An estimate of the prevalence of Down's Syndrome in Hong Kong

Abstract

BACKGROUND: With improved medical care, people with Down's syndrome are now living longer. Given the increased healthcare needs of this population throughout life, it is important for the planning of healthcare services to know the age-specific prevalence of this condition. Currently, there is no national birth defects registry in Hong Kong and the prevalence of Down's syndrome in Hong Kong is unknown. METHOD: The CDARS system was used to identify all people who had used any Hong Kong Hospital Authority service between 1995 and 2012 and had an ICD9 diagnosis code of 758.0 – Down's syndrome in any diagnosis field. Duplicates were removed and those who had died before 31/12/10 or were born after 31/12/10 were excluded. The remaining 2120 patients were stratified by gender and 5 year age group. Age and gender stratified population counts from the Hong Kong Census 2011 were used as the denominator. RESULTS: The overall prevalence of Down's syndrome in Hong Kong is 3.00 per 10,000 population (95%CI 2.87, 3.12). Prevalence is higher in males with an overall prevalence of 3.38 per 10,000 (95%CI 3.18, 3.59) compared with 2.66 per 10,000 (95%CI 2.50, 2.83) for females. The difference between genders is most marked in the younger age groups. Prevalence is highest amongst the under 5s at 9.95 per 10,000 population (95%CI 8.71, 11.19) and decreases with age to 5.74 per 10,000 population (95%CI 5.04, 6.43) in the 20-25 year age group and 1.99 per 10,000 population (95%CI 1.65, 2.34) in the 45-50 year age group. The prevalence is 0 per 10,000 population by age 80 and over. Almost half (47.5%) of the Down's syndrome population in Hong Kong is under 20 years of age. CONCLUSION: This study provides an initial estimate of the age and gender-specific prevalence of Down's syndrome in Hong Kong. The results are important for planning Hospital Authority services for this population of people with Down's syndrome, who are known to have increased healthcare needs.