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K S Chia

Publications and source records attributed to K S Chia.

At least 19 recordsLinked to original sources
PubMed2024

Long-term exposure to particulate matter and all-cause and cause-specific mortality in an analysis of multiple Asian cohorts.

BACKGROUND: Exposure to ambient air pollution is associated with a significant number of deaths. Much of the evidence associating air pollution with adverse effects is from North American and Europe, partially due to incomplete data in other regions limiting location specific examinations. The aim of the current paper is to leverage satellite derived air quality data to examine the relationship between ambient particulate matter and all-cause and cause-specific mortality in Asia. METHODS: Six cohorts from the Asia Cohort Consortium provided residential information for participants, recruited between 1991 and 2008, across six countries (Bangladesh, India, Iran, Japan, South Korea, and Taiwan). Ambient particulate material (PM2·5) levels for the year of enrolment (or 1998 if enrolled earlier) were assigned utilizing satellite and sensor-based maps. Cox proportional models were used to examine the association between ambient air pollution and all-cause and cause-specific mortality (all cancer, lung cancer, cardiovascular and lung disease). Models were additionally adjusted for urbanicity (representing urban and built characteristics) and stratified by smoking status in secondary analyses. Country-specific findings were pooled via random-effects meta-analysis. FINDINGS: More than 300,000 participants across six cohorts were included, representing more than 4-million-person years. A positive relationship was observed between a 5 µg/m (Dockery et al., 1993) increase in PM2·5 and cardiovascular mortality (HR: 1·06, 95 % CI: 0.99, 1·13). The additional adjustment for urbanicity resulted in increased associations between PM2.5 and mortality outcomes, including all-cause mortality (1·04, 95 % CI: 0·97, 1·11). Results were generally similar regardless of whether one was a current, never, or ex-smoker. INTERPRETATION: Using satellite and remote sensing technology we showed that associations between PM2.5 and all-cause and cause-specific Hazard Ratios estimated are similar to those reported for U.S. and European cohorts. FUNDING: This project was supported by the Health Effects Institute. Grant number #4963-RFA/18-5. Specific funding support for individual cohorts is described in the Acknowledgements.

Humans↗
PubMed2006

Ethnicity modifies the association between diabetes mellitus and ischaemic heart disease in Chinese, Malays and Asian Indians living in Singapore.

AIMS/HYPOTHESIS: The aim of the study was to determine whether the risk of ischaemic heart disease (IHD) associated with diabetes mellitus differs between ethnic groups. METHODS: Registry linkage was used to identify IHD events in 5707 Chinese, Malay and Asian Indian participants from three cross-sectional studies conducted in Singapore between the years 1984 and 1995. The study provided a median of 10.2 years of follow-up with 240 IHD events experienced. We assessed the interaction between diabetes mellitus and ethnicity in relation to the risk of IHD events using Cox proportional hazards regression. RESULTS: Diabetes mellitus was more common in Asian Indians. Furthermore, diabetes mellitus was associated with a greater risk of IHD in Asian Indians. The hazard ratio when comparing diabetes mellitus with non-diabetes mellitus was 6.41 (95% CI 5.77-7.12) in Asian Indians and 3.07 (95% CI 1.86-5.06) in Chinese (p = 0.009 for interaction). Differences in the levels of established IHD risk factors among diabetics from the three ethnic groups did not appear to explain the differences in IHD risk. CONCLUSIONS/INTERPRETATION: Asian Indians are more susceptible to the development of diabetes mellitus than Chinese and Malays. When Asian Indians do develop diabetes mellitus, the risk of IHD is higher than for Chinese and Malays. Consequently, the prevention of diabetes mellitus amongst this ethnic group is particularly important for the prevention of IHD in Asia, especially given the size of the population at risk. Elucidation of the reasons for these ethnic differences may help us understand the pathogenesis of IHD in those with diabetes mellitus.

Adult↗
PubMed2005

Angiotensin-I converting enzyme insertion/deletion polymorphism and its association with diabetic nephropathy: a meta-analysis of studies reported between 1994 and 2004 and comprising 14,727 subjects.

