Leukopenia

From January 1, 2010, to June 30, 2012, adults 18 years of age or older were enrolled at three hospitals in Chicago (John H. Stroger, Jr., Hospital of Cook County, Northwestern Memorial Hospital, and Rush University Medical Center) and at two in Nashville (University of Tennessee Health Science Center–Saint Thomas Health and Vanderbilt University Medical Center). We sought to enroll all eligible adults; therefore, trained staff screened adults for enrollment at least 18 hours per day, 7 days per week. Written informed consent was obtained from all the patients or their caregivers before enrollment. The study protocol was approved by the institutional review board at each participating institution and at the CDC. Weekly teleconferences, enrollment reports, data audits, and annual study-site visits were conducted to ensure uniform procedures among the study sites. Patients or their caregivers provided demographic and epidemiologic data, and medical charts were abstracted for clinical data. All the authors vouch for the accuracy and completeness of the data and analyses reported and for the fidelity of the study to the protocol. All the authors made the decision to submit the manuscript for publication.
Adults were eligible for enrollment if they were admitted to a study hospital on the basis of a clinical assessment by the treating clinician; resided in the study catchment area (see the Supplementary Appendix, available with the full text of this article at NEJM.org); had evidence of acute infection, defined as reported fever or chills, documented fever or hypothermia, leukocytosis or leukopenia, or new altered mental status; had evidence of an acute respiratory illness, defined as new cough or sputum production, chest pain, dyspnea, tachypnea, abnormal lung examination, or respiratory failure; and had evidence consistent with pneumonia as assessed by means of chest radiography by the clinical team within 48 hours before or after admission.
Patients were excluded if they had been hospitalized recently (<28 days for immunocompetent patients and <90 days for immunosuppressed patients), had been enrolled in the EPIC study within the previous 28 days, were functionally dependent nursing home residents,^{14 (link)} or had a clear alternative diagnosis (see the Supplementary Appendix). Patients were also excluded if they had undergone tracheotomy, if they had a percutaneous endoscopic gastrostomy tube, if they had cystic fibrosis, if they had cancer with neutropenia, if they had received a solid-organ or hematopoietic stem-cell transplant within the previous 90 days, if they had active graft-versus-host disease or bronchiolitis obliterans, or if they had human immunodeficiency virus infection with a CD4 cell count of less than 200 per cubic millimeter.^{10 (link)}

