Birth weight and adult cardiovascular risk factors using multiple birth status as an instrumental variable in the 1958 British Birth Cohort

BACKGROUND

Birth weight is classified as a risk factor for cardiovascular disease by the World Health Organization, but appropriate preventive interventions remain unclear because the observations have not been confirmed in experiments and appear to be contextually specific.

METHODS

Using 9452 participants of the 1958 British Birth Cohort at age 42years in 2000 (58% follow-up), we examined the credibility of multiple birth status as an instrumental variable (IV) for birth weight and, if appropriate, use it to obtain less confounded estimates of the associations of birth weight with cardiovascular disease risk factors including self-reported height, body mass index and hypertension than conventional regression in 2014.

RESULTS

Multiple birth (203 twins and 6 triplets) was associated with older maternal age, but not with paternal occupation or maternal smoking. Multiple births had lower birth weight-for-gestational age z-score. Multiple birth status was not directly associated with height, BMI or hypertension. Using IV estimates birth weight-for-gestational age z-score was not clearly associated with height (0.99cm, 95% confidence interval (CI) -0.27, 2.25), body mass index (BMI) (0.42kg/m(2), 95% CI -0.17, 1.01) or hypertension (risk ratio 0.82, 95% CI 0.54, 1.23) adjusted for maternal age, with a first-stage F statistic of 145.3 from IV analysis.

CONCLUSIONS

Multiple birth status is a credible IV for obtaining a less confounded estimate of the association of birth weight with height, BMI and blood pressure. Such analysis suggests that birth weight may be spuriously related to height, BMI and blood pressure, and thus not an effective target for intervention.

Routine Pediatric Enterovirus 71 Vaccination in China: a Cost-Effectiveness Analysis

BACKGROUND

China accounted for 87% (9.8 million/11.3 million) of all hand, foot, and mouth disease (HFMD) cases reported to WHO during 2010-2014. Enterovirus 71 (EV71) is responsible for most of the severe HFMD cases. Three EV71 vaccines recently demonstrated good efficacy in children aged 6-71 mo. Here we assessed the cost-effectiveness of routine pediatric EV71 vaccination in China.

METHODS AND FINDINGS

We characterized the economic and health burden of EV71-associated HFMD (EV71-HFMD) in China using (i) the national surveillance database, (ii) virological surveillance records from all provinces, and (iii) a caregiver survey on the household costs and health utility loss for 1,787 laboratory-confirmed pediatric cases. Using a static model parameterized with these data, we estimated the effective vaccine cost (EVC, defined as cost/efficacy or simply the cost of a 100% efficacious vaccine) below which routine pediatric vaccination would be considered cost-effective. We performed the base-case analysis from the societal perspective with a willingness-to-pay threshold of one times the gross domestic product per capita (GDPpc) and an annual discount rate of 3%. We performed uncertainty analysis by (i) accounting for the uncertainty in the risk of EV71-HFMD due to missing laboratory data in the national database, (ii) excluding productivity loss of parents and caregivers, (iii) increasing the willingness-to-pay threshold to three times GDPpc, (iv) increasing the discount rate to 6%, and (v) accounting for the proportion of EV71-HFMD cases not registered by national surveillance. In each of these scenarios, we performed probabilistic sensitivity analysis to account for parametric uncertainty in our estimates of the risk of EV71-HFMD and the expected costs and health utility loss due to EV71-HFMD. Routine pediatric EV71 vaccination would be cost-saving if the all-inclusive EVC is below US$10.6 (95% CI US$9.7-US$11.5) and would remain cost-effective if EVC is below US$17.9 (95% CI US$16.9-US$18.8) in the base case, but these ceilings could be up to 66% higher if all the test-negative cases with missing laboratory data are EV71-HFMD. The EVC ceiling is (i) 10%-14% lower if productivity loss of parents/caregivers is excluded, (ii) 58%-84% higher if the willingness-to-pay threshold is increased to three times GDPpc, (iii) 14%-19% lower if the discount rate is increased to 6%, and (iv) 36% (95% CI 23%-50%) higher if the proportion of EV71-HFMD registered by national surveillance is the same as that observed in the three EV71 vaccine phase III trials. The validity of our results relies on the following assumptions: (i) self-reported hospital charges are a good proxy for the opportunity cost of care, (ii) the cost and health utility loss estimates based on laboratory-confirmed EV71-HFMD cases are representative of all EV71-HFMD cases, and (iii) the long-term average risk of EV71-HFMD in the future is similar to that registered by national surveillance during 2010-2013.

CONCLUSIONS

Compared to no vaccination, routine pediatric EV71 vaccination would be very cost-effective in China if the cost of immunization (including all logistical, procurement, and administration costs needed to confer 5 y of vaccine protection) is below US$12.0-US$18.3, depending on the choice of vaccine among the three candidates. Given that the annual number of births in China has been around 16 million in recent years, the annual costs for routine pediatric EV71 vaccination at this cost range should not exceed US$192-US$293 million. Our results can be used to determine the optimal vaccine when the prices of the three vaccines are known.

Gestational Age, Birthweight for Gestational Age, and Childhood Hospitalisations for Asthma and Other Wheezing Disorders

BACKGROUND

Preterm birth, early term birth, and low birthweight are associated with childhood wheezing disorders in developed Western settings, but observed associations could be confounded by socio-economic position. This study aims to clarify such associations in a developed non-Western setting with a different confounding structure.

METHODS

Using Cox regression, we examined the adjusted associations of gestational age and birthweight for gestational age with time to first public hospital admission for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version Clinical Modification 466, 490, and 493) from 9 days to 12 years in a population-representative birth cohort of 8327 Chinese children in Hong Kong, a developed setting with less clear social patterning of prematurity or birthweight. Analyses were adjusted for infant and parental characteristics and socio-economic position.

RESULTS

Children born late preterm (34 to <37 weeks) had higher risk of hospitalisation for asthma and other wheezing disorders [hazard ratio (HR) 1.99, 95% confidence interval (CI) 1.48, 2.67] than children born full term (39 to <41 weeks). Early term births (37 to <39 weeks) had HR 1.01 (95% CI 0.84, 1.22), late term births (41 to <42 weeks) had HR 0.77 (95% 0.59, 1.01), and post-term births (≥42 weeks) had HR 0.56 (95% CI 0.32, 0.98). Large for gestational age was associated with lower risk of hospitalisation (HR 0.76, 95% CI 0.57, 0.99).

CONCLUSION

The association of preterm birth with childhood wheezing could be biologically mediated. We cannot rule out an association for early term births.

Mode of delivery and childhood hospitalizations for asthma and other wheezing disorders

BACKGROUND

Observationally, delivery by Caesarean section is associated with higher risk of childhood asthma and wheeze in developed Western settings, but associations are less consistent in other settings.

OBJECTIVE

To examine the association of mode of delivery with hospitalizations for asthma and other wheezing disorders in a developed non-Western setting with high rates of Caesarean section.

