To determine expected population prevalence of the immune-related comorbidities included in the OCGAS medical questionnaire, a review of United States data was carried out using PubMed and Medline databases and annual reports published by the Centers for Disease Control and Prevention. Keywords and subject headings were used to identify studies of prevalence or incidence. Both population-based cross-sectional and cohort studies were included, with data based on self-report surveys, where available. When national data were unavailable, North American data were used. Broad ranges were used to include all frequencies and confidence intervals described in identified reports. Where incidence only was available, prevalence was determined by multiplying by the cohort's mean age, 27.8 years. These conservative lifetime prevalence values derived from incidence are therefore likely to be overestimates. Where indicated in Supplementary Table S2, under- or nonreporting of diseases limited the utility of available data.
