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Biomedical subjects

Y B Cheung

Publications and source records attributed to Y B Cheung.

35 records · Page 2Linked to original sources
PubMed2001

Association between size at birth, paediatric diarrhoeal incidence and postnatal growth.

UNLABELLED: This study tests the hypothesis that size at birth is associated with diarrhoeal incidence from birth to 24 mo of age, and the hypothesis that diarrhoeal incidence from birth to 24 mo is associated with body size at age 24 mo. This is a longitudinal study of 1476 infants born in Lahore. Pakistan, in 1984-1987. Diarrhoeal incidence was enumerated monthly. A generalized estimating equations approach with Poisson regression showed that birthlength standard deviation score (SDS) and ponderal index at birth (rate ratio = 1.01 and 1.00; each p > 0.05) were not significantly associated with diarrhoeal incidence. Multiple linear regression showed that diarrhoeal incidence was significantly associated with weight SDS and body mass index at 24 mo (regression coefficient or beta = -0.58 and -1.02: each p < 0.05). but not with height SDS (beta = -0.10: p > 0.05). The associations were mainly due to a transient effect of diarrhoea in the period 18-24 mo. CONCLUSION: Prevention of low birthweight is unlikely to have an impact on diarrhoeal incidence in infants. Control of diarrhoeal incidence may not improve the growth of infants in developing countries.

Birth Weight↗
PubMed2001

Fetal growth, early postnatal growth and motor development in Pakistani infants.

BACKGROUND: Studies have often compared the postnatal motor development of 'small' versus 'normal' newborns. Not much is known about the associations between a broad spectrum of size at birth and motor development. The effect of early postnatal growth on motor development is little researched. Growth failure in terms of shortness and thinness should be differentiated, but not many studies have the data for this analysis. METHODS: This is a longitudinal study of infants born in Lahore, Pakistan, between 1984 and 1987. Age at commencement of independent walking and age at 'building a 3-cube tower' were taken as indicators of gross and fine motor development, respectively. Size at birth was captured by length and thinness as continuous variables; postnatal growth from birth to 6 months of age was measured by changes in length and thinness. Adjustment for covariates and handling of censored cases were performed by generalized log gamma regression. RESULTS: Thinness at birth and postnatal stunting and wasting had a linear, inverse association with gross motor development (each P < 0.05). Birth length had a non-linear, inverse association with this outcome (P < 0.05). Birth length, thinness at birth and postnatal wasting had a linear, inverse association with fine motor development (each P < 0.05). CONCLUSION: Both fetal and early postnatal growth over a broad spectrum may affect infants' motor development. It is not just the babies who were very small at birth that suffered. Birth length appeared to be more influential than other anthropometric indicators.

Child Development↗
PubMed2001

The need for collaboration between clinicians and statisticians: some experience and examples.

INTRODUCTION: Very often we see poor communication and collaboration between clinicians and statisticians. Both sides may fail to realise the importance of a truly collaborative effort. In this paper we give examples to illustrate some problems clinicians and statisticians may encounter when they do not have the full support of each other. The aim is to convince both parties the importance of a truly collaborative effort. METHODS: Real examples in various medical research areas are drawn from the authors' practical experience for illustration. The examples cover various research aspects such as the use of computer software, regression analysis and interpretation of findings. RESULTS: Superficial collaboration between clinicians and statisticians may lead to serious problems and sub-optimal research practice that may not be obvious in the first sight. Some of the barriers to effective communication and collaboration are discussed. CONCLUSIONS: On the one hand, robust statistical practice is vital in many medical research projects. On the other hand, medical thinking is important in the formulation and application of statistical strategies. Statistical inputs should be integrated into medical research projects throughout the whole research process. Sporadic contacts between clinicians and statisticians are not enough. Both parties must learn to communicate more effectively and to be willing to collaborate with each other.

Clinical Medicine↗
PubMed2000

Mortality of twins and singletons by gestational age: a varying-coefficient approach.

