Infection Phenotypes Among Patients with Primary Antibody Deficiency Mined from a US Patient Registry

Purpose: Primary immunodeficiency disorders (PIDs) affect immune system development and/or function, increase infection susceptibility, and cause dysregulation or both. Recognition of PID requires assessment about the normal state of infection frequency and microbiology. To help clarify infection characteristics, we use data mined from the US Immunodeficiency Network (USIDNET) registry among primary antibody deficiency (PAD) patients before diagnosis. Methods: We analyzed PAD patient data from the USIDNET registry prior to ultimate diagnosis. Our analysis included basic descriptive statistics for 8 major infection subtypes and significance testing for comparing infection rate by specific organisms across 7 distinct PAD subtypes. Results: Of 2038 patients reviewed, 1259 (61.8%) had infections reported prior to diagnosis. Most (77.4%) had four or less reported infections prior to diagnosis; however, some suffered up to 16 infections. Infection patterns differed across the PAD subtypes. Patients with agammaglobulinemia differed significantly from patients with all other forms of PAD studied in at least one infection category, whereas patients with CVID differed from 3 other PAD categories in at least one infection category. Patterns of infections in patients with hypogammaglobulinemia, specific antibody deficiency, and transient hypogammaglobulinemia were less unique. For each of the infection types, bacteria were the most prevalent cause of disease. Conclusions: Our data shows that distinct subtypes of PAD display unique infection patterns. We also show that patients with agammaglobulinemia suffer more invasive infections and differ most significantly from all other forms of PAD studied. Our analysis has broad implications about infection surveillance, progression, and vulnerability by PAD subtype.