The diagnosis of hypersensitivity to antibiotics is rarely confirmed by allergy work-up in cystic fibrosis patients.

Cystic fibrosis (CF) patients receive many antibiotic treatments for recurrent respiratory infections and frequently report antibiotic hypersensitivity reactions (HSRs). In this retrospective study, medical records of CF patients were reviewed to clarify the clinical features, the culprit antibiotics, and the prevalence of antibiotic HSRs in the CF population. From 601 CF patients, 95 suspected antibiotic HSRs occurred in 60 patients (prevalence of 10.0%). ß-Lactams were the most common inducers, but cotrimoxazole was also frequently involved. Seventy-six of 95 suspected HSRs were assessed by allergy workup including skin tests (43/76 reactions) and/or drug reintroduction as a full course of the culprit antibiotic (73 of 76 reactions). From the 43 suspected HSRs that were skin-tested, only three had positive skin tests and were not subjected to drug readministration. All the other 73 suspected HSRs received a full course of the culprit antibiotic: HSR symptoms recurred in 10 of 73 cases and therefore were considered as confirmed antibiotic HSRs; for the remaining 63 suspected HSRs that did not relapse after drug readministration, the diagnosis of antibiotic HSRs was excluded. In summary, 13 of 76 suspected HSRs were confirmed as antibiotic HSRs. The prevalence of suspected and confirmed antibiotic HSRs in CF patients appears similar to that reported in the general population. Of note, most of the antibiotic suspected HSRs are not confirmed after allergology workup. A complete allergy workup appears therefore crucial to make a correct diagnosis and to avoid unnecessary contraindication of major antibiotics.

Aminoglycoside exposure and renal function before lung transplantation in adult cystic fibrosis patients.

Background: Patients with cystic fibrosis (CF) are at risk of kidney injury even before undergoing lung transplantation, because of prolonged exposure to aminoglycosides (AGs), chronic dehydration and complications of diabetes mellitus. The usual equations estimating the glomerular filtration rate (GFR), such as Cockcroft-Gault and Modification of Diet in Renal Disease, are not adapted to the CF population due to patients' low body weight and reduced muscle mass. The aim of this study was to precisely measure GFR in adult CF patients and to see whether repeated AG treatment would impair renal function before lung transplantation. Methods: Inulin or iohexol clearances were performed in 25 adult CF patients when they entered the lung transplant waiting list. No patient was treated with AGs at the time of GFR measurement. Body mass index (BMI), history of diabetes mellitus and blood pressure were recorded. Exposure to intravenous (IV) AGs within 5 years prior to the GFR measurement was obtained from the patient's medical files. Urine samples were collected to check for albuminuria and proteinuria. Results: The population was predominantly female (67%). The mean age was 32 years, the mean BMI was 19 kg/m2 and 28% had CF-related diabetes. Median exposure to IV AG within 5 years before GFR measurement was 155 days with a mean dosage of 7.7mg/kg/day. The mean measured GFR was 106 mL/min/1.73 m2 and the mean estimated GFR according to the Chronic Kidney Disease Epidemiology Collaboration formula was 124 mL/min/1.73 m2. Conclusion: Despite prolonged exposure to high-dose IV AG, no decline in GFR was observed in these patients.

Risk of thrombosis with anti-phospholipid syndrome in systemic lupus erythematosus treated with thrombopoietin-receptor agonists.

OBJECTIVES: The use of thrombopoietin-receptor agonists (TPO-RAs) has increased as a second-line therapy in ITP, but the efficacy and safety of such drugs has not been evaluated in SLE-associated ITP. METHODS: This was a multicentre retrospective cohort study from 2009 to 2016. Participating centres (n = 11) were secondary- or tertiary-care hospitals belonging to the French national network for adult ITP. RESULTS: We included 18 patients with SLE-ITP treated with TPO-RAs; 10 (55%) had aPL, 5 (27%) showing definite APS. Except for one patient, all (94%) achieved response with TPO-RAs overall. After a median follow-up of 14.7 months with TPO-RAs, four arterial thrombosis events (including one catastrophic APS) occurred in four patients. Two venous thrombosis events occurred in a patient without APS or aPLs. CONCLUSION: Our results suggest that aPLs should be systematically screened before TPO-RA initiation in patients with SLE. With aPL positivity, alternative therapy should be discussed (if possible), especially in patients with definite APS or suboptimal adherence to anti-coagulation therapy.

Neutropenia in Patients with Common Variable Immunodeficiency: a Rare Event Associated with Severe Outcome.

