Biomedical subjects

Andy H Lee

Publications and source records attributed to Andy H Lee.

At least 37 records · Page 2Linked to original sources

PubMed2005

Quality of life profile--adolescent version: assessing the relationship of covariates to scale scores using structural equation modeling.

This study investigates the effects of covariates on adolescent quality of life (QOL) using structural equation modeling (SEM). The Quality of Life Profile--Adolescent Version, a generic 54 item self-reported questionnaire, was administered to 363 adolescents aged between 10 and 18 years who were enrolled in 20 secondary schools within metropolitan Perth, the capital of Western Australia. Previous results based on a second-order SEM provided preliminary support for measuring adolescent QOL in terms of physical health, psychological, social, environment and opportunities for growth and development. The second-order model is further enhanced in this study by incorporating covariates age, presence of a chronic condition, amount of control and perception of health. The amount of control the adolescent perceived had a significant positive impact on QOL, whereas poorer reports of health had a negative impact. However, the presence of a chronic condition was found to have little effect on QOL, while the modest inverse relationship between age and QOL was not statistically significant.

Adolescent↗

PubMed2005

A robustified modeling approach to analyze pediatric length of stay.

PURPOSE: Length of stay (LOS) is an important measure of the cost of pediatric hospitalizations, but the guidelines developed so far are not rigorously evidence-based. This study demonstrates a robust gamma mixed regression approach to analyze the positively skewed LOS variable, which has implications for future studies of pediatric health care management. METHODS: The robustified approach is applied to analyze hospital discharge data on childhood gastroenteritis in Western Australia (n=514). The model accounts for demographic characteristics and co-morbidities of the patients, as well as the dependency of LOS outcomes nested within the 58 hospitals in the State. The method is compared with the standard linear mixed regression with trimming of extreme observations. RESULTS: For the empirical application, the linear mixed regression results are sensitive to the magnitude of trimming. The identified significant factors from the robust regression model, namely infection, failure to thrive, and iron deficiency anemia are resistant to high-LOS outliers. CONCLUSIONS: Robust gamma mixed regression appears to be a suitable alternative to analyze the clustered and positively skewed pediatric LOS, without transforming and trimming the data arbitrarily.

Child, Hospitalized↗

PubMed2005

Modelling bivariate count series with excess zeros.

Bivariate time series of counts with excess zeros relative to the Poisson process are common in many bioscience applications. Failure to account for the extra zeros in the analysis may result in biased parameter estimates and misleading inferences. A class of bivariate zero-inflated Poisson autoregression models is presented to accommodate the zero-inflation and the inherent serial dependency between successive observations. An autoregressive correlation structure is assumed in the random component of the compound regression model. Parameter estimation is achieved via an EM algorithm, by maximizing an appropriate log-likelihood function to obtain residual maximum likelihood estimates. The proposed method is applied to analyze a bivariate series from an occupational health study, in which the zero-inflated injury count events are classified as either musculoskeletal or non-musculoskeletal in nature. The approach enables the evaluation of the effectiveness of a participatory ergonomics intervention at the population level, in terms of reducing the overall incidence of lost-time injury and a simultaneous decline in the two mean injury rates.

Accidents, Occupational↗

PubMed2005

Health conditions of heavy vehicle drivers involved in a crash in Western Australia: a retrospective study using linked data.

ISSUE ADDRESSED: This retrospective study investigated the health conditions of a cohort of heavy vehicle drivers involved in a crash in Western Australia. METHODS: Hospital separation records of heavy vehicle drivers admitted to hospital as a result of a road crash between 1 January 1988 and 31 December 2000 in Western Australia were analysed. Heavy vehicle drivers involved in a crash were first identified using the Western Australian Road Injury Database before linking to their hospital records. All hospital admissions for each driver admitted to hospital for a crash at least once during the study period were subsequently retrieved from the Health Services Linked Database. RESULTS: There were 146 heavy vehicle drivers in the cohort. A total of 964 distinct in-patient episodes (the collection of all hospital admissions for a single event) were recorded for these drivers, with a minimum of one and a maximum of 84 hospital in-patient episodes per driver. The mean number of in-patient episodes for each driver was seven (SD=8.44), including an in-patient episode for a heavy vehicle crash. CONCLUSION: The evidence presented for the cohort of heavy vehicle drivers hospitalised as a result of road crash confirms that these drivers are characterised with health conditions such as musculoskeletal problems and digestive disorders.

Accidents, Traffic↗

PubMed2005

Measuring preferences for delivery services in rural Vietnam.

