Sai Yin Ho

Waist to stature ratio is more strongly associated with cardiovascular risk factors than other simple anthropometric indices

PURPOSE To determine which is the best anthropometric index among body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and waist to stature ratio (WSR) in relation to cardiovascular risk factors. METHODS A representative sample of 2895 Hong Kong Chinese aged 25 to 74 years received medical examinations in 1995 and 1996. Anthropometric indices and cardiovascular risk factors in blood were measured, and partial correlation and Receiver Operator Characteristic (ROC) curves were used in analysis. RESULTS Among 11 cardiovascular risk factors in partial correlation analysis, including ties WSR had the highest r in 6 in men, and 5 in women; followed by WC with 4 in men and 6 in women. In ROC analyses of 21 risk factors and health conditions, the area under curve (AUC) of WSR was the largest for most (13 of 21) factors in men and 10 in women; followed by WHR with 14 in women but only 5 in men. The optimal WSR cutoff value was 0.48 for both men and women. CONCLUSIONS WSR is the best simple anthropometric index in predicting a wide range of cardiovascular risk factors and related health conditions. A simple message that ones waist circumference should not exceed half the stature is recommended for the public.

Mortality and smoking in Hong Kong : case-control study of all adult deaths in 1998

Abstract Objective: To assess the mortality currently associated with smoking in Hong Kong, and, since cigarette consumption reached its peak 20 years earlier in Hong Kong than in mainland China, to predict mortality in China 20 years hence. Design: Case-control study. Past smoking habits of all Chinese adults in Hong Kong who died in 1998 (cases) were sought from those registering the death. Setting: All the death registries in Hong Kong. Participants: 27 507 dead cases (81% of all registered deaths) and 13 054 live controls aged ≥35 years. Main outcome measures: Mortality from all causes and from specific causes. Results: In men aged 35-69 the adjusted risk ratios (and 95% confidence intervals) comparing smokers with non-smokers were 1.92 (1.70 to 2.16) for all deaths, 2.22 (1.94 to 2.55) for neoplastic deaths, 2.60 (2.10 to 3.21) for respiratory deaths (including tuberculosis, risk ratio 2.54), and 1.68 (1.43 to 1.97) for vascular deaths (each P<0.0001). In women aged 35-69 the corresponding risk ratios were 1.62 (1.40 to 1.88) for all deaths, 1.60 (1.33 to 1.93) for neoplastic deaths, 3.13 (2.21 to 4.44) for respiratory deaths, and 1.55 (1.20 to 1.99) for vascular deaths (each P<0.001). If these associations with smoking are largely or wholly causal then, among all registered deaths at ages 35-69 in 1998, tobacco caused about 33% (2534/7588) of all male deaths and 5% (169/3341) of all female deaths (hence 25% of all deaths at these ages). At older ages tobacco seemed to be the cause of 15% (3017/20 420) of all deaths. Conclusions: Among middle aged men the proportion of deaths caused by smoking is more than twice as big in Hong Kong now (33%) as in mainland China 10 years earlier. This supports predictions of a large increase in tobacco attributable mortality in China as a whole. What is already known on this topic China, with 20% of the worlds population, smokes 30% of the worlds cigarettes. Men smoke most, and the proportion of male deaths at ages 35-69 attributable to tobacco has been predicted to rise over the next few decades from 13% (in 1988) to about 33% In Hong Kong cigarette consumption reached its peak 20 years earlier than in mainland China, so the epidemic of male deaths from tobacco should now be at a more advanced stage What this study adds In the general population of Hong Kong in 1998 tobacco caused about 33% of all male deaths at ages 35-69 plus 5% of all female deaths, and hence 25% of all deaths at these ages In the male smokers tobacco caused about half of all deaths at ages 35-69 The hazards now seen in Hong Kong foreshadow a substantial increase in tobacco deaths among middle aged men in mainland China over the next few decades if current smoking patterns persist

Metabolic syndrome increases all‐cause and vascular mortality: the Hong Kong Cardiovascular Risk Factor Study

Objective  The metabolic syndrome has been associated with increased mortality in some Caucasian populations, but data in Asian populations are not available. We present data describing the association of the metabolic syndrome with mortality.