AIMS/HYPOTHESIS: The ACE insertion/deletion polymorphism has been examined for association with diabetic nephropathy over the past decade with conflicting results. To clarify this situation, we conducted a comprehensive meta-analysis encompassing all relevant studies that were published between 1994 and 2004 and investigated this potential genetic association. METHODS: A total of 14,727 subjects from 47 studies was included in this meta-analysis. Cases (n=8,663) were type 1 or 2 diabetic subjects with incipient (microalbuminuria) or advanced diabetic nephropathy (proteinuria, chronic renal failure, end-stage renal disease). Control subjects (n=6,064) were predominantly normoalbuminuric. RESULTS: No obvious publication bias was detected. Using a minimal-case definition based on incipient diabetic nephropathy, subjects with the II genotype had a 22% lower risk of diabetic nephropathy than carriers of the D allele (pooled odds ratio [OR]=0.78, 95% CI=0.69-0.88). While there was a reduced risk of diabetic nephropathy associated with the II genotype among Caucasians with either type 1 or type 2 diabetes, the association was most marked among type 2 diabetic Asians (Chinese, Japanese, Koreans) (OR=0.65, 95% CI=0. 51-0.83). This OR is significantly different from the OR of 0.90 (95% CI= 0.78-1.04) that was obtained for type 2 diabetic Caucasians (p=0.019). Using a stricter case definition based on advanced diabetic nephropathy, a comparable risk reduction of 24-32% was observed among the three subgroups, although statistical significance was reached only among Asians. CONCLUSIONS/INTERPRETATION: The results of our meta-analysis support a genetic association of the ACE Ins/Del polymorphism with diabetic nephropathy. These findings may have implications for the management of diabetic nephropathy using ACE inhibitors especially among type 2 diabetic Asians.

Case-Control Studies↗
PubMed2005

Role of urinary screening programmes in children in the prevention of chronic kidney disease.

INTRODUCTION: This article reviews published literature on the usefulness of population-based urinary screening in the Asian paediatric population. METHODS: Articles were found in the Medline database using the key words "paediatrics", "urine screening", "proteinuria", "haematuria" and "population". The Asian countries which had carried out population-based urinary screening of the paediatric population included Taiwan, Japan and Korea. One study was found on urinary screening in a select population in Malaysia. Preliminary results of the urinary screening of school children in Singapore are presented and compared with the results found in the above-mentioned countries. RESULTS: Overall, the proportion of children found to have urinary abnormalities ranged from less than 0.1% of the population screened to almost 50% of a select cohort referred from the screening programmes for the evaluation of urinary abnormalities. In the pilot Singapore school screening programme, the prevalence of clinically significant proteinuria was 1.25 per 1000 children screened. Multivariate analysis showed that low body weight was associated with a 1.8-fold greater risk for proteinuria. The major cause of haematuria and proteinuria in those studies where renal biopsies were performed was glomerulonephritis. The Taiwanese experience also showed a reduction in the incidence of end-stage renal failure diagnosed in children after the onset of urine screening. CONCLUSION: These studies showed that urinary screening programmes in school children allow the early detection of disease. The cost-benefit ratio for specific populations should be determined before the implementation of such programmes.

Asia↗
PubMed2004

The lipoprotein lipase S447X polymorphism and plasma lipids: interactions with APOE polymorphisms, smoking, and alcohol consumption.

We studied 4,058 subjects from a representative sample of the Singapore population 1) to determine the association between the S447X polymorphism at the LPL locus and serum lipid concentration in Chinese, Malays, and Asian Indians living in Singapore and 2) to explore any interactions with apolipoprotein E (APOE) genotype, exercise, obesity, cigarette smoking, and alcohol intake. Information on obesity, lifestyle factors (including smoking, alcohol consumption, and exercise frequency), glucose tolerance, and fasting lipids was obtained. Male and female carriers of the X447 allele had lower serum triglyceride concentrations and higher HDL cholesterol (HDL-C) concentrations. The association between the X447 allele and serum HDL-C concentration was modulated by APOE genotype in males and cigarette smoking and alcohol intake in females. The effect of the X447 allele was greatest in men who carried the E4 allele and women who smoked or consumed alcohol. The X447 allele at the LPL locus is common and associated with a less atherogenic lipid profile in Asian populations. Interactions with APOE genotype, cigarette smoking, and alcohol intake reinforce the importance of examining genetic associations, such as this one, in the context of the population of interest.

Adult↗
PubMed2004

Willingness to donate blood samples for genetic research: a survey from a community in Singapore.

