Wing-Sze Lo

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.

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.

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.

Smoking and sleep disorders in Chinese adolescents

OBJECTIVE To investigate the association between adolescent smoking and sleep disorders. METHODS In the Hong Kong student obesity surveillance project, 29,397 Chinese students, aged 12-18 years, completed a health survey. Insomnia was defined as having any of the following three symptoms: difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS) and early morning awakening (EMA). The presence of snoring and difficulty breathing during sleep (DBS) was also reported. Logistic regression yielded adjusted odds ratios (ORs) for each sleep disorder by smoking status. RESULTS Compared with never smokers, the ORs (95% CI) of insomnia were 1.39 (1.25-1.54) for experimenters (smoked once or a few times) and 0.91 (0.83-1.00) for current smokers. The corresponding ORs were 1.42 (1.16-1.74) and 3.58 (3.15-4.06) for snoring (P for trend<0.001) and 1.40 (1.10-1.79) and 3.39 (2.97-4.03) for DBS (P for trend<0.001). Current smokers compared with never smokers were less likely to report DIS (OR=0.43, 95% CI=0.38-0.50, P<0.001) and EMA (OR=0.83, 95% CI=0.73-0.94, P=0.003), but more likely to report DMS (OR=1.45, 95% CI=1.28-1.63, P<0.001). CONCLUSIONS In terms of dosage, adolescent smoking was associated with snoring and DBS, with increasing ORs from never smokers to experimental and current smokers. Current smoking was associated positively with DMS, but negatively with DIS and EMA.

Neighbourhood food environment and dietary intakes in adolescents: sex and perceived family affluence as moderators.

OBJECTIVE To examine the effects of perceived availability of fast-food shops, restaurants, and convenience stores on adolescent dietary intakes. METHODS Survey data from 34 369 students in 42 Hong Kong secondary schools were collected in 2006-7. Respondents reported the availability of fast-food shops, restaurants and convenience stores in the neighbourhood, and their intakes of fruit, vegetables, high-fat foods and junk food/soft drinks. For intakes of high-fat foods and junk food/ soft drinks, ≤ once a week was defined as low consumption and the rest moderate/high consumption. At least three servings of vegetables and two servings of fruit daily were defined as sufficient consumption. Logistic regression yielded adjusted odds ratios (OR) for each dietary intake in relation to the reported food shops. Potential effect modifications by socio-demographic factors were also examined. RESULTS Perceived availability of fast-food shops and convenience stores were positively associated with moderate/high consumptions of high-fat foods (OR(fast) =1.10 and OR(con) =1.15) and junk food/soft drinks (OR(fast)=1.10 and OR(con) =1.10). Significant negative associations of the perceived availability of restaurants with intakes of vegetables and fruit were observed (OR(veg) =0.87 and OR(fruit) =0.83). The positive relationship between reporting fast-food shops with intake of junk food/soft drinks were observed only in boys and those with low perceived family affluence. The negative association of reporting restaurants with fruit consumption was found in those with low and middle perceived family affluence only. CONCLUSIONS Perceived availability of neighbourhood fast-food shops, restaurants, and convenience stores may have a negative impact on adolescent dietary intakes particularly for those from poorer families.

Smoking is associated with poor self-rated health among adolescents in Hong Kong.

INTRODUCTION To investigate the association between smoking and self-rated health (SRH) among adolescents in Hong Kong. METHODS Form 1 (U.S. Grade 7) to 5 students (N = 36,225) from 85 randomly selected secondary schools were surveyed using anonymous, self-administered questionnaires to collect information about smoking, SRH, secondhand smoke exposure, drinking, illicit drug use, physical activities, medical services use, health complaints, and sociodemographic characteristics. Logistic regression yielded adjusted odds ratios (AORs) for poor SRH due to smoking in boys and girls. RESULTS Compared with never-smoking, smoking experimentation, ex-smoking, and current smoking were associated with AORs (95% CI) for poor SRH of 1.22 (1.07-1.40), 1.43 (1.12-1.83), and 1.31 (1.13-1.53), p for trend <.001, in boys and 1.26 (1.10-1.39), 1.42 (1.08-1.85), and 1.75 (1.53-2.00, p for trend <.001, in girls. The AOR of poor SRH for current smoking was higher in girls than boys, p for interaction <.001. Current and experimental smoking but not ex-smoking were significantly associated with poor SRH among healthy students who had no health complaints or recent medical consultations. Increasing cigarette consumption, years of smoking, and smoking urge were also significantly associated with poor SRH. CONCLUSIONS Smoking was associated with poor SRH among Chinese adolescents, especially girls. This finding is useful for discouraging smoking initiation and motivating quitting in adolescent smokers.

Prospective effects of weight perception and weight comments on psychological health among Chinese adolescents

Aim:  To investigate the prospective effects of weight perception of self and weight comments by others on psychological health problems among Chinese adolescents.