The NCI IBMFS cohort is an open retrospective/prospective cohort, established in January 2002, with approval from the NCI Institutional Review Board. Data reported here include individuals enrolled prior to December, 2007, with follow-up through to December, 2008. The protocol, NCI 02-C-0052 [NCT00056121] (http://www.marrowfailure.cancer.gov), was advertised by mailing to paediatric haematologists/oncologists, medical geneticists, and IBMFS family support groups. Voluntary enrollment by the family contact (usually a parent or proband; a proxy was used for deceased patients) began with a telephone interview. Discussion at a team meeting determined whether the proband met the criteria for the suspected syndrome or needed further testing. A Family History Questionnaire provided medical information about relatives. Written informed consent and medical record release forms were signed. Individual Information Questionnaires (medical history, cancer risk factors, etc.) were sent to the proband (or proxy) and first-degree relatives. Biannual follow-up was obtained on all participants. Cancer diagnoses were confirmed by medical record review. All participants were enrolled in the ‘Field Cohort.’ Those who visited the National Institutes of Health (NIH) Warren G. Magnuson Clinical Center were reassigned to the ‘Clinic Cohort.’ Families in the Clinic Cohort visited the NIH for 5 d, for thorough review of medical histories and physical examinations by haematologists and multiple subspecialists, as well as aetiologically-focused laboratory tests.
Participants were assigned to a specific syndrome according to standard criteria and confirmed by syndrome-specific tests where available (Alter, 2003 ). FA was diagnosed by abnormal chromosome breakage in peripheral blood lymphocytes, using both diepoxybutane and mitomycin C (Cervenka et al, 1981 (link); Auerbach et al, 1989 ). Skin fibroblasts were analysed when lymphocytes were normal but FA remained highly suspect (seeking evidence for haematopoietic mosaicism) (Alter et al, 2005 (link)). FA complementation group analyses were performed using retroviral correction (Chandra et al, 2005 (link)).
The clinical diagnosis of DC was made in individuals with components of the diagnostic triad (nail dystrophy, reticular pigmentation, and oral leucoplakia), or those with at least one other typical physical finding (Vulliamy et al, 2006 (link)), in association with marrow failure. We expanded the inclusion criteria to patients with marrow failure, any of the above physical parameters, and blood leucocyte subset telomere lengths below the first percentile of normal-for-age (Alter et al, 2007a (link)). We also classified as ‘DC’ probands and healthy family members who had pathogenic mutations in known DC genes, such as DKC1, TERC, TERT, and TINF2, including those with none of the typical physical findings (Savage & Alter, 2009 (link)).
The diagnosis of DBA was made in those with macrocytic pure red cell aplasia, and supported by finding increased red cell adenosine deaminase (Glader & Backer, 1988 (link)). Patients with SDS had neutropenia and exocrine pancreatic insufficiency, confirmed by detection of sub-normal levels of serum pancreatic trypsinogen and isoamylase (Ip et al, 2002 (link)).
All living affected individuals were specifically screened for all of the major IBMFS; genotyping was performed when possible (Ameziane et al, 2008 (link); Moghrabi et al, 2009 (link)). Affected individuals who had not received a transplant had bone marrow aspirations, biopsies and cytogenetic studies. Individuals who could not be classified as having a specific IBMFS were designated as ‘Others.’ Categories of ‘DC-like,’ ‘FA-like,’ and ‘SDS-like’ were used for individuals whose features initially suggested DC, FA, or SDS but who failed to meet diagnostic criteria. Severe bone marrow failure was defined as impaired haematopoiesis sufficiently severe to lead to bone marrow transplant (BMT) or death (Rosenberg et al, 2003 (link)); MDS required severe pancytopenia and dyspoietic morphology, with or without a cytogenetic clone (Alter et al, 2000 (link)).
Analyses used Microsoft Excel 11.0 (Microsoft, Redmond, WA, USA), Stata 10.1 (StataCorp, College Station, TX, USA), and MATLAB 2008b software (The MathWorks, Natick, MA, USA). The Kaplan-Meier product limit estimator was used to calculate actuarial survival probabilities by age and cumulative incidences in the absence of competing risks; subjects were censored at death (Kaplan & Meier, 1958 ). Subgroup survivals were compared using the log-rank test for equality of survivor functions. Cause-specific hazards and cumulative incidence curves accounting for competing risks were calculated as described previously (Rosenberg et al, 2003 (link)). The observed number of cancers was compared with the expected number (O/E ratio), based on general population incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program, adjusting for age, sex, race, and birth cohort (Ries et al, 2008 ). Sex ratios were examined using the binomial test of comparison with a male:female ratio of 1:1. Statistical tests were 2-sided, and P-values ≤0·05 were considered significant.

From January 1, 2010 to June 30, 2012, children <18 years old were enrolled in the EPIC study at Le Bonheur Children's Hospital (Memphis, TN), Monroe Carell Jr. Children's Hospital at Vanderbilt (Nashville, TN), and Primary Children's Hospital (Salt Lake City, UT). We sought to enroll all eligible children; thus trained staff screened for enrollment for at least 18 hours each day, 7 days each week. Written informed consent was obtained before enrollment. The study protocol was approved by the institutional review boards at each institution and the CDC. Weekly study teleconferences, required weekly enrollment reports, data audits, and annual site visits were conducted to ensure uniform procedures among sites.
Children were included if they 1) were admitted to one of the three study hospitals;2) resided in one of the 22 counties in the study catchment areas;3) had evidence of acute infection defined as reported fever or chills, documented fever or hypothermia, or leukocytosis or leukopenia; 4) had evidence of an acute respiratory illness defined as new cough or sputum production, chest pain, dyspnea, tachypnea, abnormal lung examination, or respiratory failure; and 5) had chest radiography consistent with pneumonia ≤72 hours of admission.
Children were excluded if they were recently hospitalized (<7 days for immunocompetent, <90 days for immunosuppressed), enrolled in the EPIC study <28 days earlier, resided in an extended care facility, had an alternative respiratory diagnosis, or were newborns who never left the hospital. Children with the following were excluded: tracheostomy, cystic fibrosis, cancer with neutropenia, solid organ or hematopoietic stem cell transplant ≤90 days earlier, active graft-versus-host-disease or bronchiolitis obliterans, or human immunodeficiency virus infection with CD4 cell count <200 cells/mm³ (or CD4%<14%).