BACKGROUND: Common variable immunodeficiency (CVID) is characterized by infections and hypogammaglobulinemia. Neutropenia is rare during CVID. METHODS: The French DEFI study enrolled patients with primary hypogammaglobulinemia. Patients with CVID and neutropenia were retrospectively analyzed. RESULTS: Among 473 patients with CVID, 16 patients displayed neutropenia (lowest count [0-1400]*106/L). Sex ratio (M/F) was 10/6. Five patients died during the follow-up (11 years) with an increased percentage of deaths compared to the whole DEFI group (31.3 vs 3.4%, P < 0.05). Neutropenia was diagnosed for 10 patients before 22 years old. The most frequent symptoms, except infections, were autoimmune cytopenia, i.e., thrombopenia or anemia (11/16). Ten patients were affected with lymphoproliferative diseases. Two patients were in the infection only group and the others belonged to one or several other CVID groups. The median level of IgG was 2.6 g/L [0.35-4.4]. Most patients presented increased numbers of CD21low CD38low B cell, as already described in CVID autoimmune cytopenia group. Neutropenia was considered autoimmune in 11 cases. NGS for 52 genes of interest was performed on 8 patients. No deleterious mutations were found in LRBA, CTLA4, and PIK3. More than one potentially damaging variant in other genes associated with CVID were present in most patients arguing for a multigene process. CONCLUSION: Neutropenia is generally associated with another cytopenia and presumably of autoimmune origin during CVID. In the DEFI study, neutropenia is coupled with more severe clinical outcomes. It appears as an "alarm bell" considering patients' presentation and the high rate of deaths. Whole exome sequencing diagnosis should improve management.

Rare and unusual presentation of Cladophialophora infection in a pulmonary transplant cystic fibrosis patient.

A 35-year-old woman with severe cystic fibrosis was admitted for sudden loss of strength in both legs, revealing a myelitis. The medullary lesion biopsy revealed phaeohyphomycosis caused by Cladophialophora species. Myelitis caused by Cladophialophora bantiana is a rare disease associated with high mortality.

Pregnancy outcome in women with cystic fibrosis-related diabetes.

INTRODUCTION: With increasing life expectancy, more women with cystic fibrosis and diabetes mellitus become pregnant. We investigated how pre-gestational diabetes (cystic fibrosis-related diabetes) influenced pregnancy outcome and the clinical status of these women. MATERIAL AND METHODS: We analyzed all pregnancies reported to the French cystic fibrosis registry between 2001 and 2012, and compared forced expiratory volume (FEV1 ) and body mass index before and after pregnancy in women with and without pre-gestational diabetes having a first delivery. RESULTS: A total 249 women delivered 314 infants. Among these, 189 women had a first delivery and 29 of these had pre-gestational diabetes. There was a trend towards a higher rate of assisted conception among diabetic women (53.8%) than non-diabetic women (34.5%, p = 0.06), and the rate of cesarean section was significantly higher in diabetic women (48% vs. 21.4%, p = 0.005). The rate of preterm birth and mean infant birthweight did not differ significantly between diabetic and non-diabetic women. Forced expiratory volume before pregnancy was significantly lower in the diabetic group. The decline in forced expiratory volume and body mass index following pregnancy did not differ between the women with and those without pre-gestational diabetes. CONCLUSION: Pre-gestational diabetes in women with cystic fibrosis is associated with a higher rate of cesarean section but does not seem to have a clinically significant impact on fetal growth or preterm delivery. The changes in maternal pulmonary and nutritional status following pregnancy in women with cystic fibrosis were not influenced by pre-gestational diabetes.

A French multicentric study and review of pulmonary Nocardia spp. in cystic fibrosis patients.

Some bacterial species recovered from the airways of cystic fibrosis (CF) patients are indisputably associated with lung infections, whereas the clinical relevance of others, such as Nocardia spp., remains unclear. Sixteen French CF cases of colonization/infection with Nocardia spp. were reviewed in order to evaluate the epidemiology, the clinical impact and the potential treatment of these bacteria, and results were compared to those of the literature. Five Nocardia species were identified, Nocardia cyriacigeorgica being the major species (50 % of cases). At first isolation, Nocardia was the sole pathogen recovered in six patients. Seven patients presented pulmonary exacerbation. For 12 patients, antimicrobial treatment against Nocardia was started immediately, mainly based on cotrimoxazole (6 of the 12 cases). In this study, we highlight the heterogeneity of the clinical management of Nocardia spp. in CF. Guidelines for the clinical management of Nocardia infections in CF patients are proposed.

