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Biomedical subjects

W C Tan

Publications and source records attributed to W C Tan.

At least 19 recordsLinked to original sources
PubMed2006

Attitudes towards cancer survivors: a small survey.

INTRODUCTION: The National Cancer Survivors Day Foundation defines a cancer "survivor" as anyone living with a history of cancer--from the moment of diagnosis through the remainder of life. Little is known about the size and make-up of this population or about the medical care experience of and social implications for patients who have had a diagnosis of cancer in Singapore. An opportunistic survey was undertaken to understand how members of the public believe about this population. METHODS: A sample of the general public was undertaken during the "CancerVive" event in 2004. Questionnaires regarding employment as well as attitudes towards cancer and cancer survivorship were distributed. RESULTS: Members of the public held certain misconceptions about cancer survivors. They also have certain negative attitudes toward cancer survivors. Beliefs and attitudes about cancer are similar for cancer survivors and the general public. Although members of the public had positive attitudes towards working with cancer survivors, the majority felt that cancer survivors should not be given equal opportunities at work, by not employing cancer survivors if they were in the position to hire. CONCLUSION: Further research with larger and more representative samples needs to be undertaken to extend the understanding into cancer survivorship issues.

Attitude↗
PubMed2006

The clinical predictors of hypertension and sleepiness in an Asian population with sleep-disordered breathing.

INTRODUCTION: The objective of this study was to identify the clinical predictors for hypertension and sleepiness in an Asian population with sleep-disordered breathing (SDB). MATERIALS AND METHODS: This is a retrospective, consecutive case series of 228 patients with symptoms of SDB referred to a tertiary level sleep disorders unit. A full sleep history, body mass index (BMI), Epworth Sleepiness Score (ESS), apnoea-hypopnoea index (AHI) and lowest oxygen saturation were recorded. All patients had an in-hospital polysomnogram. AHI > or =5 defined SDB. ESS >8 defined sleepiness. RESULTS: A BMI of 25 had a positive and negative predictive value of 75% and 56%, respectively, for predicting AHI > or =5, area ROC (receiver operating curve) = 0.668. Patients with AHI >5 had 3 times the risk of developing hypertension compared to the population with AHI <5. Using stepwise multivariate analyses with constant, age, BMI and lowest oxygen desaturation were predictors for hypertension. Patients with AHI > or =5 were 1.88 times more likely to have ESS >8. After stepwise multivariate analyses, the subjective complaint of sleepiness and lowest oxygen saturation during sleep were predictors of ESS >8. CONCLUSION: The lowest oxygen saturation attained during sleep was the common factor for hypertension and sleepiness in our Asian SDB population. Mild obesity predisposes to AHI > or =5 in our population, the threshold at which the risk of hypertension is 3-fold compared with AHI <5. The subjective complaint of sleepiness predicted an ESS of >8.

Adult↗
PubMed2006

Dissemination and implementation of guidelines for the treatment of asthma.

Asthma remains a serious global health problem that affects people of all ages. Many asthma management guidelines, both national and international, are available, but they are seldom implemented. The implementation of guidelines remains a challenge worldwide, as barriers exist at several levels. These barriers are generic, such as poverty, inadequate resources and poor infrastructure, or specific, such as organisational, health care provider and patient factors. The barriers are, however, potentially correctable, and the goal of guideline implementation is to translate evidence-based asthma management recommendations into real-life practice to improve patient health. This state of the art article reviews the challenges and current status of and strategies for asthma dissemination and implementation globally, and highlights the specific strategies for such improvement in developing countries.

Asthma↗
PubMed2004

The burden and impact of COPD in Asia and Africa.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. The World Health Organization (WHO) estimated that COPD is currently the seventh leading cause of death and disability worldwide, but will rise to the fifth position by 2020. The estimated prevalence of COPD worldwide in 2001 was 1013/100,000 population; it was highest in the Western Pacific Region and lowest in Africa. The mortality from COPD followed the same pattern. The prevalence of smoking is slowly decreasing in the industrialised world and rising in developing countries, especially in Asia and Africa. Cigarette consumption per adult has also decreased in the Americas, remained the same in Europe but increased in all other regions, especially the Western Pacific. Indoor air pollution from combustion of biomass/traditional fuels and coal, previous tuberculous infection, outdoor air pollution and childhood respiratory infections are other important risk factors for COPD in developing countries. The rise in morbidity and mortality from COPD will be most dramatic in Asian and African countries over the next two decades, mostly due to progressive increase in the prevalence of smoking. As developing countries can ill afford the added economic burden of COPD and other smoking-related diseases, there is an urgent need for multi-dimensional actions in reducing the main risk factor of cigarette smoking.