BACKGROUND: The relatively low use of maternity services at the primary health care level in Vietnam has highlighted the need for economic evaluations of the current maternal health delivery network. This study measured willingness-to-pay for obstetric delivery preferences in rural Vietnam. METHODS: An interviewer-administered survey was conducted among 200 postpartum and 196 pregnant women, and 196 men in Quang Xuong district, Thanh Hoa province of Vietnam, using the payment card technique. RESULTS: A kappa score of 0.98 showed very good agreement between the two interviewers administering the survey. An association was found between willingness-to-pay and satisfaction with the quality of maternity services. No significant differences were found in willingness-to-pay values between prenatal and postpartum groups, and between male and female participants. CONCLUSIONS: The study demonstrates that the willingness-to-pay instrument is a feasible tool, and is relatively reliable to measure the benefit of different alternatives of delivery services in rural Vietnam. For wider application of the instrument, its validity should be investigated further. Meanwhile, health care managers and decision makers should be encouraged to apply the instrument in the evaluation of maternal health programs.

Adult↗

PubMed2005

Multilevel modelling of hospitalisations for recurrent diarrhoeal disease in Aboriginal and non-Aboriginal infants and young children in Western Australia.

A multilevel proportional hazards model was used to determine the prognostic factors affecting hospitalisations for recurrent diarrhoeal disease in infants and young children. All infants born in 1996 who had index gastroenteritis admission to Western Australian (WA) hospitals during their first year of life were included in our study cohort (n = 486). There were 618 hospital admissions for infectious diarrhoea over the 6-year follow-up period. Aboriginal children stayed significantly longer in hospital than their non-Aboriginal peers, and comorbidities such as dehydration, gastrointestinal sugar intolerance, failure to thrive, iron deficiency anaemia and certain infections (genitourinary, scabies and/or otitis media) were all significantly associated with the delayed discharge of patients. Substantial variations among patients (variance = 0.660) and between health service regions of WA (variance = 0.296) were found. Over 30% of the total variation could be attributed to the heterogeneity between health districts. For any two patients in the same health district, the within-region (intraclass) correlation was estimated to be 0.309. In the absence of detailed socio-demographic data, application of the standard survival procedure may lead to incorrect inferences due to regional clustering and repeated observations on individuals. By accounting for latent patient and regional effects, the multilevel analysis clearly confirmed the high burden of infectious diarrhoea among Aboriginal infants and children, and their much longer hospital stays. Coexisting morbidities contributed to the prolonged and recurrent hospitalisations. Findings of this epidemiological study indicated the need of multifaceted clinical disease prevention and hygiene promotion strategies to control the disease.

Anemia, Iron-Deficiency↗

PubMed2005

Household hygiene practices in relation to dampness at home and current wheezing and rhino-conjunctivitis among school age children.

Good household hygiene practices may improve indoor air quality in the domestic environment. Conversely, a 'hygiene hypothesis' is challenging the importance of hygiene and sanitation at home. This study aims to investigate the relationship between household hygiene practices and dampness at home and current wheezing, asthma and other allergic conditions among Australian children. Nine hundred and ninety-six children from four primary schools in Perth, Western Australia, were recruited for a domestic environmental and health survey during March and April of 2002. The results showed that high cleanliness scores were negatively associated with moulds at home before and after adjustment for age of dwelling (p < 0.001). High ventilation scores were inversely related with damp patches, condensation and moulds at home (p < 0.05). However, households with high cleanliness scores appeared to have significantly higher prevalence of current wheezing (p < 0.05) and current rhino-conjunctivitis (p < 0.05) in children. The association remained even after controlling for confounders such as age and gender of children, asthma history of parents, passive smoking and dampness at home.

Adolescent↗

PubMed2005

Determinants of breast-feeding within the first 6 months post-partum in rural Vietnam.

OBJECTIVE: This study explored the determinants of breast-feeding practices within the first 6 months post-partum among women residing in rural Vietnam. METHODS: The study was conducted in Quang Xuong district, in the Thanh Hoa Province of Vietnam. In the first phase, 463 women were prospectively studied at weeks 1, 16 and 24 post-partum. During the second phase, 16 focus group discussions were undertaken to obtain complementary information. RESULTS: Exclusive breast-feeding dropped from 83.6% at week 1 to 43.6% at week 16 and by week 24, no infant was exclusively breast-fed. A logistic regression analysis found 'mother's education level', 'mother's decision-making on breast-feeding', 'mother's comfort to breast-feed in public places', 'father's occupation', 'feeding preference of father' and 'having sufficient food for the family' significantly influenced the exclusive breast-feeding practice. Qualitative data provided in-depth information on factors relating to mother, infant, close relatives and providers. CONCLUSION: Providing appropriate training and supportive supervision on breast-feeding counselling to health workers and supporting working mothers to exclusively breast-feed their infants through community mobilization were recommended to improve breast-feeding in rural Vietnam.