Smoking family, secondhand smoke exposure at home, and nicotine addiction among adolescent smokers

INTRODUCTION Smoking family predicts adolescent smoking, but whether the level of nicotine addiction is affected by exposure to secondhand smoke (SHS) is unclear. We investigated the associations of smoking family and SHS exposure at home with morning smoking and heavier smoking among Chinese adolescent smokers. METHODS In a school-based anonymous survey, 2182 adolescent smokers reported their smoking behaviors, smoking status of family members and peers, and SHS exposure at home and outside home in the past 7 days. Families with one or more smoking members (excluding the subject) were classified as smoking families and otherwise as non-smoking families. Smoking or wanting to smoke first thing in the morning (morning smoking), and consuming more cigarettes (heavier smoking) denoted higher levels of nicotine addiction. Regression analysis yielded adjusted odds ratios (AORs) for morning smoking and β-coefficients for heavier smoking adjusting for potential confounders. RESULTS Living with siblings and other co-residing family members who smoked was significantly associated with morning smoking and heavier smoking. Compared with non-smoking families without SHS exposure at home, the AORs (95% CI) for morning smoking were 0.99 (0.76 to 1.29) for 0 day/week, 1.19 (0.95 to 1.50) for 1-3 days/week, 1.76 (1.41 to 2.21) for 4-7 days/week (p for trend <0.001) and 1.50 (1.23 to 1.83) for any days/week of SHS exposure at home in smoking families. Similarly, 4-6 days/week of SHS exposure at home significantly predicted heavier smoking. CONCLUSION Living with smoking family members and SHS exposure at home are associated with nicotine addiction in Chinese adolescent smokers.

The Use of Stunkard’s Figure Rating Scale to Identify Underweight and Overweight in Chinese Adolescents

Background To compare the performance of Stunkard’s current body size (CBS) with self-reported body mass index (BMI), waist circumference (WC) and waist to stature ratio (WSR) in predicting weight status in Chinese adolescents, and to determine the CBS cutoffs for overweight/obesity and underweight. Methodology This cross-sectional study was conducted in a sample of 5,418 secondary school students (45.2% boys; mean age 14.7 years). Height and weight were measured by trained teachers or researchers. Subjects were classified as underweight, normal weight, or overweight/obese according to the International Obesity Task Force cutoffs. Subjects were asked to select the figure that best resembled their CBS on the Stunkard’s figure rating scale. Self-reported height, weight, WC and WSR were also obtained. The performance of CBS, self-reported BMI, WC and WSR as a weight status indicator was analysed by sex-specific receiver operating characteristic curves. The optimal CBS cutoffs for underweight and overweight/obesity were determined based on the Youden Index. Principal Findings Apart from self-reported BMI, CBS had the greatest area under curve (AUC) for underweight in boys (0.82) and girls (0.81). For overweight/obesity, CBS also had a greater AUC (0.85) than self-reported WC and WSR in boys, and an AUC (0.81) comparable to self-reported WC and WSR in girls. In general, CBS values of 3 and 5 appeared to be the optimal cutoffs for underweight and overweight/obesity, respectively, in different sex-age subgroups. Conclusions/Significance CBS is a potentially useful indicator to assess weight status of adolescents when measured and self-reported BMI are not available.

Smoking Family, Secondhand Smoke Exposure at Home, and Quitting in Adolescent Smokers

INTRODUCTION This study investigated the associations of smoking family and secondhand smoke (SHS) exposure at home with quit attempts and smoking cessation among adolescents. METHODS Students from 85 randomly selected secondary schools in Hong Kong were surveyed using an anonymous self-administered questionnaire on SHS exposure at home and outside the home in the past 7 days, quit attempts, smoking cessation, sociodemographic characteristics, and smoking status of family members and peers. Families with 1 or more smoking members (excluding the subject) were classified as smoking families and otherwise as nonsmoking families. Logistic regression yielded adjusted odds ratios (AORs) for quit attempts and smoking cessation in smoking families with or without SHS exposure at home compared with nonsmoking families. RESULTS Of 4,361 students who had smoked in the past 12 months, 70.3% were living with smokers and 52.8% were exposed to SHS at home. Compared with nonsmoking families, the AORs (95% CI) for making at least 1 quit attempt in the past 12 months were 0.80 (0.61-1.05) for 0 day, 0.80 (0.63-1.04) for 1-3 days, and 0.65 (0.50-0.86) for 4-7 days of SHS exposure at home. The corresponding AORs (95% CI) for smoking cessation were 0.58 (0.48-0.70), 0.45 (0.35-0.58), and 0.49 (0.41-0.60) (p for trend <.001). Any SHS exposure at home was associated with 28% and 53% lower odds of quit attempts and smoking cessation, respectively. CONCLUSIONS Living with smoker(s) and especially being exposed to SHS at home may hinder quit attempts and smoking cessation among Chinese adolescent smokers.