Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey

PURPOSE

To describe the variation in ocular biometry in adult Chinese individuals in Singapore.

METHODS

This study was a population-based, cross-sectional survey of adult Chinese persons aged 40 to 81 years residing in Tanjong Pagar district, Singapore. Axial ocular dimensions, including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were measured using an A-scan ultrasound device. Corneal curvature (CC) and noncycloplegic refraction were measured with an autorefractor, with refraction further refined subjectively. Lens nuclear opacity (NO) was graded clinically using the modified Lens Opacity Classification System III (LOCS III) score.

RESULTS

A total of 1717 subjects were eligible for the survey, of whom 1232 (71.8%) participated. Biometric and refraction data were available for 1004 (58.5%) phakic subjects. The AL, ACD, LT, VCD, CC, and LOCS III scores were 23.23 +/- 1.17 mm, 2.90 +/- 0.44 mm, 4.75 +/- 0.47 mm, 15.58 +/- 1.11 mm, 7.65 +/- 0.27 mm, and 3.2 +/- 0.9 (mean +/- SD), respectively. On average, people aged 40 to 49 years, when compared with those 70 to 81 years, had longer ALs (mean difference, +0.58 mm), deeper ACDs (+0.52 mm), longer VCDs (+0.72 mm), but thinner lenses (-0.70 mm) and less severe NO (-1.7 LOCS III score). CCs did not vary significantly with age. After controlling for age, women had shorter ALs and VCDs, shallower ACDs, but thicker lenses and steeper CCs than men. The variation in noncycloplegic refraction with age was nonlinear. Among people aged 40 to 59 years, a higher prevalence of hyperopia was seen in older compared with younger persons (on average, a difference of +1.3 D for every 10-year difference in age, P: < 0.001), explained principally by shorter AL (and VCD) in older persons. Among those 60 to 81 years, this pattern was not obvious (a difference of -0.03 D for every 10-year difference in age, P: = 0.12), as NO became an additional determinant of refraction, with greater degrees of NO in older person's driving refraction in the "minus" direction.

CONCLUSIONS

Ocular dimensions vary with age and gender in adult Chinese persons in Singapore. The variation in noncycloplegic refraction in people 40 years and older may be explained by differences in axial lengths (principally vitreous chamber depths) between older and younger persons and, from 60 years onwards, differences in lens nuclear opacification as well.

Prevalence and risk factors for refractive errors in adult Chinese in Singapore

PURPOSE

To determine the epidemiology of refractive errors in an adult Chinese population in Singapore.

METHODS

A disproportionate, stratified, clustered, random-sampling procedure was used to select names of 2000 Chinese people aged 40 to 79 years from the 1996 Singapore electoral register in the Tanjong Pagar district in Singapore. These people were invited to a centralized clinic for a comprehensive eye examination, including refraction. Refraction was also performed on nonrespondents in their homes. Myopia, high myopia, and hyperopia were defined as a spherical equivalent (SE) in the right eye of less than -0.5 D, less than -5.0 D, and more than +0.5 D, respectively. Astigmatism was defined as less than -0.5 D of cylinder. Anisometropia was defined as a difference in SE of more than 1.0 D between the two eyes. Only phakic eyes were analyzed.

RESULTS

From 1717 eligible people, 1232 (71.8%) were examined. Adjusted to the 1997 Singapore population, the overall prevalence of myopia, hyperopia, astigmatism, and anisometropia was 38.7% (95% confidence interval [CI]: 35.5, 42.1), 28.4% (95% CI: 25.3, 31.3), 37.8% (95% CI: 34.6, 41.1), and 15.9% (95% CI: 13.5, 18.4), respectively. The prevalence of high myopia was 9.1% (95% CI: 7.2, 11.2), with women having significantly higher rates than men. The age pattern of myopia was bimodal, with higher prevalence in the 40 to 49 and 70 to 81 age groups and lower prevalence between those age ranges. Prevalence was reversed in hyperopia, with a higher prevalence in subjects aged 50 to 69. There was a monotonic increase in prevalence with age for both astigmatism and anisometropia. Increasing educational levels, higher individual income, professional or office-related occupations, better housing, and greater severity of nuclear opacity were all significantly associated with higher rates of myopia, after adjustment for age and sex.

CONCLUSIONS

The results indicate that whereas myopia is 1.5 to 2.5 times more prevalent in adult Chinese residing in Singapore than in similarly aged European-derived populations in the United States and Australia, the sociodemographic associations are similar.

The prevalence of glaucoma in Chinese residents of Singapore: a cross-sectional population survey of the Tanjong Pagar district

BACKGROUND

Data on prevalence of glaucoma in East Asia are scarce.

OBJECTIVE

To determine the prevalence and clinical characteristics of glaucoma in adult Chinese Singaporeans.

