The lipoprotein lipase S447X polymorphism and plasma lipids

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.

Ethnic differences in utilization of invasive cardiac procedures and in long-term survival following acute myocardial infarction

BACKGROUND

Ethnic differences in coronary mortality have been documented, and South Asians from the Indian subcontinent are particularly vulnerable.

HYPOTHESIS

This study sought to determine whether there was a difference in the utilization of invasive cardiac procedures and long-term mortality in survivors of myocardial infarction (MI) among Chinese, Malays, and South Asians in Singapore.

METHODS

All MI events in the country were identified and defined by the Singapore Myocardial Infarction Register, which uses modified procedures of the World Health Organization MONICA Project. Information on utilization of coronary angiography, coronary angioplasty, coronary artery bypass graft, and survival was obtained by data linkage with national billing and death registries. Hazard ratios (HR) were calculated using the Cox proportional hazards model with adjustment for baseline characteristics.

RESULTS

From 1991 to 1999, there were 10,294 patients who survived > or = 3 days of MI. Of these, 40.6% underwent coronary angiography and 16.5% a revascularization procedure < or = 28 days. Malays received substantially less angiography (34.0%) and revascularization (11.4%) than Chinese (41.9%, 17.9%) and South Asians (40.0%, 16.3%). The ethnic disparity increased during the 1990s, particularly in the performance of coronary angiography (p = 0.038). While fatality declined during the study period for Chinese and South Asians, the rate remained stable for Malays. After a median follow-up period of 4.1 years, survival was lowest among Malays (adjusted HR, 1.28; 95% confidence interval, 1.15-1.42, compared with Chinese).

CONCLUSION

Ethnic inequalities in invasive cardiac procedures exist in Singapore and were exacerbated in the 1990s. Inequalities in medical care may contribute to the poorer longterm survival among Malays.

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.

Scrutiny of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) locus reveals conserved haplotype block structure not associated with diabetic nephropathy

Glutamine-fructose-6-phosphate transaminase 1 (GFAT) is the rate-limiting enzyme of the hexosamine pathway that has been implicated in the pathogenesis of diabetic nephropathy. As such, we hypothesized that GFPT1, which encodes for GFAT, may confer genetic susceptibility to this complication among Caucasians. Screening of all known functional regions of GFPT1 revealed six single nucleotide polymorphisms (SNPs) that were located in the promoter, introns, and 3' untranslated region. The approximately 60 kb GFPT1 locus was encompassed in a single conserved haplotype block, and two tagging SNPs were sufficient to capture >90% of the haplotype diversity. Analysis of these SNPs in a case-control study made up of type 1 diabetic subjects (324 case subjects with diabetic nephropathy and 289 control subjects with normoalbuminuria despite >15 years of diabetes) revealed no significant association even after stratification by sex, diabetes duration, glucose control, and blood pressure. Similar results were obtained among type 2 diabetic subjects (202 case and 114 control subjects). Genetic variation in GFPT1 is thus unlikely to have a major impact on susceptibility to diabetic nephropathy.

Anisometropia in Singapore school children

PURPOSE

To report the prevalence rates of anisometropia in a school population and determine the relative contribution of refractive power and axial length to the measured anisometropia.

DESIGN

Population-based cross-sectional study.

METHODS

Autorefraction, keratometry, and ultrasonography studies were made.

SETTING

Three schools, located on the eastern, northern, and western part of Singapore.

STUDY POPULATION

In all, 1,979 children aged 7 to 9 years were recruited for this study. The study sample included Chinese (n = 1,481), Malay (n = 324), and Asian Indian (n = 174) children; 720 subjects have myopia (spherical equivalent <= -0.5 diopters) in at least one eye.

MAIN OUTCOME MEASURE

Anisometropia.

RESULTS

The prevalence rates of anisometropia, in terms of spherical equivalent (SE) difference of at least 1.5 diopters and 2.0 diopters were 1.57% (95% confidence interval [CI]: 1.1, 2.2) and 1.01% (95% CI: 0.6, 1.6), respectively. The prevalence rate of anisometropia (at least 2.0 diopters) among the children with at least one myopic eye was 2.4% (95% CI: 1.4, 3.8), whereas in those without any myopic eyes, the prevalence rate was only 0.2% (95% CI: 0.06, 0.8). The spherical equivalent difference between the right and left eyes was positively correlated with the difference in axial lengths (P <.001). The difference in corneal refractive power is not statistically different between the anisometropic and the nonanisometropic children.