METHODS

Using Cox regression, we examined the adjusted association of mode of delivery with public hospital admissions for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version Clinical Modification 466, 490 and 493) from 9 days to 12 years of age in a population-representative prospective birth cohort of 8327 Chinese children in Hong Kong. Confounders included sex, birth and parental characteristics, and socio-economic position (SEP).

RESULTS

Delivery by Caesarean section accounted for 27% of all births and was not clearly associated with hospitalizations for asthma and other wheezing disorders to 12 years [hazard ratio (HR) 1.11, 95% confidence interval (CI) 0.91 to 1.36] compared to vaginal delivery. Similarly, there were no clear associations to 2 years (HR 1.07, 95% CI 0.83 to 1.38) or 6 years (HR 1.12, 95% CI 0.91 to 1.37), although we cannot rule out residual confounding by SEP.

CONCLUSIONS AND CLINICAL RELEVANCE

We cannot rule out an association, but our findings suggest that the observed associations of delivery by Caesarean section with childhood wheezing disorders may vary with setting and may not be biologically mediated. Further studies with different designs are needed to clarify the role of the microbiome and mode of delivery in the aetiology of asthma and other childhood wheezing disorders.

Interventions to reduce zoonotic and pandemic risks from avian influenza in Asia

Novel influenza viruses continue to emerge, posing zoonotic and potentially pandemic threats, such as with avian influenza A H7N9. Although closure of live poultry markets (LPMs) in mainland China stopped H7N9 outbreaks temporarily, closures are difficult to sustain, in view of poultry production and marketing systems in China. In this Personal View, we summarise interventions taken in mainland China, and provide evidence for other more sustainable but effective interventions in the live poultry market systems that reduce risk of zoonotic influenza including rest days, and banning live poultry in markets overnight. Separation of live ducks and geese from land-based (ie, non-aquatic) poultry in LPM systems can reduce the risk of emergence of zoonotic and epizootic viruses at source. In view of evidence that H7N9 is now endemic in over half of the provinces in mainland China and will continue to cause recurrent zoonotic disease in the winter months, such interventions should receive high priority in China and other Asian countries at risk of H7N9 through cross-border poultry movements. Such generic measures are likely to reduce known and future threats of zoonotic influenza.

Social Patterning in Adiposity in Adolescence: Prospective Observations from the Chinese Birth Cohort ''Children of 1997''

INTRODUCTION

Low early life socio-economic position is more strongly associated with adiposity among women than men. We examined whether the sex difference of social patterning in general and central adiposity exists before adulthood.

METHODS

In Hong Kong's "Children of 1997" birth cohort, we used multivariable regression to examine the association of parental education, a marker of early life socio-economic position, with body mass index (BMI) (n = 7252, 88% follow-up) and waist-height ratio (n = 5636, 68% follow-up), at 14 years.

RESULTS

Parental education of Grade 9 or below, compared to Grade 12 or above, was associated with higher waist-height ratio z-score particularly in girls (0.30, 95% confidence interval (CI) 0.19, 0.41) compared to boys (0.12, 95% CI 0.02, 0.22) (p for sex interaction = 0.02). Lower parental education was associated with greater BMI z-score in adolescents of locally born mothers, but not adolescents of migrant mothers, with no difference by sex.

CONCLUSIONS

Different social patterning in different markers of adiposity may imply different sociological and biological mediating pathways. A stronger association between low early life socio-economic position and waist-height ratio in adolescent girls may indicate sex-specific influences of SEP related early life exposures on central adiposity.

Normative data and psychometric properties of the Connor-Davidson Resilience Scale (CD-RISC) and the abbreviated version (CD-RISC2) among the general population in Hong Kong

PURPOSE

To examine whether the two-item version (CD-RISC2) of the Connor-Davidson Resilience Scale (CD-RISC) has adequate internal consistency and construct validity, as well as significant correlation with the full scale, and to provide normative data for the CD-RISC and the CD-RISC2 in a Chinese general population in Hong Kong.

METHODS

In total, 10,997 randomly selected participants aged ≥20 years completed the Chinese version of the CD-RISC (including the 2 items of the CD-RISC2), the Patient Health Questionnaire, Family Harmony Scale, Family APGAR, and CAGE Questionnaire. Internal consistency and convergent and discriminant validity of the CD-RISC and CD-RISC2 were assessed.

RESULTS

Cronbach's α for CD-RISC and CD-RISC2 was 0.97 and 0.79, respectively. CD-RISC2 was associated with the 25-item version of the CD-RISC (r = 0.88), depressive symptoms (r s = -0.18), family harmony (r = 0.20), family functioning (r = 0.27) and was not associated with alcohol consumption (r = 0.05). The mean score for the CD-RISC and CD-RISC2 was 59.99 (SD = 13.92) and 5.03 (SD = 1.37), respectively. Men, younger individuals, and those with higher education or higher household income reported higher resilience levels.

CONCLUSIONS

The Chinese version of the CD-RISC2 was demonstrated to be a reliable and valid measure in assessing resilience among the general population in Hong Kong.

Late prematurity and adiposity in adolescents: Evidence from "Children of 1997" birth cohort

OBJECTIVE

The association of late prematurity with later adiposity is unclear, and the mediating role of infant growth is seldom studied. We assessed the association of late prematurity with markers of adiposity in adolescence and tested whether accelerated infant weight gain mediated the association.

METHODS

In the Chinese birth cohort "Children of 1997," we used multivariable linear regression to assess the adjusted association of late premature (n = 295), compared to term (n = 6874), births with markers of adiposity at 14 years. We tested whether any association was mediated by accelerated weight gain from birth to 12 months, i.e., a change in weight z-score ≥0.67.

RESULTS

Late premature births had greater body mass index (BMI) z-score (0.21, 95% confidence interval (CI) 0.07, 0.35), waist-hip ratio z-score (0.16, 95% CI 0.03, 0.29), and waist-height ratio z-score (0.27, 95% CI 0.14, 0.40) than term births in adolescence. The association of late prematurity with higher adolescent BMI, but not waist ratios, was mediated by accelerated infant weight gain.

CONCLUSIONS

Late prematurity was associated with higher BMI and waist ratios in adolescence, but only the association with BMI was mediated by infant weight gain, suggesting vulnerability to metabolic risk in late premature births may arise through multiple pathways.

Early second-hand smoke exposure and child and adolescent mental health: evidence from Hong Kong's 'Children of 1997' birth cohort

BACKGROUND AND AIMS

Second-hand smoke (SHS) exposure is associated negatively with childhood behavioural problems in western settings. In a developed non-western setting, we estimated the associations of early SHS exposure during the prenatal and postnatal periods with several aspects of adolescent mental health.

DESIGN

Multivariable linear regression was used to estimate the adjusted associations of pre- and postnatal SHS exposure with adolescent mental health.

SETTING

Hong Kong.

PARTICIPANTS

Population-representative "Children of 1997" birth cohort. Behavioural problems at ~11 years were available for 5598, self-esteem at ~11 years for 6937 and depressive symptoms at ~13 years for 5797.

