Oscillometric 24-h ambulatory blood pressure reference values in Hong Kong Chinese children and adolescents.

OBJECTIVES: We aimed to establish community-based normal reference values of 24-h ambulatory blood pressure monitoring (ABPM) for Chinese children and adolescents. Furthermore, we investigated how excluding overweight children affects BP percentiles and compared them with German references. METHODS: In this territory-wide cross-sectional prospective cohort study, 1445 Hong Kong Chinese children and adolescents aged 8-17 years with body height between 119 and 185 cm were recruited. Their ABPM assessment was performed using validated arm oscillometric recorders (A&D TM-2430) and complied with American Heart Association's recommendations. The reference tables were constructed using the LMS method to normalize skewed distribution of ABP data to sex and age or height. RESULTS: The ambulatory BP was higher among boys and the difference between boys and girls progressively widened with age. An increasing trend in daytime and night-time SBP and DBP with age and height was observed in both sexes. The age-specific and sex-specific 95th percentiles from nonoverweight children (n=1147; 79%) were lower than the whole cohort by up to 2.5 and 1 mmHg for SBP and DBP, respectively. In comparison, our overall and nonoverweight reference standards were generally higher than corresponding German references. CONCLUSION: The study provides ambulatory BP standards for Chinese children, with sex-related age-specific and height-specific percentiles. Further longitudinal studies are required for investigating its clinical utility in Chinese.

Prevalence and risk factors for hypertension in Hong Kong Chinese adolescents: waist circumference predicts hypertension, exercise decreases risk.

PURPOSE: To determine the prevalence, risk factors for and patterns of hypertension in Chinese adolescents based on a territory-wide school based screening programme in Hong Kong. METHODS: Cross-sectional anthropometric and oscillometric blood pressure (BP) measurements and lifestyle information were obtained as part of a growth survey of students from randomly selected secondary schools in Hong Kong. Those with blood pressure ≥ 95th centile were screened a second or third time. Hypertension is defined as elevated blood pressure on three separate occasions. The independent effects of age, sex, body mass index, high waist circumference (≥ 85th centile), sleep duration, family history of hypertension and frequency of exercise on hypertension were explored by multivariate analysis. RESULTS: Among the 6193 students screened, the prevalence of elevated blood pressure on the first, second and third screens was 9.54%, 2.77% and 1.44% respectively. Hypertension was more likely to be systolic. High waist circumference (≥ 85th centile) was independently associated with a higher risk of hypertension (adjusted OR 2.4), while exercising twice or more per week was protective (adjusted OR 0.28). CONCLUSIONS: The prevalence of hypertension in Hong Kong Chinese adolescents is 1.44%. The current study shows high waist circumference is a predictor of hypertension in adolescents, while increased physical activity is a protective factor. Incorporating waist circumference into screening protocols may increase the sensitivity of cardiovascular risk stratification. Healthcare providers should be strong advocates helping to prevent obesity and promote physical activity in adolescents and children.

A cluster of chilblains in Hong Kong.

OBJECTIVE: To report a recent clustering of chilblain cases in Hong Kong. DESIGN: Case series. SETTING: A regional hospital and a social hygiene clinic in the New Territories West, Hong Kong. PATIENTS: Patients with a clinical diagnosis of chilblains in February 2008. RESULTS: Eleven patients with chilblains were identified; seven (64%) gave an antecedent history of prolonged exposure to cold. They all presented with erythematous or dusky erythematous skin lesions affecting the distal extremities, especially fingers and toes. Laboratory tests revealed elevated antinuclear antibodies titres in two, positive rheumatoid factor in two, presence of cold agglutinins in one, and a raised anti-DNA titre (>300 IU/mL) in one. Skin biopsies were performed in six patients, four of them showed typical histopathological features of chilblains. In the patient with systemic lupus erythematosus, features of vasculitis were suspected, and in the one with pre-existing juvenile rheumatoid arthritis, there were features of livedo vasculitis. In 10 (91%) of the patients, the skin lesions had resolved when they were last assessed (at the end of March 2008), but had persisted in the patient who had pre-existing systemic lupus erythematosus. CONCLUSION: The recent clustering of chilblains was possibly related temporally to the prolonged cold weather at the end of January to mid-February. In our series, most of the patients developed chilblains as an isolated condition and resolved spontaneously within a few weeks. Laboratory tests and skin biopsies for chilblains are not necessary, unless the condition persists, the diagnosis in doubt or an underlying systemic disease is suspected.