Protocol for the unclassified primary antibody deficiency (unPAD) study: Characterization and classification of patients using the ESID online Registry.

BACKGROUND: Primary antibody deficiencies (PADs) without an identified monogenetic origin form the largest and most heterogeneous group of primary immunodeficiencies. These patients often remain undiagnosed for years and many present to medical attention in adulthood after several infections risking structural complications. Not much is known about their treatment, comorbidities, or prognosis, nor whether the various immunological forms (decreased total IgG, IgG subclass(es), IgM, IgA, specific antibody responses, alone or in combination(s)) should be considered as separate, clearly definable subgroups. The unclassified primary antibody deficiency (unPAD) study aims to describe in detail all PAD patients without an identified specific monogenetic defect regarding their demographical, clinical, and immunological characteristics at presentation and during follow-up. In constructing these patterns, the unPAD study aims to reduce the number of missed and unidentified PAD patients in the future. In addition, this study will focus on subclassifying unPAD to support the identification of patients at higher risk for infection or immune dysregulation related complications, enabling the development of personalized follow-up and treatment plans. METHODS AND ANALYSIS: We present a protocol for a multicenter observational cohort study using the ESID online Registry. Patients of all ages who have given informed consent for participation in the ESID online Registry and fulfill the ESID Clinical Working Definitions for 'unclassified antibody deficiency', 'deficiency of specific IgG', 'IgA with IgG subclass deficiency', 'isolated IgG subclass deficiency', 'selective IgM deficiency', 'selective IgA deficiency' or 'common variable immunodeficiency' will be included. For all patients, basic characteristics can be registered at first registration and yearly thereafter in level 1 forms. Detailed characteristics of the patients can be registered in level 2 forms. Consecutive follow-up forms can be added indefinitely. To ensure the quality of the collected data, all data will be fully monitored before they are exported from the ESID online Registry for analysis. Outcomes will be the clinical and immunological characteristics of unPAD at presentation and during follow-up. Subgroup analyses will be made based on demographical, clinical and immunological characteristics.

Which triggers could support timely identification of primary antibody deficiency? A qualitative study using the patient perspective.

BACKGROUND: Patients with predominantly (primary) antibody deficiencies (PADs) commonly develop recurrent respiratory infections which can lead to bronchiectasis, long-term morbidity and increased mortality. Recognizing symptoms and making a diagnosis is vital to enable timely treatment. Studies on disease presentation have mainly been conducted using medical files rather than direct contact with PAD patients. Our study aims to analyze how patients appraised their symptoms and which factors were involved in a decision to seek medical care. METHODS: 14 PAD-patients (11 women; median 44, range 16-68 years) were analyzed using semi-structured interviews until saturation of key emergent themes was achieved. RESULTS: Being always ill featured in all participant stories. Often from childhood onwards periods of illness were felt to be too numerous, too bad, too long-lasting, or antibiotics were always needed to get better. Recurrent or persistent respiratory infections were the main triggers for patients to seek care. All participants developed an extreme fatigue, described as a feeling of physical and mental exhaustion and thus an extreme burden on daily life that was not solved by taking rest. Despite this, participants tended to normalize their symptoms and carry on with usual activities. Non-immunologists, as well as patients, misattributed the presenting signs and symptoms to common, self-limiting illnesses or other 'innocent' explanations. Participants in a way understood the long diagnostic delay. They know that the disease is rare and that doctors have to cover a broad medical area. But they were more critical about the way the doctors communicate with them. They feel that doctors often don't listen very well to their patients. The participants' symptoms as well as the interpretation of these symptoms by their social environment and doctors had a major emotional impact on the participants and a negative influence on their future perspectives. CONCLUSIONS: To timely identify PAD, 'pattern recognition' should not only focus on the medical 'red flags', but also on less differentiating symptoms, such as 'being always ill' and 'worn out' and the way patients cope with these problems. And, most important, making time to really listen to the patient remains the key.

The clinical relevance of IgM and IgA anti-pneumococcal polysaccharide ELISA assays in patients with suspected antibody deficiency.

Unlike immunoglobulin (Ig)G pneumococcal polysaccharide (PnPS)-antibodies, PnPS IgA and IgM-antibodies are not routinely determined for the assessment of immunocompetence. It is not yet known whether an isolated inability to mount a normal IgM or IgA-PnPS response should be considered a relevant primary antibody deficiency (PAD). We studied the clinical relevance of anti-PnPS IgM and IgA-assays in patients with suspected primary immunodeficiency in a large teaching hospital in 's-Hertogenbosch, the Netherlands. Serotype-specific-PnPS IgG assays were performed; subsequently, 23-valent-PnPS IgG assays (anti-PnPS IgG assays), and later anti-PnPS IgA and IgM assays, were performed in archived material (240 patients; 304 samples). Eleven of 65 pre- and six of 10 post-immunization samples from good responders to PnPS serotype-specific IgG testing had decreased anti-PnPS IgA and/or IgM titres. Of these, three pre- and no post-immunization samples were from patients previously classified as 'no PAD'. Determination of anti-PnPS IgA and IgM in addition to anti-PnPS IgG did not reduce the need for serotype-specific PnPS IgG testing to assess immunocompetence [receiver operating characteristic (ROC) analysis of post-immunization samples: anti-PnPS IgA + IgG area under the curve (AUC) = 0.80, 95% confidence interval (CI) = 0.63-0.97; anti-PnPS IgM + IgG AUC 0.80, 95% CI = 0.62-0.98; anti-PnPS IgA + IgG + IgM AUC = 0.71, 95% CI = 0.51-0.91; anti-PnPS IgG AUC = 0.93, 95% CI = 0.85-1.00]. Our data show that patients classified as having an intact antibody response based on measurement of serotype-specific PnPS IgG can still display impaired anti-PnPS IgM and IgA responses, and that the additional measurement of anti-PnPS IgA and IgM could not reduce the need for serotype-specific IgG testing. Future studies are needed to investigate the clinical relevance of potential 'specific IgA or IgM antibody deficiency' in patients with recurrent airway infections in whom no PAD could be diagnosed according to the current definitions.