MEASUREMENTS

SHS was categorized as no SHS exposure, occasional prenatal SHS exposure from non-parental sources, daily prenatal SHS exposure from non-parental sources, postnatal SHS exposure from non-parental sources, prenatal and postnatal SHS exposure from non-parental sources, occasional paternal smoking, daily paternal smoking and any maternal smoking. Behavioural problems were assessed from parent-reported Rutter score, self-esteem from self-reported Culture-Free Self-Esteem Inventory score and depressive symptoms from self-reported Patient Health Questionnaire-9 score.

FINDINGS

Prenatal SHS exposure from non-parental sources was associated with behavioural problems at ~11 years (1.24, 95% confidence interval 0.20-2.28) adjusted for sex, age of assessment, survey mode (for depressive symptoms only), socio-economic position (SEP), mother's birthplace, gestational age and parity; paternal smoking and maternal smoking were associated with more mental health problems but also with lower SEP.

CONCLUSIONS

In Hong Kong, prenatal second-hand tobacco smoke exposure appears to be a risk factor for behavioural problems at age 11 years independent of socio-economic position.

The Dynamic Relationship Between Clinical Symptomatology and Viral Shedding in Naturally Acquired Seasonal and Pandemic Influenza Virus Infections

BACKGROUND

Although the pattern of viral shedding over time has been documented in volunteer challenge studies, understanding of the relationship between clinical symptomatology and viral shedding in naturally acquired influenza infections in humans remains limited.

METHODS

In a community-based study in Hong Kong from 2008 to 2014, we followed up initially healthy individuals and identified 224 secondary cases of natural influenza virus infection in the household setting. We examined the dynamic relationship between patterns of clinical symptomatology and viral shedding as quantified using reverse transcription polymerase chain reaction and viral culture in 127 cases with a clinical picture of acute respiratory infection.

RESULTS

Viral shedding in influenza A virus infections peaked on the first 1-2 days of clinical illness, and decreased gradually to undetectable levels by day 6-7, matching closely with the dynamics of clinical illness. Viral shedding in influenza B virus infections rose up to 2 days prior to symptom onset and persisted for 6-7 days after onset with a bimodal pattern.

CONCLUSIONS

Our results suggest that while clinical illness profiles may serve as a proxy for clinical infectiousness in influenza A virus infections, patients may potentially be infectious even before symptom onset or after clinical improvement in influenza B virus infections.

Breastfeeding and childhood hospitalizations for asthma and other wheezing disorders

PURPOSE

Observationally in Western settings, breastfeeding is associated with less childhood wheezing disorders but may be confounded by socioeconomic position. We examined the association of breastfeeding with asthma and other wheezing disorders in a developed non-Western setting with unique social patterning of breastfeeding.

METHODS

Using Cox regression, we examined the adjusted associations of breastfeeding with public hospital admissions for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version. Clinical Modification: 466, 490, and 493) from 3 months to 12 years in a population-representative birth cohort of 8327 Hong Kong Chinese children.

RESULTS

We did not find an association of exclusive breastfeeding for 3 months or more, compared with never breastfeeding, with hospitalization for asthma, bronchitis, and bronchiolitis to 12 years (hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.63-1.25) nor for partial breastfeeding for any length of time or exclusive breastfeeding for less than 3 months (HR, 1.02; 95% CI, 0.86-1.21), adjusted for infant and parental characteristics and socioeconomic position. We also did not find an association of exclusive breastfeeding for 3 months or more with hospitalization for asthma only (International Classification of Diseases, Ninth Version. Clinical Modification: 493) (HR, 1.27; 95% CI, 0.82-1.98).

CONCLUSIONS

In a large population-representative Chinese birth cohort, we did not find an association of breastfeeding with childhood hospitalizations for asthma and other wheezing disorders.

Comparative Epidemiology of Influenza B Yamagata- and Victoria-Lineage Viruses in Households

Influenza B viruses split into 2 distinct lineages in the early 1980s, commonly named the Victoria and Yamagata lineages. There are few data on the comparative epidemiology of Victoria- and Yamagata-lineage viruses. In 2007-2011, we enrolled 75 and 34 households containing index patients with acute respiratory illness who tested positive for Yamagata- and Victoria-lineage viruses, respectively, from outpatient clinics in Hong Kong, China. These index patients and their household contacts were followed up for 7-10 days. We examined overall risk of polymerase chain reaction-confirmed infection among household contacts and the risk of secondary infection within households using an individual-based hazard model that accounted for tertiary transmission and infections occurring outside the household. We found that for Victoria-lineage viruses, the risk of within-household infection among household contacts aged ≤15 years was significantly higher (risk ratio = 12.9, 95% credibility interval: 4.2, 43.6) than that for older household contacts, while for Yamagata-lineage viruses, the risk of within-household infection for household contacts did not differ by age. Influenza B Yamagata- and Victoria-lineage viruses have similar characteristics in terms of viral shedding and clinical illness. The mechanisms underlying these epidemiologic differences deserve further investigation.

Live Poultry Exposure and Public Response to Influenza A(H7N9) in Urban and Rural China during Two Epidemic Waves in 2013-2014

Background

The novel influenza A(H7N9) virus has caused 2013 spring and 2013–2014 winter waves of human infections since its first emergence in China in March 2013. Exposure to live poultry is a risk factor for H7N9 infection. Public psychobehavioral responses often change during progression of an epidemic.

Methods

We conducted population-based surveys in southern China to examine human exposure to live poultry, and population psychological response and behavioral changes in the two waves. In Guangzhou, an urban area of Guangdong province, we collected data using telephone surveys with random digit dialing in May-June 2013 and again in December 2013 to January 2014. In Zijin county, a rural area of the same province, we used door-to-door surveys under a stratified sampling design in July 2013 and again in December 2013 to January 2014. All responses were weighted by age and sex to the respective adult populations.

Findings

Around half of the urban respondents (53.8%) reported having visited LPMs in the previous year in the first survey, around double that reported in the second survey (27.7%). In the rural surveys, around half of the participants reported raising backyard poultry in the past year in the first survey, increasing to 83.2% participants in the second survey. One third of urban subjects supported the permanent closure of LPMs in the first and second surveys, and factors associated with support for closure included female sex, higher level of worry towards H7N9, and worry induced by a hypothetical influenza-like illness.

Conclusions

Our study indicated high human exposure to live poultry and low support for permanent closure of markets in both urban and rural residents regardless of increased worry during the epidemic.

Household income and adolescent blood pressure in a Chinese birth cohort: "Children of 1997"

The inconsistent relation of national income with population blood pressure raises questions as to whether social comparisons of relative income at individual or neighbourhood level may be more relevant than absolute income. We examined the associations of absolute household income (income per se), absolute neighbourhood median income (average income among geographically-proximate households), relative household income [deprivation using Yitzhaki index, or rank by position] (differences in income or rank compared with others) and relative neighbourhood income inequality [Gini coefficient] (income gap within a neighbourhood) with blood pressure z-score, prehypertension or hypertension at ∼13 years using a fixed effects multilevel linear or logistic model in a Chinese birth cohort (n = 5063, 61% of follow-up). Absolute household or neighbourhood income was not associated with adolescent blood pressure. Greater relative household income deprivation was associated with higher diastolic blood pressure (0.01 z-score per USD 128 difference in Yitzhaki index, 95% confidence interval (CI) 0.005 to 0.02), so was lower relative household income rank (-0.10, 95% CI -0.15 to -0.04), but relative neighbourhood income inequality was not, when considering each income measure separately. Such associations remained when considering all income measures together. Income measures were not associated with prehypertension or hypertension. Relative household income (greater deprivation or lower rank) were positively associated with adolescent blood pressure independent of absolute household income while absolute or relative neighbourhood income had little contribution, suggesting social comparisons at a key developmental stage could be relevant. Clarifying specific effects of socioeconomic position across the life-course could inform interventions.

