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Biomedical subjects

Y B Cheung

Publications and source records attributed to Y B Cheung.

At least 19 recordsLinked to original sources
PubMed2005

Discriminative ability of the short-form 36 health survey: a tale of two versions.

BACKGROUND AND OBJECTIVES: Previous studies suggested that the Chinese version of the Short-Form 36 Health Survey (SF-36) had smaller variability in the physical functioning (PF) and physical component summary (PCS) scores than the English SF-36. This may translate into differences in discriminative ability and sample size requirement. MATERIALS AND METHODS: Data were drawn from a community-based survey and a randomised crossover study of Singaporeans bilingual in the Chinese and English languages. The abilities of the two PF and PCS versions in discriminating subjects who reported chronic illness and acute disease symptoms versus those who did not were compared. RESULTS: In all four comparisons (i.e. two health criteria in two studies) the Chinese version of PF showed a larger effect size than the English version. In three out of four comparisons the Chinese version of PCS showed a larger effect size than the English version. CONCLUSIONS: The Chinese version appeared more efficient in detecting a statistically significant difference between groups. Other factors being the same, the Chinese SF-36 may require a smaller sample size than the English SF-36 for the studies of physical aspects of health-related quality of life.

Activities of Daily Living↗
PubMed2005

Can patients with early-stage diffuse large B-cell lymphoma be treated without bone marrow biopsy?

BACKGROUND: Data on the incidence of bone marrow (BM) involvement in early-stage diffuse large B-cell lymphoma (DLBCL) are lacking. Although BM biopsy is a safe procedure, it is often poorly tolerated. This analysis aims to assess the incidence of BM involvement and to identify parameters predicting BM involvement in early-stage DLBCL. PATIENTS AND METHODS: One hundred and ninety-two patients with radiological stages 1 and 2 disease were analysed. The data collected were age, sex, presence of B symptoms, white blood cell (WBC) count, platelet count, haemoglobin (Hb), serum lactate dehydrogenase level, serum beta(2)-microglobulin level, presence of extranodal disease, and the presence of bulky disease (defined as >7 cm). RESULTS: Overall incidence of BM involvement was 3.6%. Hb < 10 g/dl (P=0.02), WBC count < 4 x 10(9)/l (P=0.007) and bulky disease (P=0.06) were found to be predictive of BM involvement. Among the 120 patients without any of these three factors, only one patient had BM involvement (0.83%; 95% confidence interval 0.02% to 4.6%). The absence of all three factors gave a negative predictive value of 99.2%. Overall 3-year survival for patients without all three risk factors was 80%. CONCLUSIONS: BM biopsy may be safely omitted in selected patients with early-stage DLBCL.

Bone Marrow Examination↗
PubMed2005

Risk perception is affected by modes of risk presentation among Singaporeans.

INTRODUCTION: Not much is known about how Singaporeans perceive and react to risk presentation. There is no consensus on whether the European Union guidelines for describing the risk of side effects are valid. This study investigated the effect of different modes of risk presentation on how Singaporeans perceive and react to medical risk. Furthermore, we investigated the practical usage of qualitative phrases, the European Union's adjectives in particular, in describing levels of risk. MATERIALS AND METHODS: A hypothetical situation about the risk of side effects of an influenza vaccine was presented in either a probability format (i.e., 5%; n = 42) or a frequency format (i.e., 1 out of 20; n = 43). The 2 versions of questionnaire were handed out in an alternate order to a convenience sample of 47 healthcare professionals and 38 university students. RESULTS: Respondents presented with a "5% risk" were more likely to describe the risk as "uncommon" or "rare", as compared to respondents presented with a risk of "one out of twenty" (P <0.01). Furthermore, the former showed more willingness to accept the influenza vaccine described in the hypothetical situation than in the latter, but this was not statistically different (67% versus 54%; P >0.1). CONCLUSIONS: Modes of risk presentation affect how people perceive risk, even among people who are highly educated.

Adult↗
PubMed2005

Acceptance of prophylactic surgery and chemoprevention of cancer in Singapore - a survey.

INTRODUCTION: In addition to surveillance practices, chemoprevention and prophylactic surgery can reduce the risk of cancer in individuals at high risk. Sociocultural factors may have a role to play in such decision making. Little is known regarding the factors that play a role in decision making in Singapore. MATERIALS AND METHODS: One hundred and two individuals at normal risk completed a questionnaire on the concept of chemoprevention and prophylactic surgery. The results were analysed using the convenience sampling method. RESULTS: Participants were mostly Chinese (94.1%). More than 90% of the respondents answered the section on prophylactic surgery and chemoprevention. Thirty-eight individuals (41.3%) would not consider prophylactic surgery, while 42 (45.7%) would not consider prophylactic surgery now but might consider it in the future. Twenty-five individuals (26.9%) would not consider chemoprevention by taking a medication, 57% would not consider it now but might in the future. CONCLUSION: A cross-sectional public view suggests that medical prophylaxis is likely to be more acceptable to the general public compared to surgical prophylaxis.