Studies on the public's willingness to donate blood specimens for genetic research are few and are conducted mainly among Western countries. Little is known about the Asian community's willingness to participate in genetic research. A community-based survey was conducted on 548 adult Singaporeans to examine their willingness to donate blood samples for genetic research and its associated factors. The response rate was 70.3%. About 49.3% (95% CI, 45.1-53.5%) were willing to donate blood for genetic research. In the multivariable Cox regression analysis, willingness was significantly associated with belief in the benefits of genetic research; intention to participate in government studies; having no fear of pain, blood, injections, and needles; and non-concern about the loss of confidentiality. Reasons against donating blood were fear of pain, blood, injections, and needles (38.1%); no self-benefits (24.8%); fear of finding out about having a disease (22.3%); fear of discrimination (18.7%); and concerns about weakness (15.1%) and weight gain (9.4%). Public education programs to promote participation in genetic research should stress its benefits and address people's fears and concerns.

Adult↗
PubMed2004

Ethnic variations in female vulnerability after an acute coronary event.

OBJECTIVE: To determine the ethnic variation of short and long term female vulnerability after an acute coronary event in a population of Chinese, Indians, and Malays. DESIGN: Population based registry. PATIENTS: Residents of Singapore between the ages of 20-64 years with coronary events. Case identification and classification procedures were modified from the MONICA (monitoring trends and determinants in cardiovascular disease) project. MAIN OUTCOME MEASURES: Adjusted 28 day case fatality and long term mortality. RESULTS: From 1991 to 1999, there were 16 320 acute coronary events, including 3497 women. Age adjusted 28 day case fatality was greater in women (51.5% v 38.6%, p < 0.001), with a larger sex difference evident among younger Malay patients. This inequality between the sexes was observed in both the pre-hospitalisation and post-admission periods. Among hospitalised patients, women were older, were less likely to have suffered from a previous Q wave or anterior wall myocardial infarction, and had lower peak creatine kinase concentrations. Case fatality was higher among women, with adjusted hazard ratios of 1.64 (95% confidence interval (CI) 1.43 to 1.88) and 1.50 (95% CI 1.37 to 1.64) for 28 day and mean four year follow up periods. There were significant interactions of sex and age with ethnic group (p = 0.017). The adjusted hazards for mortality among Chinese, Indian, and Malay women versus men were 1.30, 1.71, and 1.96, respectively. The excess mortality among women diminished with age. CONCLUSION: In this multiethnic population, both pre-hospitalisation and post-admission case fatality rates were substantially higher among women. The sex discrepancy in long term mortality was greatest among Malays and in the younger age groups.

Acute Disease↗
PubMed2004

Ethnic differences among Chinese, Malay and Indian patients with type 2 diabetes mellitus in Singapore.

INTRODUCTION: Ethnic differences exist in patients with diabetes mellitus. Not much is known about such differences in Asian populations. The aim of the study was to determine ethnic differences among Chinese, Malay and Indian patients with type 2 diabetes mellitus in Singapore. METHODS: The study design was cross-sectional, involving 967 patients who were attending follow-up care for type 2 diabetes mellitus at a primary care clinic. Data collection was by patient interview, examination, and from case records. Blood and urine samples were collected for analysis of indicators of diabetic control and albuminuria. RESULTS: Malays had the highest mean body mass index (BMI) after controlling for age, gender, duration of diabetes and exercise status. Adjusted mean BMI for Malays was 27.4kg per square metres, Indians 25.7kg per square metres, Chinese 24.9kg per square metres, with the p value being less than 0.01. HbA1c levels were highest among Indians after controlling for age, duration of diabetes, body mass index and treatment. Adjusted mean HbA1c for Indians was 8.3 percent, Malays 8.0 percent, and Chinese 7.7 percent, with the p value being less than 0.01. Compared with Chinese, Indians were more likely to have a positive family history of diabetes (prevalence rate ratio (PRR) of 1.3, 95 percent confidence interval (CI) of 1.0 to 1.7), but were less likely to have associated hypertension (PRR of 0.7, 95 percent CI of 0.5 to 1.0) and microalbuminuria and macroalbuminuria (PRR of 0.6, 95 percent CI of 0.4 to 1.0). CONCLUSION: Ethnic differences exist with regard to BMI, diabetic control as reflected by HbA1c levels, family history of diabetes, presence of associated hypertension, and severity of albuminuria. Indians, while having poorer control of diabetes, are less prone to hypertension and renal complications than Chinese.

Aged↗
PubMed2004

Twin births in Singapore: a population-based study using the National Birth Registry.

