Mode of splenectomy and immunogenicity of meningococcal vaccination in patients with hereditary spherocytosis

[Congenital hemolytic anemias due to erythrocyte membrane and enzyme defects]

Erythrocyte membrane and enzyme defects are the most common cause of congenital hemolytic anemias in the Central European population. Diagnostics include erythrocyte morphology, special biochemical tests such as osmotic fragility (AGLT) and EMA. For enzymopenic hemolytic anemias, cost-effective biochemical analysis remains the gold standard, supplemented by molecular genetic diagnostics when appropriate. Therapeutically, near complete splenectomy reduces hemolysis significantly for spherocytosis. The residual spleen at least provides a considerable phagocytic function and better response to immunisation and by inference possibly better protection against severe post-splenectomy infection. For pyruvate kinase deficiency, which is not so rare, a new molecular therapy (Mitapivat) is currently being introduced. In G6PD deficiency, there are very few drugs that cause hemolytic crisis. Sudden onset of hemoglobinuria is an early important hallmark of severe hemolytic crisis in G6PD deficiency and these patients should be hospitalized. Aplastic crises in the setting of parvovirus B19 infection occur in all congenital hemolytic anemias. Transfusion is not preventable in most cases. Iron-excreting treatment is required in the rare patients in need of chronic transfusion.

Comorbidity increases the risk of invasive meningococcal disease in adults

BACKGROUND

Risk of invasive meningococcal disease (IMD) is increased in patients with complement deficiency and HIV infection. Risk associated with comorbidity is not well described.

METHODS

Nationwide adult case-control study. Cases for the period 1977-2018 were identified by the national meningococcus reference laboratory. Matched controls were identified by registry linkage. Comorbidity diagnosed prior to IMD were based on the International Classification of Disease, eight or tenth revision. Odds ratios (OR) with 95% confidence intervals were estimated by logistic regression after adjustment for sex, age and other comorbidities.

RESULTS

We identified 1221 cases (45% male), median age 45 years (interquartile range: 22-64 years). The dominant meningococcal serogroups were B (n=738) and C (n=337). Increased risk of IMD was associated with solid organ transplantation (SOT) (OR 40.29 [95% confidence interval (CI), 4.84-335.75]), hemolytic anemia (OR 7.56 [95% CI, 2.63-21.79]), renal disease (OR 2.95 [95% confidence interval (CI), 1.77- 4.91]), liver disease (OR 2.53 [95% CI, 1.57-4.08]), cancer (OR 2.31 [95% CI, 1.85-2.89 ]), diabetes (OR 1.74 [95% CI, 1.26-2.39]), neurological disease (OR 1.72 [95% CI, 1.20-2.46]) and autoimmune disease (OR 1.70 [95% CI, 1.33-2.19]). Having 1, 2 and >2 comorbidities was associated with increased risk of IMD with ORs 1.6 to 3.5. Increased risk was not associated with specific serogroups.

CONCLUSIONS

This study of adults with IMD over four decades showed increased risk of IMD associated with renal disease, immunological disorders, liver disease, cancer, and SOT ranging from a 2- to a 40-fold increased risk. Vaccination may be warranted in these populations.

Total versus partial splenectomy in pediatric hereditary spherocytosis: A systematic review and meta-analysis

To compare the clinical effectiveness of total splenectomy (TS) or partial splenectomy (PS) in pediatric hereditary spherocytosis, a systematic review and meta-analysis was performed (PROSPERO registration CRD42015030056). There were 14 observational studies comparing pre- and postoperative hematologic parameters. Secondary outcomes include in-hospital infections, surgical complications, symptomatic recurrence, and biliary disease. TS is more effective than PS to increase hemoglobin (3.6 g/dl vs. 2.2 g/dl) and reduce reticulocytes (12.5% vs. 6.5%) after 1 year; outcomes following PS are stable for at least 6 years. There were no cases of overwhelming postsplenectomy sepsis. A population-based patient registry is needed for long-term follow-up.

Background Paper for the update of meningococcal vaccination recommendations in Germany: use of the serogroup B vaccine in persons at increased risk for meningococcal disease

In December 2013 Bexsero® became available in Germany for vaccination against serogroup B meningococci (MenB). In August 2015 the German Standing Committee on Vaccination (STIKO) endorsed a recommendation for use of this vaccine in persons at increased risk of invasive meningococcal disease (IMD). This background paper summarizes the evidence underlying the recommendation. Bexsero® is based on surface protein antigens expressed by about 80% of circulating serogroup B meningococci in Germany. The paper reviews available data on immunogenicity and safety of Bexsero® in healthy children and adolescents; data in persons with underlying illness and on the effectiveness in preventing clinical outcomes are thus far unavailable.STIKO recommends MenB vaccination for the following persons based on an individual risk assessment: (1) Persons with congenital or acquired immune deficiency or suppression. Among these, persons with terminal complement defects and properdin deficiency, including those under eculizumab therapy, are at highest risk with reported invasive meningococcal disease (IMD) incidences up 10,000-fold higher than in the general population. Persons with asplenia were estimated to have a ~ 20-30-fold increased risk of IMD, while the risk in individuals with other immune defects such as HIV infection or hypogammaglobulinaemia was estimated at no more than 5-10-fold higher than the background risk. (2) Laboratory staff with a risk of exposure to N. meningitidis aerosols, for whom an up to 271-fold increased risk for IMD has been reported. (3) Unvaccinated household (-like) contacts of a MenB IMD index case, who have a roughly 100-200-fold increased IMD risk in the year after the contact despite chemoprophylaxis. Because the risk is highest in the first 3 months and full protective immunity requires more than one dose (particularly in infants and toddlers), MenB vaccine should be administered as soon as possible following identification of the serogroup of the index case.