Health-related physical fitness and weight status in Hong Kong adolescents

BackgroundThis study was designed to investigate the relation between health-related physical fitness and weight status in Hong Kong adolescents.Methods3,204 students aged 12-18 years participated in the Hong Kong Student Obesity Surveillance (HKSOS) project in 2006-2007. Anthropometric measures (height, weight) and health-related fitness (push-up, sit-up, sit-and-reach, 9-minute run) were assessed. Body mass index (BMI) was computed to classify participants into normal weight, underweight (Grade I, II/III), overweight, and obese groups. The associations of health-related physical fitness with BMI and weight status were examined by partial correlation coefficients and analysis of covariance, respectively.ResultsMore boys than girls were overweight or obese (18.0% vs 8.7%), but more girls than boys were underweight (22.3% vs 16.7%). Boys performed significantly (P < 0.001) better in sit-up (38.8 vs 31.6 times/min) and 9-minute run (1632.1 vs 1353.2 m), but poorer in sit-and-reach (27.4 vs 32.2 cm) than girls. All four physical fitness tests were significantly positively correlated with each other in both sexes, and BMI was only weakly correlated with sit up and sit-and-reach tests in boys. Decreasing performance (P for trend < 0.05) was observed from normal weight to overweight and obese for push-up, sit-up, and 9-minute run in both sexes. From normal weight to Grade I and Grade II/III underweight, decreasing performance (P for trend < 0.05) for sit-up and sit-and-reach in both sexes and for push-up in boys was observed.ConclusionsThe relations between BMI and health-related physical fitness in adolescents were non-linear. Overweight/obese and underweight adolescents had poorer performance in push-up and sit-up tests than normal weight adolescents. Different aspects of health-related physical fitness may serve as immediate indicators of potential health risks for underweight and overweight adolescents.

Mortality associated with passive smoking in Hong Kong.

Passive smoking can cause death from lung cancer and coronary heart disease, but there is little evidence for associations with other causes of death in never smokers. A recent study showed increased all cause mortality with exposure to secondhand smoke at home but did not examine associations with specific causes of death and dose-response relations.1 We have published estimates of the mortality attributable to active smoking in Hong Kong2 and now present the related findings on passive smoking at home. Details of the sample selection and data collection have been reported.2 Each person who reported a death in 1998 at four death registries was given a questionnaire which asked about the lifestyle 10 years earlier of the decedent and of a living person about the same age who was well known to the informant. Passive smoking was identified in the interview with the question, “Ten years ago, in about 1988, excluding the decedent/control, how many persons who lived with the decedent/control smoked?” Decedents or …

Comprehensive smoke-free legislation and displacement of smoking into the homes of young children in Hong Kong.

Objective To investigate the effect of comprehensive smoke-free legislation in 2007 on the exposure of children to secondhand smoke (SHS) in Hong Kong. Methods Two cross-sectional questionnaire surveys were conducted, before (2006) and after (2008) the implementation of smoke-free legislation, among primary 2–4 students (equivalent to US grades 2–4) from 19 and 24 randomly selected schools, respectively. Adjusted ORs for SHS exposure at home and outside home post-legislation compared with pre-legislation were calculated. The strength of the association between SHS exposure and respiratory symptoms in each survey was used as an indirect indicator of the intensity of exposure. Results Among 3243 and 4965 never smoking students in the 2006 and 2008 surveys, the prevalence of SHS exposure in the past 7 days increased both at home (from 10.2% to 14.1%) and outside home (from 19.8% to 27.2%). Post-legislation, students were 56% more likely (p<0.01) to report SHS exposure at home coupled with an insignificantly stronger association between SHS exposure and respiratory symptoms. Similarly, students were 60% more likely (p<0.001) to report SHS exposure outside home in 2008, but the association between SHS exposure and respiratory symptoms became insignificantly weaker. Parental smoking rates were similar before and after legislation. Conclusions The prevalence of exposure to SHS at home and outside home have both increased among primary school students in Hong Kong post-legislation. Comprehensive smoke-free legislation without strong support for smoking cessation might have displaced smoking into the homes of young children.

Socioeconomic disparities in air pollution-associated mortality

This study aimed to determine whether individuals with lower socioeconomic status (SES) were more susceptible to the acute effects of ambient air pollution than those with higher SES. We included 24,357 Hong Kong Chinese aged 30 or above who died of natural causes in 1998. Information on individual socioeconomic characteristics was obtained by interviewing proxy informants with a standardized questionnaire in all four death registries. Individual SES was indicated by three measures: type of housing, occupational group and education attainment. Poisson regression was performed to assess the short-term effects of ambient air pollution measured by PM(10), NO(2), SO(2) and O(3) on mortality for each SES group. The differences in the effects between SES groups were estimated by the interaction between air pollution and SES. We found that PM(10) and NO(2) were associated with greater risk of mortality on people living in public rental housing than in private housing. The effects of all four pollutants were significantly greater in blue-collar workers than the never-employed and white-collar groups (p<0.05). However, we found no compelling evidence of effect modification by education attainment. Our results provide new evidence on the role of individuals SES as effect modifiers of the short-term effects of air pollution on mortality. The reduction of risks associated with air pollution for socially disadvantaged populations should be a high priority in public health and environmental policies.

Reliable and valid NEWS for Chinese seniors: measuring perceived neighborhood attributes related to walking.

