Introduction: Several population-based epidemiologic studies have been conducted to evaluate the incidence of oral clefts in different ethnicities in the United States and other countries. The largest studies were performed in white (non-Hispanic) subjects. The highest incidence rates have been reported in Asians and Native Americans.
Material and methods: We performed a retrospective longitudinal analysis of the California Office of Statewide Health Planning and Development patient discharge database from 1995 to 2010. We identified the yearly number of live births and the number of patients diagnosed with cleft palate or cleft lip with or without palate. We also stratified the number of live births and the incidence of clefts based on ethnic backgrounds. We studied the trend in the incidence rates among different ethnicities in the period between 1995 and 2010. We identified and analyzed data from 3 main groups of patients: those with any cleft disease (AC), isolated cleft palate (CP), and cleft lip with or without cleft palate (CLP).
Results: Our database shows a total number of 8,043,393 live births included in the study. The calculated incidence rates for the white (Non-Hispanic) population are 16.2 with AC, 7.6 with CP, and 8.67 with CLP. Rates for the Hispanic population are 12.26 with AC, 4.79 with CP, and 7.5 with CLP. Rates for Asian/Pacific Islanders are 11.57 with AC, 4.9 with CP, and 6.68 with CLP. Rates for the African American population are 8.9 with AC, 4.1 with CP, and 6.7 with CLP. Rates for the Native American population are 8.15 with AC, 2.1 with CP, and 6 with CLP. We also noticed a declining trend in the incidence rates of AC, CP, and CLP over the period of the study between 1995 and 2010.
Discussion: Our results suggest different incidence rates among different ethnicities. We found the highest rates for any oral cleft, isolated cleft palate, and cleft lip with and without palate in the white (non-Hispanic) population. The declining incidence rates during the period of the study (15 years) could be attributed to environmental, demographic, or gene pool factors. However, further studies are needed to investigate this finding.