Adult↗

PubMed2005

Introduction of complementary food to infants within the first six months postpartum in rural Vietnam.

AIM: To document the introduction of complementary food and factors influencing the decision to feed infants with solid food within 6 mo postpartum in rural Vietnam. METHODS: A longitudinal study of 463 women who gave birth during August-October 2002 was conducted. RESULTS: An early introduction of complementary food was found, which increased from 16.4% at week 1 to 56.5% at week 16 and nearly 100% at week 24. Home-cooked solid food was introduced by 4.8%, 40.9% and 74.3% of women at weeks 1, 16 and 24, respectively. Logistic regression analysis found that at week 24 postpartum, it was less likely for the infant to be fed with solid food if the mother was a farmer (OR 0.52, 95% CI: 0.18-0.95) and passed secondary school (OR 0.28, 95% CI: 0.10-0.54), whose husband was satisfied with the infant's sex (OR 0.30, 95% CI: 0.17-0.53), her mother-in-law preferred exclusive breastfeeding (OR 0.18, 95% CI: 0.04-0.75), or her friends practised exclusive breastfeeding (OR 0.41, 95% CI: 0.16-1.10). However, infants were likely to be fed with solid food when their parents had higher income and lived independently (OR 1.76, 95% CI: 1.01-3.06). CONCLUSION: Community mobilization for sharing the workload with women could help them to cope with employment and breastfeeding.

Adult↗

PubMed2005

Body mass index in relation to ovarian cancer survival.

Evidence for an association between indicators of adiposity and survival after ovarian cancer has been inconsistent. A prospective cohort study was conducted in China to examine the relationship between ovarian cancer survival and body mass index (BMI). From the 214 patients recruited in 1999 to 2000 with histopathologically confirmed invasive epithelial ovarian cancer, 207 patients or their close relatives (96.7% of cases) were traced and followed to 2003. Deaths were recorded and Cox proportional hazards regression was used to obtain hazard ratios (HR) and 95% confidence intervals (95% CI) from multivariate models. Reduced survival was observed among patients with BMI > or = 25 kg/m(2) at 5 years before diagnosis (P = 0.001). There were 98 (59.8%) of 164 patients with BMI <25 kg/m(2) survived to the time of interview compared with only 15 women (34.9%) among the 43 patients whose BMI was > or =25 kg/m(2). The HRs significantly increased with higher BMI at 5 years before diagnosis but not at diagnosis nor at age 21 years. The adjusted HR was 2.33 (95% CI, 1.12-4.87) for BMI of > or =25 versus <20 kg/m(2), with a significant dose-response relationship. The HR was 3.31 (95% CI, 1.26-8.73) among patients who had been overweight or obese at age 21 years, but a linear dose-response was not found. We conclude that premorbid BMI may have independent prognostic significance in ovarian cancer.

Adiposity↗

PubMed2005

Lycopene and prostate cancer: emerging evidence.

Prostate cancer has the third highest incidence of all cancers in men worldwide and is the most common neoplasm diagnosed among men beyond middle age in many developed countries. Mounting evidence surrounding the consumption of tomato products has shown promise for the prevention of prostate cancer. This protective effect has more recently been linked to lycopene, the most abundant carotenoid in tomatoes. Lycopene is a natural pigment that gives the red color to many foods. In Western countries, 85% of dietary lycopene can be attributed to the consumption of tomato-based products. This article reviews emerging evidence from epidemiologic studies for the role of lycopene in prostate cancer prevention. The majority of evidence currently comes from observational studies, but recent human clinical trials and animal studies have provided additional support. Growing evidence on the biologic mechanisms of lycopene in prostate cancer prevention also confirm the epidemiologic findings.

Animals↗

PubMed2005

Possible role for green tea in ovarian cancer prevention.