Kidney effects of triple CFTR modulator therapy in people with cystic fibrosis.

Background: Elexacaftor/tezacaftor/ivacaftor (ETI) is a new cystic fibrosis transmembrane conductance regulator (CFTR) modulator that has transformed the respiratory prognosis of people with cystic fibrosis (pwCF). However, its impact on other organs such as the kidneys, where CFTR is expressed, remains unclear. Since pwCF are risk of both kidney disease and urolithiasis, we aimed to study the potential effects of ETI on renal function, volume status, and risk factors for urolithiasis. Methods: This prospective, observational, single-center, before-after cohort study, involved adult pwCF eligible for ETI. The changes in plasma and urinary profiles were assessed by comparing renal function (using 2021 CKD-EPIcreatinine and 2021 CKD-EPIcreatinine-cystatin C formulas), volume status (using aldosterone/renin ratio and blood pressure), and risk factors for urolithiasis, at the time of ETI introduction (M0) and 7 months after (M7). Results: Nineteen pwCF were included. No significant change in renal function was observed between M0 and M7 (2021 CKD-EPIcreatinine: 105.5 ml/min/1.73 m² at M0 vs. 103.3 ml/min/1.73 m² at M7; P = .17). There was a significant reduction in aldosterone level (370.3 pmol/l at M0 vs. 232.4 pmol/l at M7; P = .02) and aldosterone/renin ratio (33.6 at M0 vs. 21.8 at M7; P = .03). Among the risk factors for urolithiasis, a significant reduction in magnesuria level was found (4.6 mmol/d at M0 vs. 3.8 mmol/d at M7; P = .01). Conclusion: These findings suggest that ETI seem to have no short-term impact on the renal function of adult pwCF and appears to correct secondary hyperaldosteronism due to excessive sweat losses. Further investigations are needed to determine the potential impact of decreased magnesuria observed under ETI therapy on the risk of urolithiasis.

Outcome of cystic fibrosis-related diabetes two years after lung transplantation.

BACKGROUND: Although transplantation is known to impair glucose tolerance, evolution of pre-existing diabetes after lung transplantation (LT) in cystic fibrosis (CF) has never been described. OBJECTIVES: We aimed to assess the outcome of CF-related diabetes (CFRD) after LT, with the hypothesis that suppressing chronic inflammatory foci may improve glucose tolerance in some patients. METHODS: In a retrospective study of 29 CF diabetic patients treated with insulin and undergoing LT, CFRD control was assessed 3 months before LT and 1 (n = 27) and 2 (n = 18) years after LT by measuring insulin dosage, fasting blood glucose and glycosylated hemoglobin (HbA1c) levels. Patients with HbA1c ≤7% and an insulin dose ≤1 UI/kg/day were defined as having controlled CFRD (group A). Other patients were assigned to group B. RESULTS: Before LT, 19 (65.5%) patients were in group A. At 2 years, 6 of 10 (60%) patients who were in group B prior to LT had moved into group A, which then comprised 77.8% of all patients. Insulin could have been stopped in 5 patients. Uncontrolled CFRD before LT (OR = 16) and a long delay between the diagnosis of CFRD and LT (OR = 1.3) were significant predictors of uncontrolled CFRD at 1 year. CONCLUSIONS: LT does not seem to worsen CFRD in some patients, suggesting that in some cases, glucose tolerance may be improved by the suppression of chronic pulmonary infection.

Protective effect of IgM against colonization of the respiratory tract by nontypeable Haemophilus influenzae in patients with hypogammaglobulinemia.