CONCLUSIONS

The anisometropia prevalence rate in a childhood population with a relatively high prevalence of myopia was reported. The origin of the anisometropia is axial, and these results suggest that the differential rate of elongation between the two eyes of nonmyopic subjects results in anisometropia.

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.

Low birth weight in relation to parental occupations—a population-based registry in Singapore (1994–1998)

OBJECTIVES

To study the association between parental occupation and low birth weight (LBW) in infants born in Singapore between 1994 and 1998. Other factors that may be related to LBW were also investigated.

METHODS

A retrospective study. Information was obtained from the Singapore National Registry of Births and Deaths on parental occupations for live births between 1 January 1994 to 31 December 1998. Parental date of birth, ethnic group, and highest educational qualification were also obtained. The associations between these factors and the occurrence of LBW was assessed using descriptive statistics and logistic regression analysis.

RESULTS

A total 208,360 live births were studied. Analyses were restricted to singleton births > or =37th week gestation (total of 189,064). No significant differences in LBW risk were found for the different maternal occupational groups, compared with a referent group ("legislators, senior officers, and managers"). However, fathers who were "not working" (OR=2.04; 1.57-2.65), "not classifiable by occupation" (OR=1.34; 1.09-1.65), and "cleaners, laborers, and related workers" (OR=1.32; 1.12-1.55) had the highest risk of LBW infants when compared with "legislators, senior officers, and managers," after adjustment for maternal occupation, ethnic group, educational level and age, paternal educational level, infant gestational age, sex, and birth order.

CONCLUSION

Certain paternal occupational groups appear to be associated with a higher risk of having LBW infants. This may be linked to socioeconomic status and possible work-related factors. Future studies of pregnancy outcomes should not ignore the potential contributions of fathers.

Incidence and survival of mucinous adenocarcinoma of the colorectum: a population-based study from an Asian country

PURPOSE

Previous studies have shown conflicting results on the prognosis of mucinous adenocarcinoma of the colorectum. This could be because of heavy bias on patient selection. Furthermore, little data are available from Asian populations. This study was designed to examine incident and prognostic characteristics of mucinous adenocarcinoma of the colorectum based on data obtained from a population-based, Asian, cancer registry.

METHODS

A total of 627 of 15,762 were mucinous adenocarcinoma cases from invasive colorectal cancer patients registered in the Singapore Registry from 1968 to 1997. Age-standardized incidence rate was used to describe the incident pattern of mucinous adenocarcinoma of colon and rectum during a period of time. Survival of patients with mucinous adenocarcinoma or ordinary adenocarcinoma was compared using relative survival and proportional hazards model.

RESULTS

Age-standardized incidence rate of mucinous adenocarcinoma of the colon and rectum were almost unchanged in males, rising slightly in females during the study periods from 1968 to 1972 to 1993 to 1997. The proportion of mucinous adenocarcinoma cases was similar among genders and calendar-year periods but was higher in younger age groups, Malays and Indians, in advanced stages of the disease, and proximal colon. Five-year relative survival rate of patients with mucinous adenocarcinoma were similar in the colon but were lower in the rectum.

CONCLUSIONS

Colorectal mucinous adenocarcinoma as a different etiologic entity from other histologic types of colorectal cancer was suggested. Possibly greater aggressiveness of mucinous adenocarcinoma occurring in the rectum requires confirmation but suggests that mucin is important in the pathogenesis of mucinous adenocarcinoma.