INTRODUCTION: Twin studies are a most effective method to analyse gene and environment interactions. Using data from the Singapore National Registry of Births and Deaths (SNRBD), this paper describes the number of twin and multiple births among different ethnic populations in Singapore. MATERIALS AND METHODS: All births recorded in the SNRBD from 1 January 1986 to 31 December 2001 were analysed. Outcomes measured were twin and triple birth rates (per 1000 maternities) of the 3 main ethnic groups in Singapore (Chinese, Malays and Asian Indians). Further outcomes were calculated using Weinberg's differential rule to estimate the number of monozygotic and dizygotic twins. RESULTS: Overall twin birth rates have steadily increased across all ethnic groups (7 to 9/1000). The largest increase in multiple births among the ethnic groups were twins born to Asian Indian fathers (6.9 to 9.9/1000) and Malay mothers (5.9 to 9.8/1000). A significant difference in birth rates between the ethnic groups was found during the years 1994 to 1997, where Chinese parents had the lowest multiple birth rates and Asian Indians the highest. Estimation and ratios of monozygotic and dizygotic twin births differed among the ethnic groups: Asian Indians had the highest ratios, followed by the Chinese and, lastly, the Malays. CONCLUSION: The SNRBD has provided an overview of multiple births in Singapore, although the establishment of a national twin register would enable more detailed analysis of genetic and environmental effects in multiple births.

Asian People↗
PubMed2003

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population.

BACKGROUND: Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians. METHODS: This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus. RESULTS: Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays. CONCLUSION: Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

Alcohol Drinking↗
PubMed2003

Basal cell carcinoma, squamous cell carcinoma and melanoma of the skin: analysis of the Singapore Cancer Registry data 1968-97.

BACKGROUND: There has been an alarming recent increase in skin cancer incidence among fair-skinned populations. Information from Asian populations is less readily available. OBJECTIVES: This study examines time trends and ethnic differences of skin cancers among Asians in Singapore. METHODS: Data from 1968 to 1997 was obtained from the Singapore Cancer Registry, a population-based registry. Age-standardized incidence rates (ASRs) and age-adjusted average annual percentage change, using the Poisson regression model, were calculated. RESULTS: A total of 2650 basal cell carcinomas (BCCs), 1407 squamous cell carcinomas (SCCs) and 281 melanomas were reported. There was an overall increase of skin cancer from 6.0 per 100000 person years (1968-72) to 8.9 per 100000 person years (1993-97). BCC incidence increased 3% annually, melanoma remained constant, and SCC decreased 0.9% annually. BCC ASRs were highest among Chinese, then Malays and Indians. A similar pattern was noted for SCC and melanomas. CONCLUSIONS: The incidence rates of skin cancer increased in Singapore during the period 1968-97. Fairer-skinned Chinese had a higher incidence of skin cancer.

Adult↗
PubMed2002

Angular regression and the detection of the seasonal onset of disease.

BACKGROUND: In examining the seasonality of onset of a disease over the year, investigators attempt to identify the peak of onset, and its magnitude. A second objective is to see if the day in which the disease manifests itself is related to subject-specific characteristics or environmental factors. METHOD: This paper describes appropriate statistical methodology for the situation where seasonality can be summarised by either a single peak or several peaks, possibly determined by patient characteristics or external influences. The circular, rather than linear, nature of the day of onset of a disease (irrespective of year) requires angular regression techniques to assess these relations, and the von Mises distribution replaces the normal distribution in this context. RESULTS: The methods outlined are illustrated by a national study of those experiencing an attack of acute primary angle-closure glaucoma in Singapore. CONCLUSIONS: We recommend re-analyses of already published work on seasonality of disease using this angular methodology. We anticipate that this may provide both useful further insight into aspects of aetiology and case studies for the methods themselves.

Acute Disease↗
PubMed2002

Cancer incidence in Singapore, 1998 to 1999.

The age-standardised incidence rates for all cancers for 1998-1999 were 235.0 per 100,000 in males and 199.8 per 100,000 in females. The corresponding rates for 1993-1997 were 233.1 per 100,000 in males and 198.1 per 100,000 in females. The greatest difference was for breast cancer in females with age-standardised incidence rates increasing from 46.1 to 53.1 cases per 100,000 persons per year between these time periods. There also appears to be a shift of the peak age-specific incidence for breast cancer from premenopausal to postmenopausal years over this period. This suggests that our breast cancer incidence pattern is rapidly becoming more similar to populations in the West.

Adult↗
PubMed2001

Population-based cancer survival in Singapore, 1968 to 1992: an overview.