Nut Consumption and Cardiovascular Risk in Older Chinese: The Guangzhou Biobank Cohort Study

Objectives

In Western contexts nut consumption is associated with better health. We examined the associations of nut consumption with cardiovascular disease risk in the non-Western setting of Southern China.

Methods

In the Guangzhou Biobank Cohort Study we used multivariable linear regression to examine the associations of baseline nut (mainly peanuts) consumption (none (n = 6688), <3 portions/week (n = 2596) and ≥3 portions/week (n = 2444)) with follow-up assessment of Framingham cardiovascular disease score (excluding smoking) and its components in older Chinese (≥50 years) (follow-up 57.8%).

Results

Nut consumption was not associated with Framingham score (≥3 portions/week compared to none: 0.02 95% confidence interval (CI) -0.11 to 0.15), systolic blood pressure (-0.66 mmHg 95% CI -1.94, 0.62), diastolic blood pressure (-0.69 mmHg 95% CI -1.44, 0.07), HDL-cholesterol (-0.01 mmol/L 95% CI -0.02, 0.005), LDL-cholesterol (-0.01 mmol/L 95% CI -0.05, 0.02) or fasting glucose (0.04 mmol/L 95% CI -0.02, 0.09), adjusted for baseline values, energy intake, age, sex, phase of recruitment, socio-economic position, lifestyle and baseline health status.

Conclusions

Observations concerning the benefits of nut consumption may be contextually specific, perhaps depending on the type of nut consumed.

Gestational age and adolescent mental health: evidence from Hong Kong's 'Children of 1997' birth cohort

BACKGROUND

Preterm, and more recently early term, birth has been identified as a risk factor for poor health. Whether the sequelae of late preterm or early term birth extends to poor mental health and well-being in adolescence is unclear and has not been systematically assessed.

METHOD

Linear regression was used to assess the adjusted associations of gestational age (very/moderate preterm (<34 weeks, n=85), late preterm (34-36 weeks, n=305), early term (37-38 weeks, n=2228), full term (39-40 weeks, n=4018), late term (41 weeks, n=809), post-term (≥42 weeks, n=213)) with self-reported self-esteem at ∼11 years (n=6935), parent-reported Rutter score assessing the common emotional and behavioural problems at ∼7 years (n=6292) and ∼11 years (n=5596) and self-reported depressive symptoms at ∼13 years (n=5795) in a population-representative Hong Kong Chinese birth cohort 'Children of 1997' where gestational age has little social patterning.

RESULTS

Very/moderate preterm birth was associated with higher Rutter subscore for hyperactivity (ß coefficients 0.5, 95% CI 0.01 to 1.00) at ∼7 years but not at ∼11 years, adjusted for sex, age, socio-economic position, parents' age at birth, birth order and secondhand smoke exposure. Similarly adjusted, late preterm, early term, late term and post-term birth were not associated with self-esteem or depressive symptoms.

CONCLUSIONS

In a population-representative birth cohort from a non-Western-developed setting, gestational age had few associations with mental health and well-being in adolescence, whereas very preterm birth was specifically associated with hyperactivity in childhood. Inconsistencies with studies from Western settings suggest setting specific unmeasured confounding may underlie any observed associations.

Fruit and vegetable consumption and cardiovascular risk factors in older Chinese: the Guangzhou biobank cohort study

Objective

To examine the adjusted associations of fruit consumption and vegetable consumption with the Framingham score and its components in the non-Western setting of Southern China, considering health status.

Method

Linear regression was used to assess the cross-sectional associations of fruit and vegetable consumption with the Framingham score and its components, among 19,518 older Chinese (≥50 years) from the Guangzhou Biobank Cohort Study in Southern China (2003–2006), and whether these differed by health status.

Results

The association of fruit consumption with the Framingham score varied by health status (P-value<0.001), but not vegetable consumption (P-value 0.51). Fruit consumption was associated with a lower Framingham score (-0.04 per portions/day, 95% confidence interval (CI) -0.08 to -0.004) among participants in poor health, adjusted for age, sex, recruitment phase, socio-economic position and lifestyle. However, similarly adjusted, fruit consumption was associated with a higher Framingham score (0.05, 95% CI 0.02 to 0.09) among participants in good health, perhaps due to a positive association of fruit consumption with fasting glucose. Similarly adjusted, vegetable consumption was associated with a higher Framingham score (0.03, 95% CI 0.01 to 0.05) among all participants, with no difference by health status.

Conclusion

This large study from a non-western setting found that fruit and vegetable consumption was barely associated with the Framingham score, or major CVD risk factors.

Association of Oseltamivir Treatment With Virus Shedding, Illness, and Household Transmission of Influenza Viruses

In an observational study of 582 patients with laboratory-confirmed influenza virus infections and their household contacts, we found that the initiation of oseltamivir within 24 hours was associated with shorter duration of self-reported illness symptoms (56% reduction in duration; 95% confidence interval, 41%-67%). However, we did not find any association of oseltamivir treatment with duration of viral shedding by polymerase chain reaction or with the risk of household transmission.

Towards informed decisions on breast cancer screening: Development and pilot testing of a decision aid for Chinese women

OBJECTIVE

To pilot-test a novel, self-use breast cancer (BC) screening decision aid (DA) targeting Hong Kong (HK) Chinese women at average risk of BC.

METHODS

Women were recruited through a population-based telephone survey using random digit dialling between October 2013 and January 2014. Eligible participants completed our baseline survey and then received the DA by post. Participants (n=90) completed follow-up telephone interviews one month later.

RESULTS

Most participants thought that all/most DA content was presented clearly (86.7%), and was useful in helping women make screening-related decisions (88.9%). It also achieved its expected impact of improving informed decision-making and increasing shared-participation preference without increasing participants' anxiety levels. Participants showed a modest non-statistical increase in their screening knowledge scores. Older women rated the perceived severity of a BC diagnosis as significantly lower, and more educated women reported significantly lower perceived anxiety about the disease.

CONCLUSION

Our DA appears acceptable and feasible for self-use by HK Chinese women who need to make an informed decision about BC screening without increasing overall anxiety levels.

PRACTICE IMPLICATIONS

This study supports the potential of self-use DAs for cancer screening-related decision support in a Chinese population.