Profound changes in breast cancer incidence may reflect changes into a Westernized lifestyle: A comparative population-based study in Singapore and Sweden

Breast cancer incidence in Sweden has always been approximately twice as high as in Singapore. In recent years, this difference is limited to postmenopausal women. The aim of this study was to explore the reasons behind these differences through the use of age-period-cohort modeling. This population-based study included all breast cancer cases reported to the Swedish and the Singapore cancer registries from 1968 to 1997, with a total of 135,581 Swedish and 10,716 Singaporean women. Poisson regression using age-period and age-cohort models was used to determine the effects of age at diagnosis, calendar period and birth cohort. Incidence rate ratios were used to summarize these effects. An age-cohort model provided the best fit to the data in both countries, indicating that changes over lifetime, rather than recent differences in medical surveillance, might account for the observed differences in these 2 populations. The changes over birth cohort were much greater among Singaporean women. The relative effect of age was very similar in the 2 countries. Analyses show that age and cohort effects may explain the differences in trends of female breast cancer incidence between Sweden and Singapore. The larger cohort effect seen in Singaporean women may be attributed to more rapid changes in reproduction and lifestyle patterns than that of Swedish women during the period studied. The incidence of breast cancer in postmenopausal women in Singapore will probably continue to rise in the coming decades to match the current Swedish rates.

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.

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.

Population-based survival for cervical cancer in Singapore, 1968-1992

OBJECTIVE

The aim of this study was to describe the cervical cancer survival rates in Singapore during the period of 1968 through 1992 using population-based data.

STUDY DESIGN

A review of cases with cervical cancer diagnosed between 1968 and 1992 from Singapore Cancer Registry was conducted. Information on vital status at December 31, 1997, was available for 3531 cases. Cumulative observed and relative survival rates were computed by using Hakulinen's method.

RESULTS

Survival in cervical cancer in Singapore has improved over the 25-year period. The overall 5-year age-standardized relative survival (ASRS) for all patients increased from 45% in 1968-1972 to 65% in 1988-92. Poorer survival rates were observed in elderly patients and Malays.

CONCLUSION

The improvement in survival of cervical cancer is likely to be attributed to the rapid national development of Singapore, resulting in the improvements in health services infrastructure and accessibility, as well as to the impact of widely available cytology-based screening resulting in early detection.

Urinary alpha1-microglobulin as a marker of nephropathy in type 2 diabetic Asian subjects in Singapore

OBJECTIVE

This study examines urinary alpha(1)-microglobulin as a marker of early nephropathy in type 2 diabetic Chinese, Malays, and Asian Indians in Singapore.

RESEARCH DESIGN AND METHODS

A cross-sectional study was performed on 590 consecutive type 2 diabetic patients (296 males, 294 females) who were on routine follow-up at a primary care clinic. Information was obtained from interviews, case notes, and blood and urine samples. Because the distribution of urinary alpha(1)-microglobulin levels was highly skewed, these levels were log-transformed, and geometric means were calculated. There was correction for variability in urine flow by dividing by urine creatinine levels, given as mg/mmol urine creatinine, and adjustment for confounding variables.

RESULTS

Urinary alpha(1)-microglobulin was higher in men than in women and was directly related to age, but no ethnic differences were apparent. It was directly related to duration of diabetes, with adjusted geometric means of 1.19 and 1.43 mg/mmol urine creatinine for a duration of <10 and > or =10 years, respectively (P = 0.07). Urinary alpha(1)-microglobulin was highest in patients on insulin, followed by those on oral medication and then those on diet alone (adjusted geometric means: 1.47, 1.36, and 0.86 mg/mmol urine creatinine, respectively; P = 0.01). Levels were also higher in patients with poor glucose control, as measured by HbA(1c), fasting plasma glucose, and 2-h postprandial plasma glucose (P < 0.01 for each). Urinary alpha(1)-microglobulin was directly related to albuminuria, with adjusted geometric means for normoalbuminuria, microalbuminuria, and macroalbuminuria of 1.06, 1.47, and 4.72 mg/mmol urine creatinine, respectively (P < 0.01). However, of patients with normoalbuminuria, 33.6% had raised urinary alpha(1)-microglobulin. Likewise, of patients with normal urinary alpha(1)-microglobulin, 27.6% had albuminuria.