This study used data from the Swedish Medical Birth Registry between 1982 and 1995 to address the question of whether there is higher mortality in twins in relation to singletons of the same gestational age and to examine the optimal gestational age range for twins. A "varying-coefficient approach" was adopted to estimate the gestational age-specific relative and absolute risks of mortality in twins and singletons, adjusting for size at birth and risk factors of short gestational duration. The models showed that twins born between 29 and 37 weeks of gestation had lower mortality than did singletons of the same gestational age. Twins born at older gestational age had higher mortality than did their singleton counterparts, because longer gestational duration was more advantageous to singletons than to twins. Without adjustment for size at birth, there was an upturn of mortality in twins born after 38 weeks. It is postulated that twins have better health than singletons initially, but they could not enjoy the benefit of a longer gestational duration as much as singletons could. The optimal gestational age for twins appeared to be 37-39 weeks according to neonatal and infant mortality.

Age Distribution↗
PubMed2000

Marital status and mortality in British women: a longitudinal study.

BACKGROUND: Most previous studies on marital status and mortality did not adjust for the effect of 'marital selection'. Little research has been done about the relation between marital status and mortality in British women, with the exception of research on bereavement. METHODS: Subjects consisted of women aged > or = 35 in a longitudinal study of a nationally representative sample. Marital status and covariates were enumerated at a baseline interview in 1984/85 and a follow-up interview in 1991/92. Death data up to May 1997 were obtained from the National Health Service Central Register. Cox regression was used to estimate hazard ratios (HR) for the single, divorced and widowed states in relation to the married state. RESULTS: Having adjusted for age and martial selection factors, being single (HR = 1.45) was significantly associated with higher all-cause mortality. Being divorced and being widowed showed no excess mortality risk (each HR = 1.09). CONCLUSIONS: Being single was associated with higher mortality. A causal interpretation is plausible. Being divorced and being widowed were not associated with higher mortality.

Adult↗
PubMed2000

Fetal growth and early postnatal growth are related to blood pressure in adults.

It is commonly agreed that birth weight is associated with blood pressure in adults. However, not much is known about birth length, ponderal index, and early postnatal growth, whose effects on adult blood pressure, if any, can affect the interpretation of the birth weight-blood pressure association. This study examined the association between fetal growth, early postnatal growth, and blood pressure in Chinese adults. One hundred twenty-two subjects born in Hong Kong in 1967 were followed from birth to age 30 years. Multiple linear regression was used to analyze the association between size at birth, postnatal changes in body size, and systolic and diastolic blood pressure at age 30 years. Having adjusted for potential confounders and each other explanatory variable, it is found that birth length standard deviation score (regression coefficient or beta=-3.2), ponderal index at birth (beta=-1.8), and postnatal changes in ponderal index from age 6 months to 18 months (beta=-2.2) were inversely associated with systolic blood pressure (each P<0.05). Postnatal changes in length standard deviation score were not significantly associated with systolic blood pressure. Birth length standard deviation score was inversely associated with diastolic blood pressure at age 30 years (beta=-2.6; P<0.05). Other anthropometric variables were not associated with diastolic blood pressure. The results support the hypotheses that both fetal growth and early postnatal growth may have a long-term impact on blood pressure in adults. It also highlights the importance of differentiating length and weight for length.

Adolescent↗
PubMed1999

The impact of water supplies and sanitation on growth in Chinese children.

In many developing countries, improvement in water supplies has not been supplemented by improvement in sanitation facilities. Moreover, health education is rarely included in environmental hygiene programmes. Community health workers need to know if water supplies and sanitation have independent or complementary effects on health. This study analysed the weight data of 1,045 Chinese children aged 60 months or below. Regression models with interaction terms were tested against a model with main effects only. There was no evidence of interaction between water supplies and sanitation measures. The results show that water supplies and toilet facilities had independent associations with growth. Improved water source (P = 0.01) and flush-toilet (P = 0.06) were found positively associated with the children's weight. Presence of excreta in the home had a negative, but not statistically significant, association with weight.

Body Weight↗
PubMed1998

Can marital selection explain the differences in health between married and divorced people? From a longitudinal study of a British birth cohort.