Adolescent↗
PubMed2005

Concurrent chemoradiotherapy followed by surgery in locally advanced squamous cell carcinoma of the oesophagus: a single centre experience.

INTRODUCTION: Data on combined modality treatment for locally advanced squamous cell carcinoma of the oesophagus involving Asian patients are limited. MATERIALS AND METHODS: A retrospective study of 56 consecutive patients with this condition treated with concurrent chemoradiotherapy followed by surgery in a single tertiary institution in Singapore was performed. RESULTS: The median overall survival of the entire cohort was 14.1 months [95% confidence interval (CI); range, 8.6 to 19.6 months]. In patients who underwent successful oesophagectomy after chemoradiotherapy (n = 17), the median survival was 27.8 months compared to 9.8 months for those who did not have surgery (n = 39) (P = 0.046, log-rank test). The median time to first relapse for the entire cohort was 16.1 months (95% CI, 7.7 to 24.5 months). The time to first relapse was 23.9 months in the subgroup of patients with successful surgery and 12.1 months in the group which did not (P = 0.147, log-rank test). The high proportion of patients who were medically unfit for surgery or declined surgery may have conferred a selection bias. CONCLUSION: Concurrent chemoradiotherapy followed by surgery is feasible in selected patients. The benefit of adding of surgery to chemoradiotherapy is still controversial and we await the results of randomised controlled trials comparing chemoradiotherapy with surgery versus chemoradiotherapy alone.

Carcinoma, Squamous Cell↗
PubMed2004

Modelling variability of quality of life scores: a study of questionnaire version and bilingualism.

BACKGROUND AND OBJECTIVES: Modelling variability of quality of life scores can not only improve our understanding of the characteristics of the measurement tools, but also shed light on sample size requirements. Although the English and Chinese versions of the Short Form 36 Health Survey (SF-36) are commonly considered equivalent, they have not been compared in terms of variability. Furthermore, bilingual and monolingual persons may differ in cognition and responses to questionnaires. METHODS: In a community-based survey of quality of life in Singapore, a society where both English and Chinese are widely used and bilingualism is prevalent, 2590 respondents answered either version of the SF-36. We studied the impact of questionnaire version and bilingualism on the variability of SF-36 scores by regression modelling, with adjustment for covariates. RESULTS: The Chinese version had smaller variances in the physical functioning (PF) and the physical component summary scores than the English version. The variance ratios (VRs) were respectively 0.32 and 0.60 (each p < 0.01), controlling for covariates. Bilingualism was not associated with variability in SF-36 scores except PF (VR = 0.78; p < 0.05). CONCLUSIONS: As a result of a smaller variance, using the Chinese version of SF-36 among bilingual Chinese people may require a smaller sample size than using the English version.

Adult↗
PubMed2004

Birthweight and psychological distress in adult twins: a longitudinal study.

AIM: To assess the relation between birthweight and psychological distress as measured by the Malaise Inventory in adult twins. METHODS: Data were drawn from the 1958 British birth cohort study, which included twins followed from birth to age 42 y. We examined the relation between birthweight and psychological distress at ages 23, 33 and 42 y measured by the psychological scale of the Malaise Inventory. Analyses were performed both between subjects (n = 282) and within twin pairs (n = 112). The generalized estimating equations approach was used to handle the repeated measurements. RESULTS: Between the 282 twins, the difference in psychological distress score was -0.45 (95% confidence interval -0.74 to -0.15) per Z-score increase in birthweight-for-gestational age. Within twin pairs, the heavier co-twins tended to have a psychological distress score lower than that of their lighter co-twins, the mean difference being -0.35 (-0.78 to 0.09). CONCLUSION: Results from the between-subject analysis agreed with previous findings from adult singletons that psychological health is related to birthweight. The within-pair analysis suggested a similar relation but did not attain statistical significance.

Adult↗
PubMed2003

Measuring quality of life in Chinese cancer patients: a new version of the Functional Living Index for Cancer (Chinese).