CONCLUSIONS

Urinary alpha(1)-microglobulin was related to duration, severity, and control of diabetes. Urinary alpha(1)-microglobulin and albumin were directly related, but in some patients, one was present in the absence of the other. Hence, in addition to albuminuria (which measures glomerular dysfunction), urinary alpha(1)-microglobulin (which measures proximal tubular dysfunction) is useful for the early detection of nephropathy in diabetic subjects.

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.

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.

Component dependent risk factors for ocular parameters in Singapore Chinese children

OBJECTIVE

To examine the risk factors for variations in ocular biometry parameters in Singapore Chinese children, a population with a known high prevalence rate of myopia at an early age.

DESIGN

Cross-sectional study.

PARTICIPANTS

Children aged 7 to 9 years (n = 1453) from three schools in Singapore.

METHODS

The children underwent A scan biometry and cycloplegic autorefraction measurements. Questions were asked regarding number of books read per week, night lighting, and parental myopia.

MAIN OUTCOME MEASURES

Axial length, vitreous chamber depth, lens thickness, anterior chamber depth, refraction, and corneal curvature radius measurements were made.

RESULTS

After controlling for several factors, the axial lengths were found to be longer and vitreous chambers deeper in children who were older, male, read more than two books per week, or taller, and those who had at least one parent who was myopic. In these models, children who read more than two books per week had axial lengths that were 0.17 mm longer and vitreous chambers that were 0.15 mm deeper compared with children who read two or fewer books per week. Anterior chambers were deeper in males and taller children, whereas corneal curvature was steeper in female, older, and shorter children.

CONCLUSIONS

Increases of axial length and vitreous cavity depth were associated with older age, being male, reading more than two books per week, increased height, and parental history of myopia. Of these risk factors, however, neither reading nor parental myopia history were associated with values for anterior chamber depth, corneal curvature, or lens thickness. These findings confirm that conventional risk factors for myopia associated with the vitreous cavity, but suggest that anterior segment parameters such as corneal curvature and lens thickness may be subject to unrelated postnatal growth control mechanisms.

Interval cancers following breast cancer screening in Singaporean women

Our study reports on the interval cancers arising in the subsequent 3 years in women screened as part of the Singapore Breast Cancer Screening Programme that commenced in 1994. Women, the majority of Chinese ethnicity, were either invited or not invited by random allocation to be screened. All women, other than those identified with breast cancer at screening, whether invited or not, were followed for 3 years, and information on all breast cancers arising in this period was obtained through the national registry. In particular, the cancers arising from those women who were deemed free of the disease at screening were noted. The mammographs taken at screening of those women who developed such an interval cancer were rereviewed by 3 radiologists. In the 28,099 women who were screened and deemed free of disease, 59 interval cancers were reported with annual rates of 2.1, 10.6 and 10.8 per 10,000 women-years in the succeeding 3-year periods. In 39,425 women who were invited but declined screening, the rates were 17.0, 15.5 and 11.7, while the corresponding rates from 97,294 women not invited were 12.8, 13.3 and 13.0. Whereas the annual incidence at 1 year in women who have been screened is much lower than those in the 2 groups who were not screened, it is of a similar magnitude by 2 years. This suggests that locally an optimal screening interval may be close to 1 year. The rereview of the mammograms of those 59 women with interval cancers suggested that the maximum possible number of these that might have been detected at screening was 10 (17%).

Sensitivity and specificity of visual acuity screening for refractive errors in school children

PURPOSE

To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren.

METHODS

In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least -0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least -1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted.

RESULTS

A total of 1,028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively.

CONCLUSIONS

The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.

Population-based survival analysis of colorectal cancer patients in Singapore, 1968-1992