Adult↗
PubMed2004

Management of chronic obstructive pulmonary disease in Asia and Africa.

This review examines whether the comprehensive programme recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), developed mostly by physicians in industrialised countries, can be applied in developing countries. In developing countries, there are several major limitations to the implementation of the programme. First, management of chronic obstructive pulmonary disease (COPD) patients is not a priority in competing for health care resources. Second, only major medical centres in developing countries have spirometers; the reliance on spirometric testing for diagnosis, staging and treatment options, as recommended by the GOLD guidelines, makes it almost impossible for the programme to be implemented. Third, in many Asian and African countries, regular monitoring is often restricted to patients with severe COPD who have frequent hospitalisations or clinic visits for exacerbations and complications. Fourth, the choice of therapy usually depends on the availability and cost of drugs. Finally, given the aetiological role of sequelae of lung infections, including tuberculosis, the appropriateness and safety of using intermittent courses of oral steroids during acute exacerbations and of long-term, high-dose inhaled corticosteroids for moderate to severe COPD in developing countries has not been evaluated. Developing countries in Asia and Africa may need to adapt the GOLD guidelines according to varying aetiology, local health care resources, socio-economic and cultural factors and development of health services. Prevention programmes, especially for tobacco control, are of paramount importance. National and international efforts must be directed towards controlling the tobacco epidemic in developing countries to reduce the burden of COPD and other tobacco-induced diseases.

Africa↗
PubMed2003

Survival among Chinese women with lung cancer in Singapore: a comparison by stage, histology and smoking status.

Lung cancer generally carries a poor prognosis and the determinants of survival have been of interest. However, survival estimates in Asian populations are scarce. This study describes survival rates and their determinants in Singapore Chinese women, a primarily non-smoking population. Three hundred and twenty-six Chinese women, diagnosed with primary lung carcinoma in three major hospitals in Singapore between April 1996 and December 1998, were followed up till 31 December 2000. The Kaplan-Meier method was used for survival analysis. Two hundred and eighty (85.7%) died from the disease during follow-up. The median survival time was 0.7 years and the three-year survival was 15.8%. These survival rates are similar to those of Western populations, and they provide a basis for examining trends over time. Age at diagnosis was an independent prognostic factor [adjusted hazard ratio (relative risk) 1.4, 95% confidence intervals (CI) 1.1-1.9 for women above 65 years relative to younger women]. Most (70.5%) tumours were stage III/IV at diagnosis. Three-year survival ranged from 72% among patients with stage I tumours to 7% for stage IV tumours. Overall, there was no survival difference among different histological types in all stages combined. When limited to stages I and II cancers, adenocarcinomas were associated with a better outcome relative to other histological subtypes combined (adjusted relative risk 0.4, 95% CI 0.1-1.0). Smoking was an independent risk factor (adjusted relative risk 1.3, 95% CI 1.0-1.8). Nevertheless, non-smokers comprised 57.4% of this series, highlighting the importance of increased awareness among health professionals and the public that lung cancer is not only a disease of smokers. The high proportion of late-stage tumours in this study and the impact of disease stage on outcome underline the importance of early detection in improving survival of lung cancer.

Adult↗
PubMed2003

Overview on SARS in Asia and the world.

Severe Acute Respiratory Syndrome (SARS) is the first major novel infectious disease to hit the international community in the 21st century. It originated in southern China in November 2002, reached Hong Kong in February 2003 and spread rapidly thereafter to 29 countries/regions on five continents. At the end of the epidemic, the global cumulative total was 8098 with 774 deaths. Seven Asian countries/regions were among the top ten on the list. Mainland China and Hong Kong, SAR, accounted for 87% of all cases and 84% of all deaths. Severe acute respiratory syndrome is caused by a novel coronavirus. It has alarmed the world with its infectivity and significant morbidity and mortality, its lack of a rapid, reliable diagnostic test and lack of effective specific treatment and vaccination. The adverse impact on travel and business around the world, particularly in Asia, has been enormous. Some lessons learnt from this epidemic included: (1) any outbreak of infectious disease can rapidly spread around the world by air travel; (2) early reporting of the outbreak to neighbouring countries/regions and the World Health Organization is essential to prevent international spread; and (3) infection control, tracing and quarantine of contacts are essential to control the epidemic. Many questions remain unanswered, including the origin and pathogenesis of the novel coronavirus, the natural history and the best specific treatment of the disease. The SARS-CoV has probably jumped from an animal host to humans. There is an urgent need to evaluate the human-animal habitat in southern China and to remove animal reservoirs if found.