Lessons Learned From the Clinical Presentation of Common Variable Immunodeficiency Disorders: A Systematic Review and Meta-Analysis.

Background: Diagnostic delay in common variable immunodeficiency disorders (CVID) is considerable. There is no generally accepted symptom-recognition framework for its early detection. Objective: To systematically review all existing data on the clinical presentation of CVID. Methods: PubMed, EMBASE and Cochrane were searched for cohort studies, published January/1999-December/2019, detailing the clinical manifestations before, at and after the CVID-diagnosis. Results: In 51 studies (n=8521 patients) 134 presenting and 270 total clinical manifestations were identified. Recurrent upper and/or lower respiratory infections were present at diagnosis in 75%. Many patients had suffered severe bacterial infections (osteomyelitis 4%, meningitis 6%, septicemia 8%, mastoiditis 8%). Bronchiectasis (28%), lymphadenopathy (27%), splenomegaly (13%), inflammatory bowel disease (11%), autoimmune cytopenia (10%) and idiopathic thrombocytopenia (6%) were also frequently reported. A bimodal sex distribution was found, with male predominance in children (62%) and female predominance in adults (58%). 25% of CVID-patients developed other manifestations besides infections in childhood, this percentage was much higher in adults (62%). Immune-dysregulation features, such as granulomatous-lymphocytic interstitial lung disease and inflammatory bowel disease, were more prominent in adults. Conclusions: The shift from male predominance in childhood to female predominance in adults suggests differences in genetic and environmental etiology in CVID and has consequences for pathophysiologic studies. We confirm the high frequency of respiratory infections at presentation, but also show a high incidence of severe bacterial infections such as sepsis and meningitis, and immune dysregulation features including lymphoproliferative, gastrointestinal and autoimmune manifestations. Early detection of CVID may be improved by screening for antibody deficiency in patients with these manifestations.

Focusing on Good Responders to Pneumococcal Polysaccharide Vaccination in General Hospital Patients Suspected for Immunodeficiency. A Decision Tree Based on the 23-Valent Pneumococcal IgG Assay.

Background and Aim: Recently, the 23-valent IgG-assay was suggested as screening assay to identify poor responders to pneumococcal polysaccharide (PnPS)-vaccination with the serotype-specific assay as a second-line test. However, in a low pre-test probability general hospital setting predicting good responders could be more valuable to reduce the number of samples needing serotyping. Methods: Serotype-specific PnPS antibody-assays were performed for suspected immunodeficiency in two Dutch general hospitals (Jeroen Bosch Hospital, 's-Hertogenbosch; Elisabeth Tweesteden Hospital, Tilburg). 23-Valent PnPS antibody-assays were subsequently performed in archived material. Data were analyzed using receiver operating characteristic curves (AUC) and agreement indices (ICC). Results: Sera of 284 patients (348 samples) were included; 23-valent IgG-titres and the corresponding sum of PnPS-serotype specific antibodies showed moderate correlation (ICC = 0.63). In 232 conjugated-pneumococcal-vaccine-naïve patients (270 samples), a random 23-valent IgG-titer could discriminate between samples with and without ≥7/11, ≥7/13, or ≥6/9 pneumococcal serotypes when both cut-off values 0.35 and 1.0 µg/ml were used (AUC 0.86 and 0.92, respectively). All patients with a pre-immunization-titer ≥38.2 µg/ml and/or post-immunization-titer ≥96.1 µg/ml and none with a post-immunization-titer ≤38.5 µg/ml exhibited a good response to PnPS vaccination. Using these breakpoints as screening test to predict good responders, only 24% of patients would require further serotyping, as opposed to 68% if breakpoints to predict poor responders would have been used. Conclusion: In a low pre-test probability setting, the 23-valent IgG-assay proved to be a reliable screening test for good responders in conjugated-pneumococcal-vaccine-naïve patients, reducing the overall number of patient samples needing further serotyping, thus reducing overall costs of pneumococcal vaccination response assessment.

Challenges in investigating patients with isolated decreased serum IgM: The SIMcal study.