INTRODUCTION: Since its translation into Chinese, the Functional Living Index for Cancer (FLIC) has not been widely received due to some of its difficulties. We modified its visual analogue scale (VAS) to an ordered categorical scale and changed some of the wording in the instrument. This study examined the measurement properties of the modified FLIC. MATERIALS AND METHODS: The modified version of FLIC and the Functional Assessment of Cancer Therapy (FACT-G Chinese version 4) were filled in by 140 patients recruited from the National Cancer Centre Singapore. The patients' FLIC scores were compared with their clinical characteristics to establish known-group validity. Convergent and divergent validity of FLIC were examined by correlation analysis with FACT-G and its sub-scales. Cronbach's alpha and relative efficiency were also examined. RESULTS: FLIC and most of its sub-scales could indicate a clear and statistically significant difference of quality of life (QOL) according to patients' performance status and treatment status. FLIC strongly correlated with FACT-G. The Physical, Psychological, and Symptoms sub-scales of FLIC converged to and diverged from FACT-G sub-scales as conceptually expected. Cronbach's alpha indicated a satisfactory level of reliability. FLIC appeared to be more efficient than FACT-G, meaning that a smaller sample size will be required for FLIC than for FACT-G to achieve the same research purpose. CONCLUSIONS: The modified version of FLIC was found to have achieved satisfactory measurement properties. This is a user-friendly alternative to the original FLIC.

China↗
PubMed2002

Association between psychological symptoms in adults and growth in early life: longitudinal follow up study.

OBJECTIVES: To test the hypothesis that birth weight for gestational age and weight gain in early childhood have a long term association with psychological distress in adults. DESIGN: Longitudinal study of 1958 birth cohort followed to age 42 years. SETTING: Population based birth cohort study. PARTICIPANTS: 9731 cohort members with valid perinatal, postnatal, and adult data. MAIN OUTCOME MEASURES: Malaise inventory scores measured at ages 23, 33, and 42 years. Generalised estimating equations approach used to analyse repeated measures. RESULTS: Psychological distress score was inversely related to birthweight z score and weight gain from birth to the age of 7 years. A unit increase in birthweight z score or childhood weight gain was associated with a mean reduction in psychological distress score of 0.10 (95% confidence interval 0.05 to 0.15) and 0.06 (0.02 to 0.10), respectively. Birth weight and weight gain were also inversely related to the odds of having a high level of psychological distress, with odds ratios being 0.90 (0.85 to 0.95) and 0.93 (0.89 to 0.98), respectively. CONCLUSIONS: Psychological health in adults is related to fetal growth and growth in early childhood.

Adult↗
PubMed2002

The influence of the Chinese zodiac on fertility in Hong Kong SAR.

The annual total of births in Hong Kong SAR fell substantially in the past 20 years; hence the total fertility rate (TFR) followed the downward trend and dropped to a low of 0.9 below replacement level in 2000. Despite the long-term downward trend, short-run increases in the annual total of births and the TFR were exhibited. Such temporary fertility increases are identified in the Dragon Years of 1988 and 2000. The phenomenon of fertility changes associated with zodiacal animal years is examined in this paper with a view to gaining some insight into whether Chinese cultural preferences and folklore beliefs might have influenced prospective parents' reproductive behaviour. The paper explains the underlying philosophy of the Chinese astrological tradition and discusses how zodiacal preferences affect fertility between 1976 and 2000. The paper also explores why zodiacal influences on Chinese fertility before 1976 did not exist. It is unquestionable that the Dragon Year preference exerts an influence on fertility of modern Chinese populations through zodiacal birth-timing motivations. Birth rate rise in the Dragon Year is due to changes in timing of births that will have little effect on cumulative fertility.

Actuarial Analysis↗
PubMed2002

Size at birth and neonatal and postneonatal mortality.

UNLABELLED: Birthweight is a crude indicator of size at birth. Some neonatologists and obstetricians have advocated the use of ponderal index and birthlength to characterize size at birth. This paper examines the associations between various size-at-birth indicators and neonatal and postneonatal mortality, with an emphasis on ponderal index and birthlength. Size at birth, gestational age and mortality data for about one million babies born alive in Sweden between 1987 and 1995 were collected from the Swedish Medical Birth Registry. A multinomial logit regression was used to estimate conditional odds ratios. Birthlength and ponderal index were independently associated with neonatal and postneonatal mortality. In the latter period, ponderal index was only weakly associated with mortality. The associations were not sensitive to exclusion of cases of congenital anomalies and adjustment for gestational age. CONCLUSION: Birthlength is strongly associated with both neonatal and postneonatal mortality; ponderal index is strongly associated with neonatal, but weakly with postneonatal mortality. The findings are consistent with previous hypotheses about a transient effect of ponderal index and a persistent effect of birthlength.

Birth Weight↗
PubMed2002

Agreement or prediction: asking and answering the right question.