China↗
PubMed2003

Changing trends in indications for caesarean sections in a tertiary hospital.

OBJECTIVES: To study the caesarean section rate and the trends in indications for caesarean delivery at the Singapore General Hospital (SGH) during two study periods of 6 months each. MATERIALS AND METHODS: The percentages of caesarean sections attributable to specific indications were computed for the first 6 months of 1998 and the last 6 months of 2001. Subgroup analysis of "less common indications" was performed. RESULTS: In the first half of 1998, 170 caesarean sections were performed giving a rate of 16.77%. 54.12% of women were multiparous. The main indication for caesarean section was dystocia (4.24% of deliveries). Two hundred and sixty caesarean sections were performed in the later half of 2001 giving a caesarean section rate of 25.10%. 53.46% of women were multiparous. The main indication for caesarean section was dystocia (5.41% of deliveries). Increase in caesarean section rate in 2001 was attributed to statistically significant increase in caesarean section for previous caesarean section and placenta previa major. Other changes in practice included shorter operating time which may be related to decision not to perform peritoneal closure. CONCLUSION: Studying indications for caesarean section are useful for hospitals, clinicians and researchers in determining strategies to lower primary and repeat caesarean section rate.

Adult↗
PubMed2003

Audit of 'crash' emergency caesarean sections due to cord prolapse in terms of response time and perinatal outcome.

OBJECTIVE: The objective was to audit 'crash' emergency caesarean sections (CS) with respect to response time (the diagnosis to delivery interval [DDI]) and perinatal outcome. MATERIALS AND METHODS: The computerised database at the Singapore General Hospital (SGH) delivery suite was used to identify all cases of 'crash' emergency CS activated for the diagnosis of cord prolapse from 1992 to 2002. Patients' case notes and neonatal charts were reviewed and the following variables were evaluated: parity, gestational age at the time of delivery and the DDI. Neonatal outcome was measured by Apgar scores at 1 and 5 minutes, cord pH and admission to the neonatal intensive care unit (NICU). RESULTS: A total of 34 cases of umbilical cord prolapse were identified from 29,867 deliveries, giving an incidence of 0.11% (1 in 900). The median gestational age was 38.5 weeks (range, 25 to 41 weeks). The median time from diagnosis to delivery was 20 minutes (range, 10 to 40 minutes). Seventy-six percent (19/30) were delivered within 30 minutes. The time of diagnosis was not recorded for 5 cases. Sixty-three percent of neonates had an Apgar score < or = 7 at 1 minute of life, increasing to 97% at 5 minutes. There were 3 NICU admissions for reasons of prematurity. There was no perinatal mortality. Cord pH was not performed for 47% of (14/30) neonates. Among the remaining 16 neonates, an umbilical cord pH of < or = 7.20 was found in 62% (10/16). There was poor correlation between the DDI and umbilical cord pH. CONCLUSION: Three-quarters of our 'crash' emergency CS for cord prolapse were performed within 30 minutes with a good perinatal outcome. However, we have identified areas for improvement to optimise further the operational efficiency of 'crash' emergency CS.

Adolescent↗
PubMed2002

Role of antibiotic prophylaxis for wound infection in percutaneous endoscopic gastrostomy (PEG): result of a prospective double-blind randomized trial.

A randomized, double-blind, controlled trial was carried out to determine the value of antibiotic prophylaxis in the prevention of wound infection in percutaneous endoscopic gastrostomy (PEG) procedures. The wound was evaluated using ASEPSIS method and categorized as disturbance of healing, minor or major wound infection on the 7th day and the 28th day. The rate of infection including major wound infection was lower in the prophylaxis group of patients at both seven and 28 days.

Adult↗
PubMed2001

Cytokines involved in the systemic inflammatory response induced by exposure to particulate matter air pollutants (PM(10)).

