immediately initiated at the onset of any unexplained fever, malaise, chills, or other constitutional symptoms 1
• Patients should be provided with emergency standby antibiotics for immediate use when medical review is not readily accessible 1
• Primary care providers must be informed of the patient's asplenic status to ensure appropriate care 1

Special Considerations

• Hyposplenic patients (e.g., after splenic embolization) should also be considered at risk and should receive the same preventive measures 1
• Current vaccines do not provide complete coverage against all serotypes of encapsulated bacteria, highlighting the need for additional preventive measures 1
• OPSI can occur even decades after splenectomy, emphasizing the lifelong risk 5

Despite the relatively low incidence of 0.5-2%, the high mortality rate of OPSI makes prevention through vaccination, education, and prompt treatment of suspected infections crucial for all asplenic patients 1, 6.