BackgroundThe effects of the built environment on walking in seniors have not been studied in an Asian context. To examine these effects, valid and reliable measures are needed. The aim of this study was to develop and validate a questionnaire of perceived neighborhood characteristics related to walking appropriate for Chinese seniors (Neighborhood Environment Walkability Scale for Chinese Seniors, NEWS-CS). It was based on the Neighborhood Environment Walkability Scale - Abbreviated (NEWS-A), a validated measure of perceived built environment developed in the USA for adults. A secondary study aim was to establish the generalizability of the NEWS-A to an Asian high-density urban context and a different age group.MethodsA multidisciplinary panel of experts adapted the original NEWS-A to reflect the built environment of Hong Kong and needs of seniors. The translated instrument was pre-tested on a sample of 50 Chinese-speaking senior residents (65+ years). The final version of the NEWS-CS was interviewer-administered to 484 seniors residing in four selected Hong Kong districts varying in walkability and socio-economic status. Ninety-two participants completed the questionnaire on two separate occasions, 2-3 weeks apart. Test-rest reliability indices were estimated for each item and subscale of the NEWS-CS. Confirmatory factor analysis was used to develop the measurement model of the NEWS-CS and cross-validate that of the NEWS-A.ResultsThe final version of the NEWS-CS consisted of 14 subscales and four single items (76 items). Test-retest reliability was moderate to good (ICC > 50 or % agreement > 60) except for four items measuring distance to destinations. The originally-proposed measurement models of the NEWS-A and NEWS-CS required 2-3 theoretically-justifiable modifications to fit the data well.ConclusionsThe NEWS-CS possesses sufficient levels of reliability and factorial validity to be used for measuring perceived neighborhood environment in Chinese seniors. Further work is needed to assess its construct validity and generalizability to other Asian locations. In general, the measurement model of the original NEWS-A was generalizable to this study context, supporting the feasibility of cross-country and age-group comparisons of the effect of the neighborhood environment on walking using the NEWS-A as a tool to measure the perceived built environment.

Smoking, quitting and mortality in an elderly cohort of 56 000 Hong Kong Chinese

Background: Although the harms of smoking are well established, it is unclear how they extend into old age in the Chinese. Aim: To examine the relationship of smoking with all-cause and major cause-specific mortality in elderly Chinese men and women, respectively, in Hong Kong. Methods: Mortality by smoking status was examined in a prospective cohort study of 56 167 (18 749 men, 37 416 women) Chinese aged ⩾65 years enrolled from 1998 to 2000 at all the 18 elderly health centres of the Hong Kong Government Department of Health. Results: After a mean follow-up of 4.1 years, 1848 male and 2035 female deaths occured among 54 214 subjects (96.5% successful follow-up). At baseline, more men than women were current smokers (20.3% vs 4.0%) and former smokers (40.8% vs 7.9%). The adjusted RRs (95% CI) for all-cause mortality in former and current smokers, compared with never smokers, were 1.39 (1.23 to 1.56) and 1.75 (1.53 to 2.00) in men and 1.43 (1.25 to 1.64) and 1.38 (1.14 to 1.68) in women, respectively. For current smokers, the RRs (95% CI) for all-cause mortality were 1.59 (1.39 to 1.82), 1.72 (1.48 to 2.00) and 1.84 (1.43 to 2.35) for daily consumption of 1–9, 10–20 and >21 cigarettes, respectively (p for trend <0.001). RRs (95% CI) were 1.49 (1.30 to 1.72) and 2.20 (1.88 to 2.57) in former and current smokers for all deaths from cancer, and 1.24 (1.04 to 1.47) and 1.57 (1.28 to 1.94) for all cardiovascular deaths, respectively. Quitters had significantly lower risks of death than current smokers from all causes, lung cancer, all cancers, stroke and all cardiovascular diseases. Conclusions: In old age, smoking continues to be a major cause of death, and quitting is beneficial. Smoking cessation is urgently needed in rapidly ageing populations in the East.

The Short Form-12 Health Survey was a valid instrument in Chinese adolescents

OBJECTIVE To evaluate the construct validity of the standard Chinese Short Form (SF)-12v2 in adolescents. STUDY DESIGN AND SETTING Data collected from the Hong Kong Student Obesity Surveillance project conducted in 2006-2007 were used. The standard Chinese SF-12v2 was first evaluated against clinical criteria previously used for the evaluation of SF-12 or SF-36. The data were then randomly split into training and validation halves for exploratory and confirmatory factor analyses, respectively. RESULTS A total of 31,357 adolescents with mean age of 14.8 years (standard deviation=1.9; range=11.0-18.9) were included. The standard Chinese SF-12v2 effectively distinguished groups differing in doctor-diagnosed health problems, self-reported illnesses in the past 30 days, gender, perceived health in the past 3 months, and health compared with that 12 months back. The mental health scale had low internal consistency (Cronbachs alpha=0.34). The exploratory factor analysis was influenced by method effects, but confirmatory factor analysis confirmed the hypothesized latent structure and the one-factor structure of the SF-12v2, providing fit indices within acceptable limits. CONCLUSION The two components and a single general health component of the standard Chinese SF-12v2 are appropriate health indicators for Chinese adolescents.