Ovarian cancer is the leading cause of death from gynecologic cancer. Tea, especially green tea, has shown promise in the prevention of several cancers. Green tea contains a number of compounds, including polyphenols, that have chemopreventive properties. There is much evidence from in vitro and animal studies suggesting that components of tea are associated with decreased risk or progression of ovarian cancer. However, epidemiologic studies have generated inconsistent results. Recent research conducted in China reported reduced risk of ovarian cancer and increased survival post diagnosis with green tea consumption. This review presents emerging evidence and the authors' perspectives on the role of green tea in ovarian cancer prevention.

Animals↗

PubMed2004

Green tea consumption enhances survival of epithelial ovarian cancer.

Our study investigates whether tea consumption can enhance the survival of patients with epithelial ovarian cancer, a prospective cohort study was conducted in Hangzhou, China. The cohort comprised 254 patients recruited during 1999-2000 with histopathologically confirmed epithelial ovarian cancer and was followed up for a minimum of 3 years. Two hundred forty four (96.1%) of the cohort or their close relatives were traced. The variables examined included their survival time and the frequency and quantity of tea consumed post-diagnosis. The actual number of deaths was obtained and Cox proportional hazards models were used to obtain hazard ratios and associated 95% confidence intervals (CI), adjusting for age at diagnosis, locality, BMI, parity, FIGO stage, histologic grade of differentiation, cytology of ascites, residual tumour and chemotherapeutic status. The survival experience was different between tea drinkers and non-drinkers (p < 0.001). There were 81 (77.9%) of 104 tea-drinkers who survived to the time of interview, compared to only 67 women (47.9%) still alive among the 140 non-drinkers. Compared to non-drinkers, the adjusted hazard ratios were 0.55 (95% CI = 0.34-0.90) for tea-drinkers, 0.43 (95% CI = 0.20-0.92) for consuming at least 1 cup of green tea/day, 0.44 (95% CI = 0.22-0.90) for brewing 1 batch or more of green tea/day, 0.40 (95% CI = 0.18-0.90) for consuming more than 500 g of dried tea leaves/year, and 0.38 (95% CI = 0.15-0.97) for consuming at least 2 g of dried tea leaves/batch. The corresponding dose-response relationships were significant (p < 0.05). We conclude that increasing the consumption of green tea post-diagnosis may enhance epithelial ovarian cancer survival.

Adenocarcinoma, Clear Cell↗

PubMed2004

Snoring in primary school children and domestic environment: a Perth school based study.

BACKGROUND: The home is the predominant environment for exposure to many environmental irritants such as air pollutants and allergens. Exposure to common indoor irritants including volatile organic compounds, formaldehyde and nitrogen dioxide, may increase the risk of snoring for children. The aim of this study was to investigate domestic environmental factors associated with snoring in children. METHODS: A school-based respiratory survey was administered during March and April of 2002. Nine hundred and ninety six children from four primary schools within the Perth metropolitan area were recruited for the study. A sub-group of 88 children aged 4-6 years were further selected from this sample for domestic air pollutant assessment. RESULTS: The prevalences of infrequent snoring and habitual snoring in primary school children were 24.9% and 15.2% respectively. Passive smoking was found to be a significant risk factor for habitual snoring (odds ratio (OR) = 1.77; 95% confidence interval (CI): 1.20-2.61), while having pets at home appeared to be protective against habitual snoring (OR = 0.58; 95% CI: 0.37-0.92). Domestic pollutant assessments showed that the prevalence of snoring was significantly associated with exposure to nitrogen dioxide during winter. Relative to the low exposure category (<30 microg/m3), the adjusted ORs of snoring by children with medium (30 - 60 microg/m3) and high exposures (> 60 microg/m3) to NO2 were 2.5 (95% CI: 0.7-8.7) and 4.5 (95% CI: 1.4-14.3) respectively. The corresponding linear dose-response trend was also significant (P = 0.011). CONCLUSION: Snoring is common in primary school children. Domestic environments may play a significant role in the increased prevalence of snoring. Exposure to nitrogen dioxide in domestic environment is associated with snoring in children.

Air Pollutants↗

PubMed2004

Sensitivity of score tests for zero-inflation in count data.

In many biomedical applications, count data have a large proportion of zeros and the zero-inflated Poisson regression (ZIP) model may be appropriate. A popular score test for zero-inflation, comparing the ZIP model to a standard Poisson regression model, was given by van den Broek. Similarly, for count data that exhibit extra zeros and are simultaneously overdispersed, a score test for testing the ZIP model against a zero-inflated negative binomial alternative was proposed by Ridout, Hinde and Demétrio. However, these test statistics are sensitive to anomalous cases in the data, and incorrect inferences concerning the choice of model may be drawn. In this paper, diagnostic measures are derived to assess the influence of observations on the score statistics. Two examples that motivated the application of zero-inflated regression models are considered to illustrate the importance of sensitivity analysis of the zero-inflation tests.