Elevated levels of ambient particulate matter (PM(10)) have been associated with increased cardiopulmonary morbidity and mortality. We previously showed that the deposition of particles in the lung induces a systemic inflammatory response that includes stimulation of the bone marrow. This marrow response is related to mediators released by alveolar macrophages (AM) and in this study we measured cytokines produced by human AM exposed to ambient particles of different composition and size. Identified cytokines were also measured in the circulation of healthy young subjects exposed to air pollutants during the 1997 Southeast Asian forest fires. Human AM were incubated with particle suspensions of residual oil fly ash (ROFA), ambient urban particles (EHC 93), inert carbon particles, and latex particles of different sizes (0.1, 1, and 10 microm) and concentrations for 24 h. Tumor necrosis factor-alpha (TNF-alpha) increases in a dose-dependent manner when AM were exposed to EHC 93 particles (p < 0.02). The TNF response of AM exposed to different sizes of latex particles was similar. The latex (158 +/- 31%), inert carbon (179 +/- 32%), and ROFA (216 +/- 34%) particles all show a similar maximum TNF response (percent change from baseline) whereas EHC 93 (1,020 +/- 212%, p < 0.05) showed a greater maximum response that was similar to lipopolysaccharide (LPS) 1 microg/ml (812 +/- 320%). Macrophages incubated with an optimal dose of EHC 93 particles (0.1 mg/ml) also produce a broad spectrum of other proinflammatory cytokines, particularly interleukin (IL)-6 (p < 0.01), IL-1 beta (p < 0.05), macrophage inflammatory protein-1 alpha (MIP-1 alpha) (p < 0.05), and granulocyte macrophage colony-stimulating factor (GM-CSF) (p < 0.01) with no difference in concentrations of the anti-inflammatory cytokine IL-10 (p = NS). Circulating levels of IL-1 beta, IL-6, and GM-CSF were elevated in subjects exposed to high levels of PM(10) during an episode of acute air pollution. These results show that a range of different particles stimulate AM to produce proinflammatory cytokines and these cytokines are also present in the blood of subjects during an episode of acute atmospheric air pollution. We postulate that these cytokines induced a systemic response that has an important role in the pathogenesis of the cardiopulmonary adverse health effects associated with atmospheric pollution.

Aged↗
PubMed2001

Comparison of different methods of total RNA extraction for viral detection in sputum.

Examination of sputum specimens can be used for monitoring airway inflammation by means of immunological and molecular techniques. RNA extraction is essential for measurement of cytokine gene expression and for detection of many viral pathogens in sputum. In this study, three RNA extraction methods used commonly (acid guanidinium thiocyanate-phenol-chloroform extraction, Trizol and RNeasy Mini kit) were compared on the sputum of 14 patients who had chronic obstructive pulmonary disease. The effect of dithiothreitol pre-treatment on sputum RNA extraction was also investigated. The yield and purity of total RNA were determined by spectrophotometry. Reverse transcription-polymerase chain reaction (RT-PCR) results of the house keeping gene (glyceraldehyde-3-phosphate dehydrogenase) and RNA sequences specific to common respiratory viruses were compared. The results showed that (1) total RNA extracted with Trizol had highest yield and purity among the three RNA extraction methods; (2) there was no significant difference among the three RNA extraction methods on the house keeping gene and viral detection by RT-PCR; (3) dithiothreitol pre-treatment did not improve either the purity of total RNA, or RT-PCR signal. Moreover, dithiothreitol treatment reduced significantly the yield of total RNA. The results of the study indicate that the Trizol method appears to be superior for total RNA extraction from sputum, and dithiothreitol pre-treatment does not increase the efficiency of RNA extraction and RNA detection in sputum specimens.

Dithiothreitol↗
PubMed2001

Design and analytic considerations in determining the cost-effectiveness of early intervention in asthma from a multinational clinical trial.

Demand for economic and outcomes data in support of drug formulary listing in private and government-sponsored health programs has led to fundamental changes in drug development. In part as a response to these pressures, the pharmaceutical industry has begun to include economic and quality-of-life endpoints in clinical trials with the hope of providing information to answer health policy questions on the economic value of its products. Here, the design and health economic techniques that will be used to analyze the START (inhaled Steroid Treatment As Regular Therapy in early asthma) study-a multinational (31 countries), randomized, placebo-controlled trial of 7240 patients with mild asthma over 3 years-will be presented. START compares the effect of once-daily administration of an inhaled glucocorticosteroid (Pulmicort Turbuhaler to conventional therapy in the management of newly diagnosed asthma, for which the use of this therapy is currently not the standard. The START study will examine both clinical effectiveness (measured as symptom-free days) and asthma-related costs for both treatment arms, aggregated for all patients across all countries. We believe that presenting the analytical plan prior to disseminating the results is an important way of increasing the credibility of economic evaluations. However, using clinical trials for collecting economic data poses several challenges, and the methods for conducting such evaluations are being developed. This paper will present and discuss several methodological options and the current state of the art for conducting economic evaluations alongside multinational clinical trials.