METHODS

A group of 2000 Chinese people, aged 40 to 79 years, were selected from the electoral register of Tanjong Pagar district in Singapore using a disproportionate, stratified, clustered, random-sampling procedure. Glaucoma was diagnosed in people with an excavated optic neuropathy and a reproducible visual field defect or on the basis of severe structural disc abnormality alone, if reliable field results could not be obtained. The diagnosis was also made in blind subjects with raised intraocular pressure or previous glaucoma surgery.

RESULTS

Of 1717 eligible subjects, 1232 were examined, with a response rate of 71.8%. There were 45 cases of glaucoma: 27 were men and 18 were women. The main diagnoses were primary open-angle glaucoma (n = 22 [49%]), primary angle-closure glaucoma (n = 14 [31%]), and secondary glaucoma (n = 7 [16%]). It was not possible to determine the mechanism in 2 (4%).

CONCLUSIONS

The age-standardized prevalence of glaucoma was 3.2% (95% confidence interval, 2.3-4.1) in the population 40 years and older. Glaucoma was the leading cause of blindness. Primary angle-closure glaucoma and secondary glaucoma were the most visually destructive forms of the disease. Our findings suggest current projections of glaucoma prevalence among ethnic Chinese are a substantial underestimate. Arch Ophthalmol. 2000;118:1105-1111

Cloning and characterization of two hydrophobin genes differentially expressed during fruit body development in Lentinula edodes

Hydrophobins play important roles in morphogenesis and pathogenesis in fungi and fruit development in mushrooms. Two genes encoding hydrophobins (Le.hyd1 and Le.hyd2) were isolated during sequencing of random clones from a primordial cDNA library of Lentinula edodes. The nucleotide sequences of these two genes were determined. These two genes are 760 and 738 bp in length and the deduced amino acid sequences are homologous to various fungal hydrophobins with characteristic cysteine spacing. These hydrophobin genes are Class I hydrophobins judging by their conserved domains and hydropathy patterns. The transcript level of Le.hyd1 is high in primordium and that of Le.hyd2 is high in dikaryotic mycelial tissues. Poor expression of these two genes in monokaryotic parents indicates that these two genes are under mating-type regulation. We thus suggest that differential expression of these two L. edodes hydrophobins during fruit development may contribute to their distinct roles in fruiting of this mushroom.

The human bone marrow response to acute air pollution caused by forest fires

Atmospheric pollution increases cardiopulmonary morbidity and mortality by unexplained mechanisms. Phagocytosis of fine particles (PM(10)) by rabbit alveolar macrophages elevates white blood cells (WBC) by releasing precursors from the bone marrow and this could contribute to the pathogenesis of cardiopulmonary disease. The present study examined the association between acute air pollution caused by biomass burning and peripheral WBC counts in humans. Serial measurements of the WBC count made during the 1997 Southeast Asian Smoke-haze (Sep 29, Oct 27) were compared with a period after the haze cleared (Nov 21, Dec 5) using peripheral blood PMN band cells to monitor marrow release. The results showed that indices of atmospheric pollution were significantly associated with elevated band neutrophil counts expressed as a percentage of total polymorphonuclear leukocytes (PMN), with maximal association on zero and 1 lag day for PM(10) and 3, and 4 lag days for SO(2) (p value < 0.000). We conclude that atmospheric pollution caused by biomass burning is associated with elevated circulating band cell counts in humans because of the increased release of PMN precursors from the marrow. We speculate that this response contributes to the pathogenesis of the cardiorespiratory morbidity associated with acute air pollution.

Validity of symptom and clinical measures of asthma severity for primary outpatient assessment of adult asthma

BACKGROUND

Symptom and pulmonary function measures of asthma severity are used for severity classification in practice guidelines. However, there is limited methodological evidence in support of their validity and utility.

AIM

To validate initial symptom and forced expiratory volume (FEV1) measures of asthma severity with the subsequent risks of exacerbations resulting in emergency room (ER) visits, hospitalisation, and sickness absence from work. In addition, symptom-based measures of change in asthma severity were also evaluated against the concurrent risks of asthma exacerbations.

METHOD

A cohort of 361 adult asthmatic patients in general outpatient clinics was studied. At initial interview, frequencies of asthmatic symptoms and nocturnal exacerbations, FEV1, and a severity score combining these measures, were recorded. At re-interview in the third year, the frequencies of asthma exacerbations resulting in ER visits, hospitalisation, and sickness absence, and a self-assessed global measure of change in severity and serially-assessed change in symptom frequencies, were measured.

RESULTS

All individual symptom and FEV1 measures were strongly related to the subsequent risks of ER visits, hospitalisation, and sick absence. A severity score of more than 3 (moderate to severe asthma) and self-assessed change in asthma severity were most strongly and significantly associated with greatly increased risks of all outcomes. Individual symptoms and FEV1 measures alone did not show high sensitivities, but the severity score combining these measures gave much more satisfactory validity. Perhaps not surprisingly, self-assessed change in asthma appeared to give the most satisfactory validity.