In view of the rising divorce rates, the impact of divorce on health has an increasing importance in public health. The differentials in health between the married and the divorced may be explained by 'marital selection' and 'marital protection'. Using longitudinal data from a study of the 1958 British birth cohort, factors that select people into divorce were identified from the areas of socio-economic status, health, and attractiveness, which included physical attractiveness, health-related behaviour and temperament. Evidence for both positive and adverse selection is found. The different sets of selection factors for females and males appear to be in line with gender role expectations. The health differentials between married and divorced men were weak and can be explained away by the selection factors. Having controlled for the selection effects, there were still significant associations between divorce and physical and psychological health in women. Though these unexplained differentials cannot be definitely interpreted as the consequences of marital dissolution, this interpretation remains plausible.

Adult↗
PubMed1998

Accidents, assaults, and marital status.

Marriage may reduce the risk of accidents and assaults by promoting social control of health behavior. This study examines the impact of marital status on non-fatal accidents and assaults in young British women. Data is drawn from a large cohort study of the people born in 1958. Rate ratios of overall and specific incidence of non-fatal accidents and assaults are determined by negative binomial regression, with adjustment for socio-economic and behavioral confounders. The null hypothesis of no association between marital status and incidence of non-fatal accidents and assaults is rejected. It is suggested that, independent of parental status, more exposure to marriage and less exposure to marital dissolution may reduce accidents and assaults.

Accidents↗
PubMed1998

Health and adverse selection into marriage: evidence from a study of the 1958 British birth cohort.

Despite much research on the relationship between marital status and health, the confounding effects of marital selection are not well understood. Even less is known about 'adverse selection', the phenomenon that people with poor health or health related attributes have a higher chance of marriage. Using data from the National Child Development Study, a longitudinal study of the 1958 British birth cohort, this paper examines the effects of factors that can select single people into early or later marriages. The selection factors are from three domains, namely, health status, socioeconomic status, and risk-taking behaviour. It is found that, from age 16-23 y, adverse selection is prevalent. People from a lower socio-economic background and smokers are more likely to be married. This has the potential to suppress any association between marriage and health. Meanwhile, men with medical problems are less likely to marry. At ages from 23-33 y, adverse selection reduces and those who have better life chances are more likely to get married. This has the potential of creating a spurious relation between marriage and health. These findings shed light on the understanding of the confounding effects of marital selection according to different life stages.

Adolescent↗
PubMedDate not supplied

Secular change in growth over one decade (1980-1990) in Shanghai infants.

The aims of this study were to describe secular changes in body size in Shanghai infants, to compare the growth pattern between Shanghai children and Swedish children, and to explore the association of growth rate with parental body size, feeding practice and child health status. The study series consisted of 6,018 longitudinally followed full-term children, born between 1st January 1980 and 31st December 1990 in Fenglin Community, Shanghai. The data clearly show a positive secular trend in growth in Shanghai over the decade of observation; at 12 months, the mean increase in weight and length were 0.32 kg and 0.64 cm, and at 24 months they were 0.54 kg and 1.29 cm. The general growth pattern observed in the children in comparison with the Swedish reference was of fast growth in the first few months of life, and faltering between 9 and 24 months of age. Age at introduction of solid food, weaning age and parental body size were related to growth velocity in the first two years. There was little cumulative effect of diarrhoea on growth in the first two years of life.

Body Height↗
PubMedDate not supplied

Benn Index at birth is associated with postnatal linear growth.

While previous research has suggested that body thinness is related to subsequent linear growth in children, it is unclear whether thinness at birth is related to linear growth in newborns and catch-up growth in small-forgestational age newborns. Drawing on data from a longitudinal growth study of 3,650 full-term Swedish babies, this study examines linear growth from birth to 6 months of age in three groups of newborns with short (< -2 SDS), appropriate (-2 to 2 SDS) and long (> 2 SDS) body length for gestational age. Among infants short at birth, the Benn Index (kg/m2.69) at birth was not related to the odds of short stature (< -2 SDS) at age 6 months (odds ratio = 1.03; p > 0.10). Nonetheless, the Benn Index was positively related to growth velocity in the first 6 months of life in the short (p = 0.060), appropriate (p < 0.05), and tall (p < 0.05) for gestational age newborns. Use of the Ponderal Index (kg/m3) would give similar results. The findings suggest that nutritional status at birth is related to linear growth velocity in newborns.

Birth Weight↗