Polysaccharide-protein conjugate vaccination induces antibody production but not sustained B-cell memory in the human nasopharyngeal mucosa

Colonization of the nasopharyngeal mucosa by meningococcus and other polysaccharide (PS)-encapsulated bacteria precedes invasion. PS-conjugate vaccines induce PS-specific B-cell memory (B(MEM)) and also prevent colonization, thus blocking person-to-person transmission, generating herd protection. However, in isolation the B(MEM) are unable to sustain immunity. Furthermore, the duration of herd protection the vaccines induce appears limited. We demonstrate that, despite the persistence of PS-specific B(MEM), the population is not maintained within the nasopharynx. Although booster immunization results in the transient appearance of PS-specific B(MEM) within the mucosa, this reflects the re-circulation of systemic B(MEM) through the site rather than the generation of resident mucosal B(MEM). The induction of sustained PS-specific B(MEM) in the nasopharynx would allow the population to be activated by colonization, thus inhibiting subsequent invasion. It would also be expected to boost local mucosal immunity, thus extending herd protection. Strategies to generate PS-specific B(MEM) in the mucosa warrant further investigation.

Immunogenicity of a meningococcal serogroup C conjugate vaccine in HIV-infected children, adolescents, and young adults

Children and adolescents infected with HIV typically have a lower response to immunization than do those in the general population. In most developed countries, meningococcal serogroup C conjugate vaccine is one of the recommended vaccines for such individuals. However, there have been no studies evaluating the antibody response to this vaccine in HIV-infected children, adolescents or young adults. In this study, we evaluated that response using serum bactericidal antibody (SBA) and enzyme-linked immunosorbent assay, comparing HIV-infected with non-HIV-infected patients, as well as analysing the occurrence of side effects. In non-responders, we assessed the antibody response to revaccination. This clinical trial involved 92 patients between 10 and 20 years of age: 43 HIV-infected patients (HIV+ group) and 49 non-HIV-infected patients (HIV- group). After one dose of the vaccine, 72.1% of the HIV+ group patients and 100% of the HIV- group patients were considered protected. Of the HIV+ group patients who received a second dose of the vaccine, only 40% acquired protection. Overall, 81.4% of the HIV+ group patients acquired protection (after one or two doses of the vaccine). Side effects occurred in 16.3% and 44% of the HIV+ group and HIV- group patients, respectively. Therefore, the meningococcal serogroup C conjugate vaccine proved to be safe and effective for use in HIV-infected children, adolescents, and young adults, although their antibody response was weaker than that shown by non-HIV-infected patients. This indicates the need to discuss changes to the immunization schedule for children, adolescents, and young adults infected with HIV, in order to ensure more effective protection against meningococcal disease.

Comparative effectiveness of different types of splenectomy for children with congenital hemolytic anemias

OBJECTIVE

To compare the effectiveness of different types of splenectomy in children with congenital hemolytic anemias.

STUDY DESIGN

We constructed key questions that addressed outcomes relevant to clinicians and families on effects of partial or total splenectomy, including hematologic effect, splenic function, and the risk of adverse events. We identified from Pubmed and Embase 703 studies that evaluated different types of splenectomy and accepted 93 studies that satisfied entry criteria. We graded the quality of each report and summarized the overall strength of research evidence for each key question.

RESULTS

We did not identify any randomized clinical trials. All types of splenectomy have favorable clinical outcomes in most diseases. We did not identify any hematologic advantage of laparoscopy compared with laparotomy. Adverse events are uncommon in most studies and are minimized with use of laparoscopy.

CONCLUSIONS

There is a need for randomized clinical trials and improved data collection of different types of splenectomy in congenital hemolytic anemias. Outcomes studied should address the concerns of families and clinicians to assess the risks and benefits of various treatments.

Partial splenectomy for hereditary spherocytosis: a multi-institutional review

BACKGROUND/PURPOSE

Partial splenectomy has emerged as a surgical option for selected children with hereditary spherocytosis, with the goal of reducing anemia while preserving splenic function. This multi-institutional study is the largest series to date examining outcomes data for partial splenectomy in patients with hereditary spherocytosis.

METHODS

Data were collected retrospectively from 5 North American pediatric hospitals. Sixty-two children underwent partial splenectomy for hereditary spherocytosis between 1990 and 2008.

RESULTS

At 1 year following partial splenectomy, mean hemoglobin significantly increased by 3.0 ± 1.4 g/dL (n = 52), reticulocyte count decreased by 6.6% ± 6.6% (n = 41), and bilirubin level decreased by 1.3 ± 0.9 mg/dL (n = 25). Patients with poor or transient hematologic response were found to have significantly more splenic regeneration postoperatively compared with patients with a durable clinical response (maximal spleen dimension, 9.0 ± 3.4 vs 6.3 ± 2.2 cm). Clinically significant recurrence of anemia or abdominal pain led to completion splenectomy in 4.84% of patients. No patients developed postsplenectomy sepsis.

CONCLUSIONS

Our multi-institutional review indicates that partial splenectomy for hereditary spherocytosis leads to sustained and clinically significant improvement in hematologic profiles and clinical symptoms in most patients. Our data support partial splenectomy as an alternative for selected children with hereditary spherocytosis.