The Singapore Cancer Registry has provided comprehensive population-based incidence data since 1968. This paper describes the population-based survival analysis of the registry data. All invasive primary cancers diagnosed from January 1, 1968 to December 31, 1992 were passively followed up until December 31, 1997. Only 5.8% were lost to follow-up. Cumulative and observed survival rates were calculated using Hakulinen's method. Overall 5-year relative survival rates have increased dramatically over the 25-year period in both genders. Significant increases are seen with nasopharynx, stomach and colo-rectum cancers, non-Hodgkin's lymphoma, leukemias and cancers of the testis, cervix, ovaries and breast. When compared with the Surveillance, Epidemiology and End Results (SEER) rates in the United States, the 5-year relative survival rates in Singapore are generally lower. However, the rate of change between the two countries is fairly similar. On the average, the rates are 10 to 15 years behind the SEER rates and 5 to 10 years behind Finland, Switzerland and Japan, but they are close to the UK rates. The age-standardized 5-year survival rate for Singapore is higher for most sites compared with other developing countries like Qidong (China), Madras (India), Bombay (India) and Chiang Mai (Thailand). The 25-year trend in cancer survival in Singapore showed two extreme groups: those showing no change and those showing significant improvements. Reducing the incidence of cancers belonging to the first group remains the only viable mode of cancer control. For cancers in the second group, improvement in survival is due to a combination of successful early detection measures and effective treatment services in Singapore.

Age Factors↗
PubMed2001

Risk factors and incident coronary heart disease in Chinese, Malay and Asian Indian males: the Singapore Cardiovascular Cohort Study.

OBJECTIVE: This prospective study in Singapore investigated the relationships of established coronary risk factors with incident coronary heart disease (CHD) for Chinese, Malay, and Asian Indian males. SUBJECTS: A cohort (consisting of 2879 males without diagnosed CHD) derived from three previous cross-sectional surveys. METHODS: Individual baseline data were linked to registry databases to obtain the first event of CHD. Hazard ratios (HR) or relative risks for risk factors were calculated using Cox's proportional hazards model with adjustment for age and ethnic group and adjustment for age, ethnic group and all other risk factors (overall adjusted). RESULTS: There were 24,986 person-years of follow-up. The overall adjusted HR with 95% CI are presented here. Asian Indians were at greatest risk of CHD, compared to Chinese (3.0; 2.0-4.8) and Malays (3.4; 1.9-3.3). Individuals with hypertension (2.4; 1.6-2.7) or diabetes (1.7; 1.1-2.7) showed a higher risk of CHD. High low density lipoprotein cholesterol (LDL-C) (1.5; 1.0-2.1), high fasting triglyceride (1.5; 0.9-2.6) and low high density lipoprotein cholesterol (HDL-C) (1.3; 0.9-2.0) showed a lesser but still increased risk. Alcohol intake was protective with non-drinkers having an increased risk of CHD (1.8; 1.0-3.3). Obesity (body mass index > or =30) showed an increased risk (1.8; 0.6-5.4). An increased risk of CHD was found in cigarette smokers of > or =20 pack years (1.5; 0.9-2.5) but not with lesser amounts. CONCLUSIONS: The increased susceptibility of Asian Indian males to CHD has been confirmed in a longitudinal study. All of the examined established risk factors for CHD were found to play important but varying roles in the ethnic groups in Singapore.

Adult↗
PubMed2001

Does education explain ethnic differences in myopia prevalence? A population-based study of young adult males in Singapore.

PURPOSE: To study interethnic variation in myopia prevalence and severity in young adult males in Singapore and to determine whether these variations are related to differences in education level. METHODS: A population-based survey of refractive errors in a cohort of 15,095 military conscripts between July 1996 and June 1997 using noncycloplegic autorefraction and a standard questionnaire. Prevalence rates of myopia (<-0.5 D) and severe myopia (<-6.0 D) were determined for Chinese, Malay, and Indian men; prevalence rate ratios were compared after adjusting for education level. RESULTS: Singapore has one of the highest prevalences of myopia (79.3%) and severe myopia (13.1%), with Chinese having higher rates (82.2%, 95% confidence interval 81.5, 82.9) compared with Indians (68.7%, 95% confidence interval 65.1, 67.1) and Malays (65.0%, 95% confidence interval 62.9, 67.1). Education was strongly associated with prevalence and severity of myopia. However, significant interethnic variation persisted after adjusting for education. CONCLUSIONS: There is a high prevalence of myopia in Singapore. Although prevalence and severity of myopia were strongly associated with education, interethnic variation observed was not fully explained by differences in education level.

Adolescent↗