BACKGROUND: Primary immunoglobulin deficiencies lead to recurrent bacterial infections of the respiratory tract and bronchiectasis, even with adequate immunoglobulin replacement therapy. It is not known whether patients able to secrete IgM (eg, those with hyper-IgM [HIgM] syndrome) are as susceptible to these infections as patients who lack IgM production (eg, those with panhypogammaglobulinemia [PHG]). OBJECTIVE: This study is aimed at identifying specific microbiological and clinical (infections) characteristics that distinguish immunoglobulin-substituted patients with PHG from patients with HIgM syndrome. METHODS: A cohort of patients with HIgM syndrome (n = 25) and a cohort of patients with PHG (n = 86) were monitored prospectively for 2 years while receiving similar polyvalent immunoglobulin replacement therapies. Regular bacterial analyses of nasal swabs and sputum were performed, and clinical events were recorded. In parallel, serum and saliva IgM antibody concentrations were measured. RESULTS: When compared with patients with PHG, patients with HIgM syndrome were found to have a significantly lower risk of nontypeable Haemophilus influenzae carriage in particular (relative risk, 0.39; 95% CI, 0.21-0.63). Moreover, patients with HIgM syndrome (including those unable to generate somatic hypermutations of immunoglobulin genes) displayed anti-nontypeable H influenzae IgM antibodies in their serum and saliva. Also, patients with HIgM syndrome had a lower incidence of acute respiratory tract infections. CONCLUSIONS: IgM antibodies appear to be microbiologically and clinically protective and might thus attenuate the infectious consequences of a lack of production of other immunoglobulin isotypes in patients with HIgM syndrome. Polyvalent IgG replacement therapy might not fully compensate for IgM deficiency. It might thus be worth adapting long-term antimicrobial prophylactic regimens according to the underlying B-cell immunodeficiency phenotype.

Iron Deficiency in Cystic Fibrosis: A Cross-Sectional Single-Centre Study in a Referral Adult Centre.

Iron deficiency (ID) diagnosis in cystic fibrosis (CF) is challenging because of frequent systemic inflammation. We aimed to determine the prevalence and risk factors of ID in adult patients with CF. We conducted a single-centre prospective study in a referral centre. ID was defined by transferrin saturation ≤16% or ferritin ≤20 (women) or 30 (men) µg/L, or ≤100 µg/L in the case of systemic inflammation. Apparent exacerbation was an exclusion criterion. We included 165 patients (78 women), mean age­31.1 ± 8.9 years. ID prevalence was 44.2%. ID was significantly associated with female gender (58.9% vs. 38%), lower age (29.4 ± 8.5 vs. 32.5 ± 9.1), lower body mass index (20.5 ± 2.2 vs. 21.3 ± 2.5), and Pseudomonas aeruginosa colonization (70.8% vs. 55.1%). Diabetes mellitus, antiacid drug use and low pulmonary function were more frequent in patients with ID with no statistical significance. The use of CFTR correctors was not associated with ID. In the multivariate analysis, ID was associated with female gender (OR 2.64, CI95% 1.31−5.31), age < 30 years (OR 2.30, CI95% 1.16−4.56), and P. aeruginosa (OR 2.09, CI95% 1.04−4.19).

Implementation of Model-Based Dose Adjustment of Tobramycin in Adult Patients with Cystic Fibrosis.

Therapeutic drug monitoring (TDM) of tobramycin is widely performed in patients with cystic fibrosis (CF), but little is known about the value of model-informed precision dosing (MIPD) in this setting. We aim at reporting our experience with tobramycin MIPD in adult patients with CF. We analyzed data from adult patients with CF who received IV tobramycin and had model-guided TDM during the first year of implementation of MIPD. The predictive performance of a pharmacokinetic (PK) model was assessed. Observed maximal (Cmax) and minimal (Cmin) concentrations after initial dosing were compared with target values. We compared the initial doses and adjusted doses after model-based TDM, as well as renal function at the beginning and end of therapy. A total of 78 tobramycin courses were administered in 61 patients. After initial dosing set by physicians (mean, 9.2 ± 1.4 mg/kg), 68.8% of patients did not achieve the target Cmax ≥ 30 mg/L. The PK model fit the data very well, with a median absolute percentage error of 4.9%. MIPD was associated with a significant increase in tobramycin doses (p < 0.001) without significant change in renal function. Model-based dose suggestions were wellaccepted by the physicians and the expected target attainment for Cmax was 83%. To conclude, the implementation of MIPD was effective in changing prescribing practice and was not associated with nephrotoxic events in adult patients with CF.

Inflammation of Unknown Origin: Evaluation and Prognosis of 57 Cases.