Administration, Inhalation↗
PubMed2001

The inhaled Steroid Treatment as Regular Therapy in early asthma (START) study: rationale and design.

Although the beneficial effects of treatment with inhaled steroids in asthma are widely accepted, the role of early intervention in patients with mild asthma remains unsettled. Conventional efficacy trials are often of short duration and involve highly selected patient populations that exclude many patients typical of those encountered in routine clinical practice. Hence, a large "real-world" effectiveness study is needed to evaluate the benefits of early intervention with inhaled steroids in patients with mild, persistent asthma. In the START (inhaled Steroid Treatment As Regular Therapy in early asthma) study, patients ages 6-60 years, from 31 countries and districts worldwide with mild persistent asthma, have been randomized to once-daily treatment with budesonide, 200 microg (for patients < 11 years) or 400 microg (for patients > or = 11 years), or placebo via Turbuhaler for 3 years. The double-blind treatment period will be followed by a 2-year period of open budesonide treatment. Throughout the study, other asthma medication including glucocorticosteroids can be given as judged appropriate by the investigator. Lung function will be measured by spirometry using standardized techniques at 3-month intervals throughout the study, and bronchodilator reversibility will be measured annually. The primary outcome measures are the time to the first severe asthma-related event during the first 3 years of the study and the change in postbronchodilator forced expiratory volume in 1 second (FEV(1)) from baseline during the entire 5-year study period. These measures have been chosen to reflect the progression of mild asthma toward more severe asthma and the extent of irreversible airflow limitation, which should reflect the degree of airway remodeling.

Acute Disease↗
PubMed2001

Clinical management of PCOS.

The polycystic ovary syndrome (PCOS) is a heterogeneous condition with genetic predisposition. It is characterized by a myriad of symptoms including oligomenorrhea or amenorrhea, anovulation or infertility, hirsutism or acne. Insulin resistance appears to be an important factor in PCOS though the lack of an etiology has led to symptom oriented therapy which includes lifestyle modification, the use of cyclical progestagens and antiandrogens. Ovulation induction by drug therapy and ovarian drilling aims to treat subfertility in women with PCOS. Therapeutic approaches to PCOS remain an ongoing source of debate. Insulin sensitizing agents may bring new hope in therapy. Future research is aimed at shedding light on the pathophysiology so as to optimize treatment of women with PCOS.

Contraceptives, Oral↗
PubMed2001

Cytochrome P4501A2 (CYP1A2) activity and lung cancer risk: a preliminary study among Chinese women in Singapore.

There is increasing evidence for the role of heterocyclic and other arylamines in carcinogenesis, including lung carcinogenesis. Chinese women have a high rate of lung cancer despite a low smoking prevalence, and studies in this population may provide useful information on risk factors other than smoking. Hepatic CYP1A2 and NAT2 are involved in the metabolism of carcinogenic arylamines, and NAT2 also catalyzes the detoxification pathway for these compounds. In this study, we examined the effect of CYP1A2 activity using a urinary caffeine metabolic ratio assay for 54 Chinese women with newly diagnosed lung cancer (including 28 adenocarcinomas) and 174 hospital controls. Among them, NAT2 genotype was available for 47 cases and 98 controls. There was no effect of CYP1A2 activity on overall risk of lung cancer in the study population [odds ratio (OR) 0.8, 95% confidence interval (CI) 0.4-1.6, adjusted for age at diagnosis, smoking and cruciferous vegetable intake]. For adenocarcinomas, the OR was 1.5, 95% CI 0.6-3.4. After further adjustment for NAT2 acetylator genotype, the OR for adenocarcinoma was 1.8 (95% CI 0.7-4.8). When the combined NAT2/CYP1A2 status was examined, women with slow NAT2 and rapid CYP1A2 activity were at highest risk (adjusted OR 6.9, 95% CI 1.3-37.6) relative to women with rapid NAT2 and slow CYP1A2 activity, for lung adenocarcinoma. While larger studies are needed to confirm or refute these results, they are consistent with a role for heterocyclic arylamines in lung carcinogenesis in this primarily non-smoking population.

Adenocarcinoma↗
PubMed2001

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women.

BACKGROUND: Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women. METHODS: Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks. RESULTS: Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=-0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2 (r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=-0.512; p=0.051) and respiratory symptom severity score (r= -0.567; p=0.043), probably due to the masking effects of bronchodilator treatment. CONCLUSIONS: Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Adult↗