INTRODUCTION: Measuring agreement and measuring predictive ability are similar but distinct problems. Failure to appreciate the conceptual and practical differences may lead clinical researchers to give the right answer to the wrong question. METHODS: We illustrate the relation and difference between measuring agreement and predictive ability in a non-technical way. We provide a real example investigating the feasibility of using preoperative breast cancer tumour size measurements to estimate postoperative histological size. The intraclass correlation and R-squared are calculated to ascertain the level of agreement and predictive ability respectively. RESULTS: Analysis of agreement and analysis of predictive ability serve different purposes. The optimal solution found in terms of agreement may be different from that found for prediction. CONCLUSIONS: A careful clarification of the goal of an investigation is important. Using an inappropriate analysis can lead to misleading results, or to results that do not really answer the research question of interest.

Anthropometry↗
PubMed2001

Parametric modelling of neonatal mortality in relation to size at birth.

We use a richly parameterized model to analyse the effects of shortness and thinness at birth on neonatal mortality in Swedish live-born singletons. The model captures the hazard of neonatal mortality according to the function alpha x exp(-gamma x t) + delta, where t represents age. Covariates are allowed to simultaneously influence the initial excess hazard, the rate of decay, and the long-term hazard. Among term newborns, birth length for gestational age had a stronger effect on the long-term hazard and a weaker effect on the initial excess hazard than the Ponderal index. The initial excess hazard associated with a low Ponderal index tended to decay quickly. Among preterm newborns, a higher birth length for gestational age was associated with lower initial and long-term hazards, and with a faster rate of decay of the initial excess hazard. In contrast, the Ponderal index was not associated with the long-term hazard. We discuss the interpretability of the model and its potential use in neonatology and medical demography. We also compare the model to a Cox model with time-dependent covariates.

Analysis of Variance↗
PubMed2001

Social patterns of birth weight in Hong Kong, 1984-1997.

Fetal growth is an indicator of social inequalities in health that may have a long-term impact persisting into later life. Little is known about the social patterns of birth weight in Hong Kong. This is a study of live-born singletons from 1984 to 1997 in a Hong Kong birth registry. Ordinary least-squares regression and logistic regression are used to analyse birth weight and low birth weight (< 2500 g), respectively. A gradient of birth weight and prevalence of low birth weight is demonstrated according to mothers' educational attainment. In relation to babies of the most educated mothers, babies of the least educated mothers had a mean deficit of 46g in birth weight and an odds ratio of 1.56 of low birth weight (each P<0.05). This social gradient was hidden unless parity was adjusted for. Unexpectedly, migrants from mainland China delivered heavier rather than lighter babies (each P<0.05). Type of living quarters and parental relation were also related to birth weight and low birth weight (each P<0.05). Continuous monitoring of the social patterns of birth weight is recommended.

Birth Weight↗
PubMed2001

Adjustment for selection bias in cohort studies: an application of a probit model with selectivity to life course epidemiology.

Sample attrition is potentially a source of bias in cohort studies. The outcome may not be observed in a considerable proportion of the subjects. This article proposes the application of a probit model with sample selection to handle the problem. Two equations are simultaneously estimated and their error terms allowed to correlate: one regressing an observed outcome on a set of baseline variables, another regressing the probability of the outcome being observed upon a set of (perhaps the same) baseline variables. The method was applied to a study of a birth cohort, half of whose members were interviewed again at age 26. Baseline variables were observed for all the subjects included. The focus was on the association between birth weight and mental health in adults. The probit model with sample selection revealed a stronger and more significant (P = 0.037) relation between birth weight and mental health than an ordinary probit regression model (P = 0.170). Interpretation and practical considerations are discussed.

Adult↗
PubMed2001

Seasonality of growth in Shanghai infants (n=4128) born in 11 consecutive years.

OBJECTIVE: To describe the seasonal growth patterns in Shanghai infants, to explore seasonal time lag between weight gain and length gain, and to investigate the long-term effect of birth season on early postnatal growth. DESIGN: Community-based longitudinal study. SETTING: Shanghai, People's Republic of China. METHOD: Children were followed up monthly from 1 to 6 months, 3 monthly from 6 to 12 months, and 6 monthly from 12 to 24 months. SUBJECTS: A total of 6018 children born between 1 January 1980 and 31 December 1990. MAIN OUTCOME MEASURES: Weight gain, length gain and change in body mass index (BMI) over the seasons of the year. RESULTS: The infants tended to grow faster in height in spring and summer, and faster in weight and BMI in autumn and winter. The seasonal effect on weight gain and length gain is largely independent. The mean length value at 1 month of age was about 2.0 cm higher in infants born in May to July than in those born in November to February. At 24 months of age this difference was reduced to about 0.7 cm. CONCLUSIONS: There is a clear and consistent seasonality in growth in Shanghai infants. The seasonality seems to act independently on weight and length. Birth month has some association with attained size, but this is reduced during the first 2 y of life.

Body Height↗