(1) Background: there are few studies on the inflammation of unknown origin (IUO). We sought to determine the etiologies and prognosis of IUO, as well as the contribution of complementary examinations. (2) Methods: this retrospective study analyzed patients meeting the Vanderschueren's criteria in the Hospices Civils de Lyon from 2005 to 2020. (3) Results: a total of 57 patients (mean age: 67 years; interquartile range: 55-79) were included. Final diagnoses were made for 26 (46%) patients. Non-infectious inflammatory diseases were the most common diagnoses (13/26, 50%), followed by neoplasms (10/26, 38%; 8/10 hematological malignancies), infections (2/26, 8%), and miscellaneous causes (1/26, 4%). Moreover, 18-FDG-PET/CT was contributory in 12/42 cases. Anti-neutrophil cytoplasmic antibodies, serology, temporal biopsies, and bone marrow aspirates were contributory in 3/41, 1/57, 5/23, and 3/19 cases, respectively. At last follow-up (mean follow-up duration: 48 months), 8/31 undiagnosed patients were cured (five received an empirical treatment), and 5/31 died (one death was related to the empirical treatment). (4) Conclusion: more than half of the IUO remained undiagnosed. Non-infectious inflammatory diseases and hematological malignancies were the most common etiologies. Moreover, 18-FDG-PET/CT had the highest diagnostic value. Most IUO without final diagnosis persisted. The role of empirical treatments remains to be explored.

A formalized transition program for cystic fibrosis: A 10-year retrospective analysis of 97 patients in Lyon.

INTRODUCTION: The prognosis of people diagnosed with cystic fibrosis (CF) has dramatically improved over the past decade in France, largely due to advances in CF care management, including an emphasis on chronic maintenance medications. Currently, the majority of French CF patients are adults, which means that they went through a transition process from receiving care at a pediatric CF center to receiving care at an adult CF center. To determine the impact of the transfer on clinical evolution, we report the transition procedure of our CF center in Lyon. MATERIALS AND METHODS: From January 2006 to December 2016, 97 CF patients underwent a standardized process of transitioning from the pediatric to the adult CF center in Lyon. We compared the clinical evolution of these patients during three periods, starting the year before transition and ending the year after transition. Clinical data taken into account were forced expiratory volume in 1 s (FEV1 in liters), body mass index (BMI in kg/m2 ), pulmonary colonization, number of antibiotic courses, number of days of hospitalization per year, and outpatient visits per year. RESULTS: No significant differences were observed between respiratory and nutritional status, respiratory microbiome, number of antibiotic courses, or number of hospitalizations or visits when comparing the threeperiods of observation around transition (the year before, the first year after, and the second year after transfer). CONCLUSION: The standardized transition procedure used in Lyon is associated with the clinical stability of our CF patients.

Risk factors for nontuberculous mycobacterial isolation in patients with cystic fibrosis: A meta-analysis.

BACKGROUND: To better understand the mechanisms of infection with nontuberculous mycobacteria (NTM) in patients with cystic fibrosis (CF), we explore different risk factors associated with NTM positivity in a meta-analysis. METHODS: Studies published before 31 July 2019 were selected from MEDLINE. Combined odds ratios (ORs) were calculated by pooling the ORs of each study. The weighted mean difference (WMD) was used for continuous numerical measurements. Summary data were pooled using fixed- or random-effects models according to the presence of heterogeneity (P < .1 or I2 > 50%). RESULTS: Nineteen studies with a total of 23 418 patients, of whom 1421 (6%) were diagnosed as NTM positive, were included. Older age was significantly associated with NTM positivity (WMD = 2.12, 95% confidence interval [CI]: 1.11-3.13; P < .01, fixed-effects model). The OR for Staphylococcus aureus colonization was 1.66 (95% CI: 1.21-2.26; P = .001) in 11 studies (8091 patients), the OR for Aspergillus fumigatus colonization was 3.59 (95% CI: 3.05-4.23; P < .001) in 11 studies (20 480 patients), and the OR for Stenotrophomonas maltophilia colonization was 3.41 (95% CI: 2.66-4.39; P < .01) in seven studies (14 935 patients). Oral corticosteroids were significantly associated with NTM positivity (OR = 1.98, 95% CI: 1.24-3.16; P < .01, 6 studies, 1936 patients). No other factor showed a significant association. CONCLUSION: Older age, S. aureus, S. maltophilia, and A. fumigatus chronic colonization, and oral corticosteroids were significantly associated with an increased risk of NTM positivity. CF patients with more severe conditions should be closely monitored for NTM.

Pregnancy outcome in women with cystic fibrosis and poor pulmonary function.