Structure and validity of Family Harmony Scale: An instrument for measuring harmony

Culture plays a role in mental health, partly by defining the characteristics that are indicative of positive adjustment. In Chinese cultures, positive family relationships are considered central to well-being. The culturally emphasized characteristic of family harmony may be an important factor associated with psychopathology. This article presents the development and psychometric examination of the Family Harmony Scale (FHS), an indigenously developed 24-item instrument tapping family harmony in 17,461 Hong Kong residents from 7,791 households. A higher-order model with 1 second-order factor and 5 first-order factors fit the data well and showed factorial invariance across sex and participants in different family roles. A 5-item short form (FHS-5) was also developed, with 1 item from each first-order factor. The short scale showed, as expected, a single-factor structure with good fit. Both scales demonstrated high internal consistency, acceptable test-retest reliability, and good convergent and discriminant validity. The 24-item FHS was negatively associated with depressive symptoms after accounting for individual risk factors and general family function. Family harmony moderated the relationship between life stress and depressive symptoms such that those individuals who reported low family harmony had stronger associations between life stress and depressive symptoms. This study adds to the literature a systematically developed, multidimensional measure of family harmony, which may be an important psychological protective factor, in a large urban Chinese sample. The FHS-5 minimizes operational and respondent burdens, making it an attractive tool for large-scale epidemiological studies with Chinese populations in urban settings, where over half of China's 1.4 billion people reside.

The Association of Infant Growth Patterns with Adiposity in Adolescence: Prospective Observations from Hong Kong's 'Children of 1997' Birth Cohort

BACKGROUND

The role of infant growth in adiposity remains unclear.

METHODS

We used multivariable linear regression, with inverse probability weighting and multiple imputation to account for loss to follow-up, in a population-representative Chinese birth cohort, 'Children of 1997' in Hong Kong, to examine, in terms births, the adjusted association of infant (birth to 12 months) weight growth trajectories with body mass index (BMI) (n = 6861, 88% follow-up), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR) (n = 5398, 69% follow-up) at ∼ 14 years.

RESULTS

Infant weight growth trajectories had graded associations with adolescent BMI and WHtR but not with WHR, such that compared with adolescents born light with slow infant growth, adolescents born heavy with fast infant growth had higher BMI z-score [0.60, 95% confidence interval (CI) 0.49, 0.70], higher WHtR z-score (0.17, 95% CI 0.08, 0.26) but similar WHR z-score (-0.02, 95% CI -0.11, 0.08), adjusted for sex, gestational age, parental education, parental BMI, parental height, and parental place of birth.

CONCLUSIONS

Varying associations of infant growth with different adiposity measures suggest a complex role of infant growth in long-term health, perhaps because infant growth, or its underlying drivers, influences build and body composition as well as adiposity.

Preliminary epidemiological assessment of MERS-CoV outbreak in South Korea, May to June 2015

South Korea is experiencing the largest outbreak of Middle East respiratory syndrome coronavirus infections outside the Arabian Peninsula, with 166 laboratory-confirmed cases, including 24 deaths up to 19 June 2015. We estimated that the mean incubation period was 6.7 days and the mean serial interval 12.6 days. We found it unlikely that infectiousness precedes symptom onset. Based on currently available data, we predict an overall case fatality risk of 21% (95% credible interval: 14–31).

Preliminary epidemiological assessment of MERS-CoV outbreak in South Korea, May to June 2015

South Korea is experiencing the largest outbreak of Middle East respiratory syndrome coronavirus infections outside the Arabian Peninsula, with 166 laboratory-confirmed cases, including 24 deaths up to 19 June 2015. We estimated that the mean incubation period was 6.7 days and the mean serial interval 12.6 days. We found it unlikely that infectiousness precedes symptom onset. Based on currently available data, we predict an overall case fatality risk of 21% (95% credible interval: 14–31).

Poultry market closures and human infection with influenza A(H7N9) virus, China, 2013-14

Closure of live poultry markets was implemented in areas affected by the influenza virus A(H7N9) outbreak in China during winter, 2013–14. Our analysis showed that closing live poultry markets in the most affected cities of Guangdong and Zhejiang provinces was highly effective in reducing the risk for H7N9 infection in humans.

Dissemination, divergence and establishment of H7N9 influenza viruses in China

Since 2013 the occurrence of human infections by a novel avian H7N9 influenza virus in China has demonstrated the continuing threat posed by zoonotic pathogens. Although the first outbreak wave that was centred on eastern China was seemingly averted, human infections recurred in October 2013 (refs 3-7). It is unclear how the H7N9 virus re-emerged and how it will develop further; potentially it may become a long-term threat to public health. Here we show that H7N9 viruses have spread from eastern to southern China and become persistent in chickens, which has led to the establishment of multiple regionally distinct lineages with different reassortant genotypes. Repeated introductions of viruses from Zhejiang to other provinces and the presence of H7N9 viruses at live poultry markets have fuelled the recurrence of human infections. This rapid expansion of the geographical distribution and genetic diversity of the H7N9 viruses poses a direct challenge to current disease control systems. Our results also suggest that H7N9 viruses have become enzootic in China and may spread beyond the region, following the pattern previously observed with H5N1 and H9N2 influenza viruses.

Adiposity and early adolescent emotional/behavioral problems

OBJECTIVE

To examine whether life course adiposity is associated with emotional/behavioral problems in a non-Western developed setting with little social patterning of adiposity.

STUDY DESIGN

In a prospective, population-representative Chinese birth cohort, "Children of 1997," multivariable partial least squares regression was used to assess the adjusted associations of birth weight z-score, body mass index (BMI) z-scores at ages 3 months, 9 months, 3 years, 7 years, 9 years, and BMI z-score changes with emotional/behavioral problems at ∼ 11 years of age, assessed from the Chinese version of the Revised Parent's Rutter Scales.

RESULTS

Rutter score was available for 4976 (62.8% follow-up). Birth weight z-score, BMI z-scores at ages 3 months, 9 months, 3 years, 7 years, 9 years, and successive BMI z-scores changes had little association with Rutter score or subscores at ∼ 11 years of age, adjusted for socioeconomic position, although birth weight was negatively associated with specifically hyperactivity.

CONCLUSIONS

In a developed, non-Western setting, we did not find adiposity be a factor in the development of emotional/behavioral problems in early adolescence. Although, we cannot rule out the possibility of residual confounding by genetic or familial factors, our results suggest that the reported associations may be contextually specific rather than biologically based. Whether lower birth weight is associated with hyperactivity in early adolescence needs to be confirmed or refuted in other suitable settings.

Burden, seasonal pattern and symptomatology of acute respiratory illnesses with different viral aetiologies in children presenting at outpatient clinics in Hong Kong

Respiratory viruses cause acute respiratory diseases with a broad and overlapping spectrum of symptoms. We examined the clinical symptoms and explored the patterns of various respiratory viral infections in children in Hong Kong. Among 2090 specimens collected from outpatient care (2007–2010), 1343 (64.3%) were positive for any virus by the xTAG assay, and 81 (3.9%) were positive for co-infection. The most frequently detected viruses among children aged 6–15 years were enterovirus/rhinovirus and influenza virus A, whereas most non-influenza viruses were more frequently detected in younger children. Higher body temperature was more common for illnesses associated with influenza viruses than for those associated with non-influenza viruses, but other symptoms were largely similar across all infections. The seasonality pattern varied among different viruses, with influenza virus A being the predominant virus detected in winter, and enterovirus/rhinovirus being more commonly detected than influenza virus A in the other three seasons, except for 2009.