Since the 1980s, colorectal cancer incidence in Singapore has ranked second to lung in males and females. We describe a population-based analysis of survival of colorectal cancer patients diagnosed from 1968 to 1992 in Singapore. Data of colorectal cancer patients diagnosed during 1968-1992 were retrieved from the Singapore Cancer Registry. Patients were passively followed up for death to the end of 1997. The final dataset consisted of 10,114 subjects. Observed and relative survival rates were calculated by stage (localized, regional metastases and distant metastases), age, ethnicity and calendar period for both genders. Over the study period, a significant progress in survival of colorectal cancer patients was observed. For localized cancer of the colon, the 5-year age-standardized relative survival (ASRS) increased from 36% in 1968-1972 to 66% in 1988-1992 for males and from 32 to 71% for females. For localized rectal cancer, the 5-year ASRS improved from 25 to 66% for males and from 23 to 66% in females. Similarly, improvement was observed in colorectal cancer patients with regional metastases, but not in those with distant metastases. Calendar year period and clinical stage of disease were identified as major significant prognostic factors of survival for colorectal cancer. The substantially improved colorectal cancer survival rates reflected the interplay of cancer control activities in various areas, such as health promotion, early diagnosis and treatment. Our study shows a unique changing pattern of survival experience for colorectal patients from a country undergoing rapid economic development.

Height and its relationship to refraction and biometry parameters in Singapore Chinese children

PURPOSE

To examine the association between the anthropometric measurements of height, weight, body mass index (BMI) and refraction and other ocular parameters in Singapore Chinese children.

METHODS

In a cross-sectional study of 1449 Chinese schoolchildren, aged 7 to 9 years, from three Singapore schools, height and weight were measured according to standard protocol, and BMI was calculated. Refractive error and corneal curvature measures were determined by autorefraction in eyes under cycloplegia. Axial length, vitreous chamber depth, lens thickness, and anterior chamber depth were measured using A-scan biometry ultrasonography.

RESULTS

In comparison with the children with height in the first quartile for a given age and gender, the eyeball length in children in the fourth quartile was 0.46 mm longer, the vitreous chamber depth 0.46 mm deeper, the corneal radius of curvature 0.10 mm greater (i.e., flatter), refraction more negative by 0.47 D (-0.76 D versus -0.29 D), and axial length-to-corneal curvature radius (AL-CR) ratio higher, after analyses controlling for age, gender, parental myopia, reading, school, and weight. The associations of height with refractive error and AL-CR ratio were significant in girls but not in boys. Heavier and more obese children had refractions that were more hyperopic (P = 0.01, P = 0.08), after analyses controlling for age, gender, parental myopia, reading, and school (height was also controlled for if weight was evaluated). This association was present in boys but not in girls.

CONCLUSIONS

Controlling for age, gender, parental myopia, reading, school, and weight showed that taller Singapore Chinese children had eyes with longer axial lengths, deeper vitreous chambers, flatter corneas, and refractions that tended toward myopia. In multivariate analysis, eyes in children who were heavier or who had a higher BMI tended to have refractions that were more hyperopic, and eyes in heavier children had shorter vitreous chambers. Differences between the present results and a recent report in Singapore adults suggest either a cohort effect or a potential influence of systemic endocrine or metabolic factors during childhood on refractive development.

Nearwork in early-onset myopia

PURPOSE

To determine the relationship of nearwork and myopia in young elementary school-age children in Singapore.

METHODS

A cross-sectional study of 1005 school children aged 7 to 9 years was conducted in two schools in Singapore. Cycloplegic autorefraction, keratometry, and biometry measurements were performed. In addition, the parents completed a detailed questionnaire on nearwork activity (books read per week, reading in hours per day and diopter hours [addition of three times reading, two times computer use, and two times video games use in hours per day]). Other risk factors, such as parental myopia, socioeconomic status, and light exposure history, were assessed.

RESULTS

In addition to socioeconomic factors, several nearwork indices were associated with myopia in these young children. The multivariate adjusted odds ratio of higher myopia (at least -3.0 D) for children who read more than two books per week was 3.05 (95% confidence interval [CI], 1.80-5.18). However, the odds ratios of higher myopia for children who read more than 2 hours per day or with more than 8 diopter hours (1.50; 95% CI, 0.87-2.55 and 1.04; 95% CI, 0.61-1.78, respectively) were not significant, after controlling for several factors.

CONCLUSIONS

Children aged 7 to 9 years with a greater current reading exposure were more likely to be myopic. This association of reading and myopia in a young age cohort was greater than the strength of the reading association generally found in older myopic subjects. Whether these results identify an association of early-onset myopia with nearwork activity or other potentially confounding factors is discussed.