The clinical consequences of isolated decreased serum immunoglobulin (Ig)M are not sufficiently known. Therefore, it is difficult to determine the clinical policy following such a finding. Only few reported IgM-deficient patients fulfil the European Society for Immunodeficiencies (ESID) diagnostic criteria for selective IgM deficiency (true sIgMdef), or their diagnosis is uncertain due to insufficient laboratory data (possible sIgMdef). Decreased serum IgM is often incidentally found in asymptomatic adults. The objective of our study was to further characterize true sIgMdef and to compare the European data collected through the ESID Registry community (tertiary centres) to our previously published Dutch cohort (secondary centre). Fifteen centres (12 countries) participated with 98 patients. Patients were excluded if serum IgM was only determined once (n = 14), had normalized (n = 8), or if they also had other immunological abnormalities (n = 15). Ten patients (5 adults) completely fulfilled the ESID criteria for true sIgMdef. Age-matched cut-off values varied widely between centres; when using the ESID diagnostic protocol reference values, only six patients (five adults) had true sIgMdef. Because of these small numbers, further analyses were performed in patients with true or possible sIgMdef (13 adults, 48 children). Respiratory infections were commonly reported at presentation (adults 54%, children 60%). Symptomatic adults had lower serum IgM levels (mean 0.27 g/L, 95% CI 0.22-0.31) than those without symptoms (mean 0.33 g/L, 95% CI 0.30-0.36; P = 0.02). To be able to explore the clinical consequences of true sIgMdef, we should fully analyse and accurately describe those patients in whom a decreased serum IgM is found.

Mild Hypogammaglobulinemia Can Be a Serious Condition.

Background: Most patients with primary antibody deficiency (PAD) suffer from less well-described and understood forms of hypogammaglobulinemia (unclassified primary antibody deficiency, unPAD). Because of the moderately decreased immunoglobulin levels compared to CVID, unPAD is generally considered to be clinically mild and not very relevant. Objective: To describe our cohort of-mainly-unPAD patients, and to analyze whether subgroups can be identified. Methods: Data were prospectively collected (February-2012 to June-2016) as part of a standardized, 1-day Care Pathway for suspected primary immunodeficiency. The TNO-AZL Questionnaire for Health-Related Quality of Life (HRQoL) was part of the pre-first-visit intake procedure. Results: Three hundred and twenty patients were referred to the Care Pathway. Data from 23/27 children and 99/113 adults who were diagnosed with PAD and gave informed consent were available for analysis. 89/99 adults had unPAD, the majority (74%) were female and 44% already showed bronchiectasis. HRQoL was significantly decreased in all domains, meaning that a lot of unPAD patients had to cope simultaneously with pain, negative feelings and impairments in cognition, home management tasks, sleep, social interaction, and work. The most prominently impaired HRQoL domain was vitality, indicating these patients feel extremely tired and worn out. Conclusion: These results highlight the need for more attention to the potential patient burden of unPADs. A larger cohort is needed to increase our understanding of unPADs and to analyze whether distinct subgroups can be identified. For now, it is important for the clinician to acknowledge the existence of unPAD and be aware of its potential consequences, in order to timely and appropriately manage its effects and complications.

0.2% chlorhexidine acetate as skin disinfectant prevents skin lesions in extremely preterm infants: a preliminary report.

OBJECTIVE: The skin disinfectant '0.5% chlorhexidine gluconate in 70% alcohol' (0.5% CHG-70% alc) may cause skin lesions in extremely preterm infants (gestational age <26 weeks). In April 2013, 0.2% chlorhexidine gluconate solution in acetate (0.2% CHG-acetate) was introduced as skin disinfectant for extremely preterm infants in our neonatal intensive care units. We aimed to compare the incidence of skin lesions and central line-associated bloodstream infection (CLABSI) among extremely preterm infants when using 0.5% CHG-70% alc and 0.2% CHG-acetate. DESIGN: Retrospective pre-post comparison cohort study. PATIENTS: All electronic patient records of extremely preterm infants born between January 2011-March 2013 ('0.5% CHG-70% alc' cohort) and April 2013-October 2015 ('0.2% CHG-acetate' cohort) were reviewed. MAIN OUTCOME MEASURES: The incidence of skin lesions and CLABSI. Skin lesions were defined as the presence of erythema, blisters, excoriation, oedema or induration. CLABSI was defined according to the definition of the US Centers for Disease Control and Prevention. RESULTS: The incidence of skin lesions was 22% (95% CI 11% to 37%) in the '0.5% CHG-70% alc' cohort (n=41) and 5% (95% CI 1% to 15%; p=0.02) in the '0.2% CHG-acetate' cohort (n=41). The incidence of CLABSI was the same in both groups (28%; 95% CI 14% to 46% in '0.5% CHG-70% alc' vs 27%; 95% CI 14% to 44% in '0.2% CHG-acetate'; p=0.98). CONCLUSIONS: Using 0.2% CHG-acetate as skin disinfectant in extremely preterm infants resulted in statistically significant reduction of skin lesions, without increasing the risk of CLABSI as compared with 0.5% CHG-70% alc.