Genetically predicted testosterone and systemic inflammation in men: a separate-sample Mendelian randomization analysis in older Chinese men

Objectives

Observationally, testosterone is negatively associated with systemic inflammation, but this association is open to both residual confounding and reverse causality. Large-scale randomized controlled trials (RCTs), assessing exogenous effects, are presently unavailable. We examined the association of endogenous testosterone with well-established systemic inflammatory markers (white blood cell, granulocyte, lymphocyte and high-sensitivity C-reactive protein (hsCRP)) using a separate-sample Mendelian randomization analysis to minimize reverse causality.

Methods

A genetic prediction rule for serum testosterone was developed in 289 young Chinese men with mean age of 21.0, using selected testosterone-related SNPs (rs10046, rs1008805 and rs1256031). Multivariable linear regression was used to examine the association of genetically predicted serum testosterone with inflammatory markers among 4,212 older Chinese men from the Guangzhou Biobank Cohort Study.

Results

Genetically predicted testosterone was unrelated to white blood cell count (-0.01 109/L per nmol/L testosterone, 95% confidence interval (CI) -0.05 to 0.04), granulocyte count (-0.02 109/L, 95% CI -0.06 to 0.02), lymphocyte count (0.005 109/L, 95% CI -0.01 to 0.02) and hsCRP (-0.05 mg/L, 95% CI -0.15 to 0.06).

Conclusion

Our findings did not corroborate any anti-inflammatory effects of testosterone or corresponding potentially protective effects of testosterone on chronic diseases resulting from reduced low-grade systemic inflammation.

Differences in the Epidemiology of Human Cases of Avian Influenza A(H7N9) and A(H5N1) Viruses Infection

BACKGROUND

The pandemic potential of avian influenza viruses A(H5N1) and A(H7N9) remains an unresolved but critically important question.

METHODS

We compared the characteristics of sporadic and clustered cases of human H5N1 and H7N9 infection, estimated the relative risk of infection in blood-related contacts, and the reproduction number (R).

RESULTS

We assembled and analyzed data on 720 H5N1 cases and 460 H7N9 cases up to 2 November 2014. The severity and average age of sporadic/index cases of H7N9 was greater than secondary cases (71% requiring intensive care unit admission vs 33%, P = .007; median age 59 years vs 31, P < .001). We observed no significant differences in the age and severity between sporadic/index and secondary H5N1 cases. The upper limit of the 95% confidence interval (CI) for R was 0.12 for H5N1 and 0.27 for H7N9. A higher proportion of H5N1 infections occurred in clusters (20%) compared to H7N9 (8%). The relative risk of infection in blood-related contacts of cases compared to unrelated contacts was 8.96 for H5N1 (95% CI, 1.30, 61.86) and 0.80 for H7N9 (95% CI, .32, 1.97).

CONCLUSIONS

The results are consistent with an ascertainment bias towards severe and older cases for sporadic H7N9 but not for H5N1. The lack of evidence for ascertainment bias in sporadic H5N1 cases, the more pronounced clustering of cases, and the higher risk of infection in blood-related contacts, support the hypothesis that susceptibility to H5N1 may be limited and familial. This analysis suggests the potential pandemic risk may be greater for H7N9 than H5N1.

Influenza A Virus Shedding and Infectivity in Households

BACKGROUND

Viral shedding is often considered to correlate with the infectivity of influenza, but the evidence for this is limited.

METHODS

In a detailed study of influenza virus transmission within households in 2008-2012, index case patients with confirmed influenza were identified in outpatient clinics, and we collected nose and throat swab specimens for testing by reverse-transcription polymerase chain reaction from all household members regardless of illness. We used individual-based hazard models to characterize the relationship between viral load (V) and infectivity.

RESULTS

Assuming that infectivity was proportional to viral load V gave the worst fit, because it strongly overestimated the proportion of transmission occurring at symptom onset. Alternative models assuming that infectivity was proportional to a various functions of V provided better fits, although they all overestimated the proportion of transmission occurring >3 days after symptom onset. The best fitting model assumed that infectivity was proportion to V(γ), with estimates of γ = 0.136 and γ = 0.156 for seasonal influenza A(H1N1) and A(H3N2) respectively.

CONCLUSIONS

All the models we considered that used viral loads to approximate infectivity of a case imperfectly explained the timing of influenza secondary infections in households. Identification of more accurate correlates of infectivity will be important to inform control policies and disease modeling.

Adolescent testosterone, muscle mass and glucose metabolism: evidence from the 'Children of 1997' birth cohort in Hong Kong

AIMS

Diabetes rates are high in Asia despite relatively low rates of obesity, which might be related to lower muscle mass. Muscle mass plays an important role in glucose metabolism. Peak muscle mass is obtained in late adolescence. We tested the hypothesis that pubertal testosterone is negatively associated with glucose metabolism mediated by muscle mass.

METHODS

Participants aged 15 years (278 boys and 223 girls) were recruited from the Hong Kong's 'Children of 1997' birth cohort in 2012. Multivariable linear regression with multiple imputation and inverse probability weighting was used to examine the adjusted associations of pubertal testosterone with skeletal muscle index, body fat percentage, fasting glucose, insulin and homeostasis model of assessment - insulin resistance.

RESULTS

Total testosterone was negatively associated with fasting glucose (-0.008, 95% confidence interval -0.015 to -0.002), insulin (-0.43, 95% confidence interval -0.56 to -0.30) and insulin and homeostasis model of assessment - insulin resistance (-0.09, 95% confidence interval -0.12 to -0.06) adjusted for sex, birth weight, highest parental education, mother's place of birth and physical activity. These associations were attenuated by additional adjustment for skeletal mass index or body fat percentage.

CONCLUSIONS

Adolescent glucose metabolism may be influenced by testosterone, perhaps partially via skeletal muscle mass.

Informal child care and adolescent psychological well-being: Hong Kong's "Children of 1997" birth cohort

BACKGROUND

Informal child care (child care by untrained family members, relatives or employees in the home) in Western populations is often associated with poorer psychological well-being, which may be confounded by socioeconomic position. We examined the association of informal child care, common in non-Western settings, with adolescent psychological well-being, using Hong Kong's Chinese "Children of 1997" birth cohort.

METHODS

Multivariable linear regression was used to examine the adjusted associations of informal child care (at 0.5, 3, 5 and 11 years) with parent-reported Rutter score for child behavior at 11 years, self-reported Culture-Free Self-Esteem Inventories score at 11 years and self-reported Patient Health Questionnaire-9 depressive symptom score at 13 years. Model comparisons were used to identify the best representation of child care, in terms of a critical period of exposure to informal child care (independent variable) at a specific age, combination of exposures to informal child care at several ages or an accumulation of exposures to informal child care.

