Pneumococcal and influenza immunization in asplenic persons: a retrospective population-based cohort study 1990-2002

Abstract

BackgroundSplenectomy is associated with increased risk for bacteremia, due to impaired clearance of bloodborne agents and to altered phagocytosis and humoral immunity. We conducted a retrospective cohort study of patients at risk for splenectomy for a 13-year period to determine immunization coverage, and outcomes of those with and without splenectomy, and with or without receipt of influenza or pneumococcal vaccine.MethodsData were extracted from the provincial Medical Services Insurance database for insured services rendered by a physician for 1990-2002, and from the Vital Statistics Death database. The eligible cohort was selected based on diagnostic codes for hematologic conditions for which splenectomy might be considered, such as immune thrombocytopenia. Each patient was followed longitudinally from the date of first diagnosis until 31Dec2002, or death, or relocation out-of province. In addition, persons with splenectomy and no hematologic condition were identified and followed for 6 months post-surgery. Infectious illness rates per 100 person-years of observation and death rates were calculated with and without splenectomy. Death rates were determined using splenectomy status as a time-dependent covariate. The relationship between splenectomy and death according to immunization status was examined using Cox proportional hazard ratios.ResultsOf 38,812 persons in the cohort 427 subjects with a hematologic diagnosis had splenectomy and another 452 subjects without a hematologic diagnosis had this surgery. 72% were > 18 years of age. Pneumococcal immunization was recorded in 16.5% of asplenic patients overall, and was not associated with reduced risk of death in these persons (adjusted Hazard Ratio [HR] = 1.07, 95% CI 0.70 - 1.65). Influenza immunization was recorded in 53.1% of asplenic patients overall, and was associated with reduced risk of death (adjusted HR = 0.46, 0.33-0.62). No pneumococcal or influenza immunization was recorded in patients with a hematologic diagnosis without splenectomy. Infectious illness visits were higher among all patients who had a splenectomy than among those without a splenectomy (151 visits/100 person-years of observation in the post-splenectomy period vs. 120 visits/100 person-years; p < 0.0001).ConclusionsIn asplenic patients, influenza immunization is associated with a 54% reduced risk of death compared to unimmunized asplenic persons; no reduction in risk was demonstrated with (polysaccharide) pneumococcal vaccine. Vaccine coverage in the entire cohort was less than routinely recommended. Improved delivery of infection prevention programs to this population is warranted. Conjugate pneumococcal vaccines should be urgently studied in this immunocompromised population.

Splenektomi yapılan hastaların aşılanmalarının ve bu konudaki bilgilerinin değerlendirilmesi

“…Pnömokok aşısı, çalışma kapsamında değerlendirilen olguların %62,7'sine operasyon öncesi, %23,5'ine operasyon sonrası uygulanmışken, Görkem ve arkadaşlarının çalışmasında [9] olguların %87,1'ine operasyon öncesi %12,9'una operasyon sonrası, Özkören ve arkadaşlarının çalışmasında [8] olguların %41'ine operasyon öncesi %33,3'üne operasyon sonrası yapıldığı görülmüştür. Ayrıca pnömokok aşısı Kyaw ve arkadaşlarının çalışmasında [17] olguların %88'ine uygulanmışken, bu oran Langley ve arkadaşlarının çalışmasında [18] %16,5 olarak belirlenmiştir. Ülkemizde yapılan çalışmalarda H. influenzae tip B konjuge aşısının ve meningokok aşısının uygulama oranları hakkında veriler bulunmazken, H. influenzae tip B konjuge aşısı sunulan çalışmada olguların %72,6'sına, Kyaw ve arkadaşlarının çalışmasında [17] %70'ine ve Langley ve arkadaşlarının çalışmasında [18] ise %53,1'ine uygulanmıştır.…”

“…Ayrıca pnömokok aşısı Kyaw ve arkadaşlarının çalışmasında [17] olguların %88'ine uygulanmışken, bu oran Langley ve arkadaşlarının çalışmasında [18] %16,5 olarak belirlenmiştir. Ülkemizde yapılan çalışmalarda H. influenzae tip B konjuge aşısının ve meningokok aşısının uygulama oranları hakkında veriler bulunmazken, H. influenzae tip B konjuge aşısı sunulan çalışmada olguların %72,6'sına, Kyaw ve arkadaşlarının çalışmasında [17] %70'ine ve Langley ve arkadaşlarının çalışmasında [18] ise %53,1'ine uygulanmıştır. Meningokok aşısı da bu çalışmada olguların %72,6'sına uygulanmışken, Kyaw ve arkadaşlarının çalışmasında [17] %51'ine uygulanmıştır.…”

Recommended immunization schedules for adults: Clinical practice guidelines by the Escmid Vaccine Study Group (EVASG), European Geriatric Medicine Society (EUGMS) and the World Association for Infectious Diseases and Immunological Disorders (WAidid)

“…Trivalent influenza vaccine (TIV) is effective in reducing: (i) ILI after vaccination in patients with HIV infection, those with cancer, those undergoing peritoneal dialysis and hematopoietic stem cell transplantation (HSCT) recipients; (ii) laboratory-confirmed influenza in HIV-infected patients, compared with patients receiving placebo or no vaccination; (iii) hospitalisation in adults with cancer and haematological malignancies; (iv) pneumonia in patients undergoing haemodialysis and in solid organ transplant (SOT) recipients; and (v) mortality in immunosuppressed adults with cancer, in those who are asplenic and in haemodialysis patients. [99][100][101][102] In these patients, the immune response was typically lower in comparison with that in immunocompetent controls. [99][100][101][102] In HIV-infected patients, vaccination was generally well tolerated, although a transient increase in viremia and decrease in the percentage of CD4C cells (not accompanied by worsening of clinical symptoms) was reported in some studies.…”

“…[99][100][101][102] In these patients, the immune response was typically lower in comparison with that in immunocompetent controls. [99][100][101][102] In HIV-infected patients, vaccination was generally well tolerated, although a transient increase in viremia and decrease in the percentage of CD4C cells (not accompanied by worsening of clinical symptoms) was reported in some studies. 100,103 Inactivated influenza vaccines do not trigger rejection episodes and should not be withheld in transplant recipients for that reason.…”

What do the next 100 years hold for pneumococcal vaccination?

“…These include the elderly and a variety of conditions associated with impaired immunity such as splenectomy [33][34][35], malignancy [36,37], stem cell transplantation [38] specific defects [39]. Whether the pneumococcal conjugate vaccines will be clinically effective in preventing community-acquired pneumonia in the elderly is currently being investigated in ongoing studies [40].…”