Accidents, Occupational↗

PubMed2004

Modelling the distribution of ischaemic stroke-specific survival time using an EM-based mixture approach with random effects adjustment.

A two-component survival mixture model is proposed to analyse a set of ischaemic stroke-specific mortality data. The survival experience of stroke patients after index stroke may be described by a subpopulation of patients in the acute condition and another subpopulation of patients in the chronic phase. To adjust for the inherent correlation of observations due to random hospital effects, a mixture model of two survival functions with random effects is formulated. Assuming a Weibull hazard in both components, an EM algorithm is developed for the estimation of fixed effect parameters and variance components. A simulation study is conducted to assess the performance of the two-component survival mixture model estimators. Simulation results confirm the applicability of the proposed model in a small sample setting.

Age Factors↗

PubMed2004

Risk factors for ischaemic stroke recurrence after hospitalisation.

OBJECTIVE: To determine risk factors for ischaemic stroke recurrence among patients admitted to hospital for a first-ever occurrence of ischaemic stroke. DESIGN, SETTING AND PATIENTS: Retrospective study involving linked hospitalisation and death records. The cohort comprised 7816 people who were hospitalised for first-ever ischaemic stroke between July 1995 and December 1999 in Western Australia. Cox's proportional hazards model was used to identify risk factors for stroke recurrence. MAIN OUTCOME MEASURES: Time to first recurrence; cumulative recurrence risk; risk factors for recurrence. RESULTS: The median time to first stroke recurrence was 255 days. The cumulative probability of first recurrence was 5.1% (95% CI, 4.6%-5.7%) at 6 months, 8.4% (95% CI, 7.6%-9.1%) at 1 year and 19.8% (95% CI, 18.1%-21.4%) at 4 years. The risk of first recurrence was increased by advancing age (hazard ratio [HR], 1.03; 95% CI, 1.02-1.04), Aboriginality (HR, 1.50; 95% CI, 1.02-2.22), diabetes (HR, 1.27; 95% CI, 1.07-1.51), a history of cardiac conditions (HR, 1.18; 95% CI, 1.01-1.38), post-stroke urinary incontinence (HR, 1.27; 95% CI, 1.03-1.57) and transfer to another hospital on index admission (HR, 1.26; 95% CI, 1.08-1.46). Admission at first stroke occurrence to a hospital maintaining a stroke unit reduced the risk of recurrence (HR, 0.84; 95% CI, 0.72-0.99). CONCLUSION: The risk factors identified in our study have implications for planning secondary prevention strategies. In particular, Aboriginality and transfer to another hospital upon admission for first-ever ischaemic stroke were important risk factors. Research into the level of compliance and access to stroke treatment by Aboriginal patients to prevent further strokes is required.

Aged↗

PubMed2004

Protective effect of green tea against prostate cancer: a case-control study in southeast China.

To investigate whether green tea consumption has an etiological association with prostate cancer, a case-control study was conducted in Hangzhou, southeast China during 2001-2002. The cases were 130 incident patients with histologically confirmed adenocarcinoma of the prostate. The controls were 274 hospital inpatients without prostate cancer or any other malignant diseases, and matched to the age of cases. Information on duration, quantity and frequency of usual tea consumption, as well as the number of new batches brewed per day, were collected by face-to-face interview using a structured questionnaire. The risk of prostate cancer for tea consumption was assessed using multivariate logistic regression adjusting for age, locality, education, income, body mass index, physical activity, alcohol consumption, tobacco smoking, total fat intake, marital status, age at marriage, number of children, history of vasectomy and family history of prostate cancer. Among the cases, 55.4% were tea drinkers compared to 79.9% for the controls. Almost all the tea consumed was green tea. The prostate cancer risk declined with increasing frequency, duration and quantity of green tea consumption. The adjusted odds ratio (OR), relative to non-tea drinkers, were 0.28 (95% CI = 0.17-0.47) for tea drinking, 0.12 (95% CI = 0.06-0.26) for drinking tea over 40 years, 0.09 (95% CI = 0.04-0.21) for those consuming more than 1.5 kg of tea leaves yearly, and 0.27 (95% CI = 0.15-0.48) for those drinking more than 3 cups (1 litre) daily. The dose response relationships were also significant, suggesting that green tea is protective against prostate cancer.

Adenocarcinoma↗