Estimation of the number of people with Down syndrome in the United States

Purpose: An accurate accounting of persons with Down syndrome (DS) has remained elusive because no population-based registries exist in the United States. The purpose of this study was to estimate this population size by age, race, and ethnicity. Methods: We predicted the number of people with DS in different age groups for different calendar years using estimations of the number of live births of children with DS from 1900 onward and constructing DS-specific mortality rates from previous studies. Results: We estimate that the number of people with DS living in the United States has grown from 49,923 in 1950 to 206,366 in 2010, which includes 138,019 non-Hispanic whites, 27,141 non-Hispanic blacks, 32,933 Hispanics, 6,747 Asians/Pacific Islanders, and 1,527 American Indians/American Natives. Population prevalence of DS in the United States, as of 2010, was estimated at 6.7 per 10,000 inhabitants (or 1 in 1,499). Conclusion: Until 2008, DS was a rare disease. In more recent decades, the population growth of people with DS has leveled off for non-Hispanic whites as a consequence of elective terminations. Changes in childhood survival have impacted the age distribution of people with DS, with more people ill their fourth, fifth, and sixth decades of life.