BACKGROUND: To investigate how poor pre-gestational pulmonary function influenced pregnancy outcome and clinical status evolution in women with cystic fibrosis. METHODS: Pregnancies in women without lung transplantation with a first delivery reported to the French cystic fibrosis registry between 2000 and 2012 were identified. Pregnancy outcomes and clinical trends (body mass index - BMI, and pulmonary function) over a 4-year follow-up in women with poor pre-gestational pulmonary function, defined as forced expiratory volume (FEV1) ≤ 50%, were compared to those in women with FEV1 ˃ 50%. RESULTS: A total of 149 women had a first delivery and 36 (24.2%) of these had pre-gestational FEV1 ≤ 50%. There was no significant difference in age or frequency of assisted conception between the 2 groups. The rate of cesarean section was significantly higher in women with FEV1 ≤ 50% (43.7% vs. 21.1%, p = .01). The frequency of preterm birth did not differ significantly between the two groups, but median infant birthweight was significantly lower in women with FEV1 ≤ 50% (2705 g; range: 650-3700 vs. 3044 g; range: 1590-3860, p = .003). Despite significantly lower FEV1 and BMI the year before pregnancy for women with poor pulmonary function, the decline in these parameters during the study period did not differ significantly between the two groups. CONCLUSION: Poor pre-gestational pulmonary function in women with cystic fibrosis was associated with a higher rate of cesarean section and a clinically significant impact on fetal growth, but was not associated with more important pulmonary and nutritional decline over the study period.

Late-onset combined immune deficiency: a subset of common variable immunodeficiency with severe T cell defect.

BACKGROUND: Common variable immunodeficiency (CVID) is a primary immune deficiency defined by defective antibody production. In most series, a small proportion of patients present with opportunistic infections (OIs). METHODS: The French DEFI study has enrolled patients with primary hypogammaglobulinemia and allows a detailed clinical and immunologic description of patients with previous OIs and/or at risk for OIs. RESULTS: Among 313 patients with CVID, 28 patients (8.9%) presented with late-onset combined immune deficiency (LOCID), defined by the occurrence of an OI and/or a CD4(+) T cell count <200 x 10(6) cells/L, and were compared with the remaining 285 patients with CVID. The patients with LOCID more frequently belonged to consanguineous families (29% vs 8%; P = .004). They differed from patients with CVID with a higher prevalence of splenomegaly (64% vs 31%), granuloma (43% vs 10%), gastrointestinal disease (75% vs 42%), and lymphoma (29% vs 4%). Even on immunoglobulin substitution, they required more frequent antibiotics administration and hospitalization. Lymphocyte counts were lower, with a marked decrease in CD4(+) T cell counts (158 x 10(6) vs 604 x 10(6) cells/L; P < .001) and a severe defect in naive CD45RA(+)CCR7(+)CD4(+) T cell counts (<20% of total CD4(+) T cells in 71% of patients with LOCID vs 37% of patients with CVID; P = .001). The CD19(+) B cell compartment was also significantly decreased (20 x 10(6) vs 102 x 10(6) cells/L; P < .001). CONCLUSIONS: LOCID differs from classic CVID in its clinical and immunologic characteristics. Systematic T cell phenotype may help to discriminate such patients from those with CVID. Identification of this phenotype should result in a more fitted diagnostic and therapeutic approach of infections and could provide insights for genetic diagnosis.

Is pegfilgrastim safe and effective in congenital neutropenia? An analysis of the French Severe Chronic Neutropenia registry.

AIMS: To examine the efficacy and safety of pegfilgrastim in patients with congenital neutropenia (CN). METHODS: Seventeen patients enrolled in the French Severe CN Register received pegfilgrastim. RESULTS: Median age at pegfilgrastim introduction was 19.1 years (range 3.9-52.3 years). In 14 cases pegfilgrastim replaced GCSF (filgrastim or lenograstim), after a median of 6.9 years of GCSF therapy. The dose of pegfilgrastim was usually one full vial per injection (except in five children, who received 1/6 to 1/2 a vial), resulting in a dose of between 50 and 286 microg/kg. The pegfilgrastim schedule ranged from two injections every 7 days to one injection every 30 days, with treatment-free periods. The median interval between the first and last dose of pegfilgrastim was 0.8 years (0.01-4.1 years). The absolute neutrophil count tended to increase more strongly on pegfilgrastim than on GCSF, but the difference was not statistically significant. During pegfilgrastim therapy, a severe infection occurred in two patients and recurrent ENT infections in two other patients. Bone pain was reported by nine patients, anemia and thrombocytopenia occurred in one patient (WHO grade III), chronic urticaria occurred in one patient (WHO grade III), and a single pegfilgrastim injection was followed by respiratory distress and death 15 days later in a patient with GDSIb. At the last update, 10 patients had stopped receiving pegfilgrastim and seven patients were still receiving pegfilgrastim. CONCLUSION: Compared to conventional GCSF, pegfilgrastim is more difficult to use in congenital neutropenia, with more frequent adverse events and sometimes poor efficacy.