RESULTS

Child care was not associated with behavioral problems. A model considering child care at 3 years best represented the association of child care with self-esteem while a model considering child care at 5 years best represented the association of child care with depressive symptoms. Informal child care at 3 years was associated with lower self-esteem (-0.70, 95% confidence interval (CI) -1.26 to -0.14). Informal child care at 5 years was associated with more depressive symptoms (0.45, 95% CI 0.17 to 0.73).

CONCLUSION

In a developed non-Western setting, informal child care was associated with lower self-esteem and more depressive symptoms.

Smoking and mortality in a prospective cohort study of elderly Chinese in Hong Kong

BACKGROUND AND AIMS

Large cohort studies on smoking and mortality in elderly people are scarce, and few studies examined smokers aged 85+ years separately. We estimated the risks of all-cause and cause-specific mortality due to smoking in an elderly Chinese cohort in Hong Kong.

DESIGN

A population-based prospective cohort of 65,510 Chinese enrolled from 1998 to 2001 and followed until May 2012.

SETTING

All 18 Elderly Health Service centres in Hong Kong, China.

PARTICIPANTS

Elderly people aged 65+ years.

MEASUREMENTS

Self-reported smoking status was assessed at baseline interview and categorized as never, former and current smokers.

FINDINGS

Compared with never smokers, after adjustment for sex, age, education, social security assistance, housing type, monthly expenditure, alcohol use, depressive symptoms and health status, the hazard ratio (HR) for current smokers was 1.89 [95% confidence interval (CI) = 1.81-1.98] for all participants aged 65+ years at baseline, corresponding to an attributable fraction (AF) of about 50%, which is based on AF = (HR-1)/HR. As the effect of smoking varied with age (P for age interaction <0.001), subgroup analysis by age group showed that the adjusted HR for current smokers aged 65-84 years was 1.93 (95% CI = 1.84-2.03), and for 85+ years was 1.29 (95% CI = 1.05-1.58). All the risk estimates did not vary by sex (P for sex interaction ranged 0.74-0.89).

CONCLUSIONS

In Hong Kong, the risk of death from smoking appears to be the same for Chinese women as it is for men. Half of all deaths in Chinese smokers aged 65 years and older and a quarter of all deaths in Chinese smokers aged 85 years and older are caused by smoking-attributable diseases.

Public risk perception and attitudes towards live poultry markets before and after their closure due to influenza A(H7N9), Hong Kong, January-February 2014

BACKGROUND

The study investigated public risk perception regarding influenza A(H7N9) and attitudes towards closure of live poultry markets (LPMs) before and after LPMs closed in Hong Kong.

METHODS

Two population-based surveys were conducted before and after LPMs closed in January-February 2014, respectively. Adults were recruited using random digital dialing.

RESULTS

In total, 670 and 1011 respondents completed the survey before and after closure of LPMs, respectively. Perceived susceptibility to H7N9 infection was low across surveys. Among respondents who completed the survey after LPMs closed, only 14.6% agreed that temporary closure of LPMs caused inconvenience to the daily life; 38.7% valued the Chinese tradition of live poultry consumption more than controlling the risk of avian influenza; 54.6% recognized greater risk of influenza epidemic associated with LPMs. Support for permanent closure of LPMs which was comparably low across surveys was strongly associated with perceived risk of avian influenza related to LPMs, the effectiveness of LPM closure in control of avian influenza and the inconvenience caused by closure.

CONCLUSIONS

Risk communication that promotes people's perceived risk of avian influenza associated with LPMs and the effectiveness of LPM closure in control of avian influenza outbreaks may improve support for permanent closure of LPMs.

Life course body mass index and adolescent self-esteem: Evidence from Hong Kong's "Children of 1997" Birth Cohort

OBJECTIVE

Self-esteem is an important determinant of adolescent mental health. Prior adiposity may be a factor in the development of self-esteem. However, the association of adiposity with self-esteem is inconsistent, perhaps because adiposity and self-esteem tend to be socially patterned, making it unclear whether observed associations are biologically based or contextually specific.

METHODS

Multivariable partial least squares regression was used to assess the adjusted association of birth weight and childhood body mass index (BMI) z-score at 3 and 9 months and at 3, 7, 9 and 11 years and changes in BMI z-score with self-esteem at ∼11 years, assessed from the self-reported Culture Free Self-Esteem Inventory in a population-representative Chinese birth cohort, which has little social patterning of adiposity. Whether the associations varied by sex also was assessed.

RESULTS

Self-esteem score was available for 6,520 girls and boys (78.5% follow-up). Birth weight z-score, BMI z-scores at 3 and 9 months and at 3, 7, 9, and 11 years, and successive BMI z-score changes had little association with self-esteem at ∼11 years, adjusted for socio-economic position.

CONCLUSIONS

In a developed, non-Western setting, life course BMI does not appear to be a factor in the development of self-esteem in early adolescence, suggesting that observed associations to date may be contextually specific rather than biologically based.

Transmissibility of the Ice Bucket Challenge among globally influential celebrities: retrospective cohort study

OBJECTIVES

To estimate the transmissibility of the Ice Bucket Challenge among globally influential celebrities and to identify associated risk factors.

DESIGN

Retrospective cohort study.

SETTING

Social media (YouTube, Facebook, Twitter, Instagram).

PARTICIPANTS

David Beckham, Cristiano Ronaldo, Benedict Cumberbatch, Stephen Hawking, Mark Zuckerberg, Oprah Winfrey, Homer Simpson, and Kermit the Frog were defined as index cases. We included contacts up to the fifth generation seeded from each index case and enrolled a total of 99 participants into the cohort.

MAIN OUTCOME MEASURES

Basic reproduction number R0, serial interval of accepting the challenge, and odds ratios of associated risk factors based on fully observed nomination chains; R0 is a measure of transmissibility and is defined as the number of secondary cases generated by a single index in a fully susceptible population. Serial interval is the duration between onset of a primary case and onset of its secondary cases.

RESULTS

Based on the empirical data and assuming a branching process we estimated a mean R0 of 1.43 (95% confidence interval 1.23 to 1.65) and a mean serial interval for accepting the challenge of 2.1 days (median 1 day). Higher log (base 10) net worth of the participants was positively associated with transmission (odds ratio 1.63, 95% confidence interval 1.06 to 2.50), adjusting for age and sex.

CONCLUSIONS

The Ice Bucket Challenge was moderately transmissible among a group of globally influential celebrities, in the range of the pandemic A/H1N1 2009 influenza. The challenge was more likely to be spread by richer celebrities, perhaps in part reflecting greater social influence.

