Primary immunodeficiency diseases in Australia and New Zealand.

INTRODUCTION: Despite rapid developments in the science of primary immunodeficiency diseases (PID), population characteristics and the burden of disease are poorly characterized. Aggregated data on PID via patient registries are a key component of the public health response. The web-enabled Australasian Society of Clinical Immunology and Allergy PID Register was designed and implemented to address gaps in knowledge of PID. METHODS: The register provided a cumulative, cross-sectional survey of PID patients in Australia and New Zealand via an online, single time point, center-based, voluntarily recalled, and patient-consented questionnaire. RESULT: Eighty-eight centers reported 1,209 patients across 56 separate PID syndromes. The study prevalence (cases per 100,000 population) was 5.6 for Australia, 12.4 for the state of South Australia, and 4.9 for Australia and New Zealand combined. Predominately antibody deficiency syndromes accounted for 77% of patients. Common variable immunodeficiency was the most common diagnosis. Patients were geographically dispersed with 80% of centers reporting caseloads of less than 20 patients. Potentially preventable complications of disease were common. Immunoglobulin replacement therapy was used in 30 conditions with 26.5% of the total recipients having antibody deficiency disorders with normal serum IgG. CONCLUSION: PID in Australia and New Zealand are prevalent, clinically diverse, geographically dispersed, and are characterized by high rates of potentially preventable morbidity and resource utilization. A public health focus on PID is required, including strategies to correct disparities in access to care, improve molecular diagnostics and reduce preventable complications of disease. Further studies in antibody deficiency syndromes with normal serum IgG are required.