Population prevalence of diagnosed primary immunodeficiency diseases in the United States

Although health surveys are routinely used to estimate the population incidence and prevalence of many chronic and acute conditions in the U.S. population, they have infrequently been used for "rare" conditions such as primary immunodeficiency diseases (PID). Accurate prevalence measures are needed to separate the truly rare condition from those that primary care doctors are likely to see in their practices today, if early diagnosis and treatment are to be achieved. A national probability sample of 10,000 households was sampled by random digit dialing and screened by telephone to identify how many of the nearly 27,000 household members had been diagnosed with a PID. A total of 23 household members in 18 households were reported with a specific diagnosis for PID (CVID, IgA, IgG, XLA, SCID, CGD), whereas additional cases were reported as a PID without a confirmatory diagnosis. These findings suggest a population prevalence of diagnosed PID in the United States at approximately 1 in 1,200 persons. Diagnoses of PID in the United States are far more common than suggested in the literature.