Clinical severity of human infections with avian influenza A(H7N9) virus, China, 2013/14

Assessing the severity of emerging infections is challenging because of potential biases in case ascertainment. The first human case of infection with influenza A(H7N9) virus was identified in China in March 2013; since then, the virus has caused two epidemic waves in the country. There were 134 laboratory-confirmed cases detected in the first epidemic wave from January to September 2013. In the second epidemic wave of human infections with avian influenza A(H7N9) virus in China from October 2013 to October 2014, we estimated that the risk of death among hospitalised cases of infection with influenza A(H7N9) virus was 48% (95% credibility interval: 42-54%), slightly higher than the corresponding risk in the first wave. Age-specific risks of death among hospitalised cases were also significantly higher in the second wave. Using data on symptomatic cases identified through national sentinel influenza-like illness surveillance, we estimated that the risk of death among symptomatic cases of infection with influenza A(H7N9) virus was 0.10% (95% credibility interval: 0.029-3.6%), which was similar to previous estimates for the first epidemic wave of human infections with influenza A(H7N9) virus in 2013. An increase in the risk of death among hospitalised cases in the second wave could be real because of changes in the virus, because of seasonal changes in host susceptibility to severe infection, or because of variation in treatment practices between hospitals, while the increase could be artefactual because of changes in ascertainment of cases in different areas at different times.

Responses to threat of influenza A(H7N9) and support for live poultry markets, Hong Kong, 2013

We conducted a population survey in Hong Kong to gauge psychological and behavioral responses to the threat of influenza A(H7N9) and support for closure of live poultry markets. We found low anxiety and low levels of exposure to live poultry but mixed support for permanent closure of the markets.

Cohort Profile: Hong Kong Department of Health Elderly Health Service Cohort

The Department of Health Elderly Health Service Cohort in Hong Kong was set up to promote understanding of ageing in a global context, to exploit the role of Hong Kong as a sentinel for populations currently experiencing very rapid economic development, to provide a developed non-Western 'social laboratory' where empirically derived hypotheses can be tested and to leverage the different patterns of common chronic diseases between East and West to generate novel hypotheses about their determinants. The initial cohort enrolled from July 1998 to the end of December 2001 includes 66 820 people aged 65 years or older, forming about 9% of the population of this age. A comprehensive health assessment was made at enrollment and then repeated regularly on an ongoing basis. The health assessment included a comprehensive assessment of lifestyle, social circumstances, physical health and mental health, including an assessment of cognition and depressive symptoms. Health services use and deaths have been obtained by record linkage and confirmed, where necessary, by telephone interview. Currently, the data are not publicly available; we would welcome collaborations and research proposals.

A new birthweight reference in Guangzhou, southern China, and its comparison with the global reference

OBJECTIVE

To formulate a new birthweight reference for different gestational ages in Guangzhou, southern China, and compare it with the currently used reference in China and the global reference.

DESIGN AND SETTING

All singleton live births of more than 26 weeks' gestational age recorded in the Guangzhou Perinatal Health Care and Delivery Surveillance System for the years 2009, 2010 and 2011 (n=510 837) were retrospectively included in the study. In addition, the study sample was supplemented by all singleton live births (n=3538) at gestational ages 26-33 weeks from 2007 and 2008. We used Gaussian mixture models and robust regression to exclude outliers of birth weight and then applied Generalized Additive Models for Location, Scale, and Shape (GAMLSS) to generate smoothed percentile curves separately for gender and parity.

RESULTS

Of infants defined as small for gestational age (SGA) in the new reference, 15.3-47.7% (depending on gestational age) were considered appropriate for gestational age (AGA) by the currently used reference of China. Of the infants defined as SGA by the new reference, 9.2% with gestational ages 34-36 weeks and 14.3% with 37-41 weeks were considered AGA by the global reference. At the 50th centile line, the new reference curve was similar to that of the global reference for gestational ages 26-33 weeks and above the global reference for 34-40 weeks.

CONCLUSIONS

The new birthweight reference based on birthweight data for neonates in Guangzhou, China, differs from the reference currently used in China and the global reference, and appears to be more relevant to the local population.

Psychometric evaluation of the Chinese version of the Subjective Happiness Scale: evidence from the Hong Kong FAMILY Cohort

Background

With China’s rapid economic growth in the past few decades, there is currently an emerging focus on happiness. Cross-cultural validity studies have indicated that the four-item Subjective Happiness Scale (SHS) has high internal consistency and stable reliability. However, the psychometric characteristics of the SHS in broader Chinese community samples are unknown.

Purpose

We evaluated the factor structure and psychometric properties of the SHS in the Hong Kong general population.

Methods

The Chinese SHS was derived using forward–backward translation. Of the Cantonese-speaking participants aged ≥15 years, 2,635 were randomly selected from the random sample component of the FAMILY Cohort, a territory-wide cohort study in Hong Kong. In addition to the SHS, a single-item overall happiness scale, the Patient Health Questionnaire-9 (PHQ-9), the Family Adaptation, Partnership, Growth, Affection, Resolve (APGAR) scale, and the Medical Outcomes Study 12-item short-form version 2 (SF-12) mental and physical health scales were administered.

Results

Exploratory and confirmatory factor analyses supported a single factor with high loadings for the four SHS items. Multiple group analyses indicated factor invariance across sex and age groups. Cronbach’s alpha was 0.82, and 2-week test–retest reliability (n = 191) was 0.70. The SHS correlated significantly with single-item overall happiness (Spearman’s rho [ρ] = 0.57), Family APGAR (ρ = 0.26), PHQ-9 (ρ = −0.34), and mental health-related quality of life (ρ = 0.40) but showed a lower correlation with physical health (ρ = 0.15). A regression model that included the PHQ-9 and Family APGAR scores explained 37 % of the variance in SF-12 mental health scores; adding the SHS raised the variance explained to 41 %.

Conclusions

Our results support the reliability and validity of the SHS as a relevant component in the measurement battery for mental well-being in a Chinese general population.

Migrant status and child and adolescent psychological well-being: evidence from Hong Kong's 'Children of 1997' birth cohort

BACKGROUND

In Western settings, migration is associated with psychological well-being, but studies inevitably focus on culturally distinct ethnic minorities, making it difficult to distinguish migration from cultural assimilation. Many children in Hong Kong, a developed non-Western setting, have migrant parents with the same Chinese ethnicity. This study examined the association of migration with the child's psychological well-being in Hong Kong.

METHODS

Multivariable linear regression was used in Hong Kong's 'Children of 1997' Chinese birth cohort to examine the adjusted associations of migration (both parents Hong Kong born n=4285, both parents migrant n=1921, mother-only migrant n=462, father-only migrant n=1110) with a parent-reported Rutter score for child behaviour at ∼7 (n=6294, 80% follow-up) and ∼11 years (n=5598, 71% follow-up), self-reported Culture-Free Self-Esteem Inventory score at ∼11 years (n=6937, 88% follow-up) and self-reported Patient Health Questionnaire-9 (PHQ-9) depressive symptom score at ∼13 years (n=5797, 73% follow-up), adjusted for sex, highest parental education and occupation, household income, maternal and paternal age at birth, age of assessment and survey mode (PHQ-9 only).

RESULTS

Migration was unrelated to the overall self-esteem or depressive symptoms, but both parents migrant was associated with better behaviour (lower Rutter scores) at ∼7 years (β-coefficient (β) -1.07, 95% CI -1.48 to -0.66) and ∼11 years (-0.89, 95% CI -1.33 to -0.45).

CONCLUSIONS

In a non-Western context, migration appeared to be protective for childhood behaviour.