CONCLUSION

These results support the validity and clinical utility of a simple clinical score based on symptom and FEV1 measures, and self-assessed measure of change in severity, for risk classification in contemporary clinical practice guidelines.

Temporal trends and ethnic variations in asthma mortality in Singapore, 1976-1995

BACKGROUND

A study was undertaken to examine temporal trends and ethnic differences in the asthma mortality rate in Singapore.

METHODS

Asthma mortality rates in Singapore were estimated from vital data for the years from 1976 to 1995. Trends in sex and age specific (5-14, 15-34, 35-59, 60+ years) rates were obtained for four periods (1976-80, 1981-85, 1986-90, 1991-95) and for Chinese, Malay, and Indian subjects for the years when these data were available (1989-95).

RESULTS

An increase in asthma mortality was observed in children aged 5-14 years from 0.21 per 100,000 person years in 1976-80 to 0.72 per 100,000 person years in 1991-95. No increases were noted in the other age groups but a small decrease was observed in the 1991-95 period for the 35-59 year age group. Marked ethnic differences in mortality rates were observed. In the group aged 5-34 years the asthma mortality rates were 0.5 per 100,000 in Chinese subjects, 1.3 per 100,000 in Indians, and 2.5 per 100,000 in Malay subjects. Similar 2-4 fold differences were observed in all other age groups.

CONCLUSIONS

Apart from genetic factors, environmental exposures and medical care factors which influence asthma prevalence and severity are most likely to be the causes of the observed temporal trends and ethnic differences in the asthma mortality rate in Singapore, but further studies are needed to elucidate these more fully.

Adult asthma prevalence, morbidity and mortality and their relationships with environmental and medical care factors in Singapore

We have conducted a series of studies on adult asthma in Singapore that describe the prevalence, morbidity and mortality and their relationships with environmental and medical care factors. There was no evidence of a temporal increase of mortality from 1976 to 1995 for adults. The prevalence rate of asthma is 2.4% in men and 2.0% in women. There is considerable morbidity among asthmatics, corticosteroids are under-used, and patients' knowledge and self-management skills is poor. Increased morbidity is significantly associated with current keeping of pets, current smoking, and the patients' knowledge and self-management skills. Occupational exposure contributes up to a third of asthma morbidity. Malays and Indians have higher rates of asthma mortality and morbidity than Chinese. They have greater exposures to airborne allergens from keeping rugs or carpets, and pets. Malays experience the most morbidity from asthma, but make less use of health services, and receive less medical attention, than Indians or Chinese.

Long-term outcome and disease control in near-fatal asthma

Patients who have survived an episode of intubation and mechanical ventilation for acute respiratory failure due to a severe and unresponsive asthmatic attack are considered to have experienced a near-fatal asthma (NFA) attack. Such patients are at a higher risk of similar severe attacks and hence of death in the future. The aims of the study were to: (i) evaluate the outcome; (ii) identify any persistent deficiencies in asthma management, and (iii) assess self-management knowledge in survivors of NFA. Ninety-three consecutive patients who had been treated for NFA in the Intensive Care Unit of an urban teaching hospital in Singapore from 1992 to 1997 were studied. All hospital records were reviewed retrospectively. Survivors were then invited to attend a questionnaire interview and to have lung function tests performed. Of the original cohort (OC) of 93 patients with NFA (mean age 55.2 years), 18 (19% OC) patients (mean age 64 years) had died while in hospital and 75 (81% OC) patients survived the initial episode of NFA and were discharged home (DH). The long-term outcome of this DH group was: 13 patients had died (17% DH) and 62 (83% DH) survived. Of these survivors, 35 were interviewed while 27 declined or were not contactable. This interview yielded the following information: (i) Hospitalisation in the past year: 66% had no hospital admission; of the 31.4% who had 2 or more admissions, most had a further NFA attack. (ii) Health care: The majority of patients (71.4%) were monitored by a single doctor. (iii) Patient knowledge of disease management was deemed good to fair for trigger avoidance (77%), for appropriate drug usage (97%). (iv) Satisfactory inhaler skill (80%). NFA is associated with a high intrahospital and long-term mortality. Although most survivors of NFA appeared to have satisfactory care and a fair understanding of medication usage, a significant minority continue to pose much morbidity and risk for death.

Trends in mortality, incidence, hospitalisation, cardiac procedures and outcomes of care for coronary heart disease in Singapore, 1991-1996

In this study, we used Singapore population-based data from 1991 to 1996 to examine recent trends in mortality, incidence and hospitalisation for acute myocardial infarction (AMI), and explored the roles of primary prevention and medical care interventions in explaining these trends. We examined trends in medical interventions, namely coronary angiography (catheterisation), coronary artery bypass graft (CABG), and percutaneous transluminal coronary angioplasty (PTCA), length of stay, and payment methods, and explored the roles of technological, healthcare financing and delivery, and regulatory factors in influencing the diffusion and outcomes of these medical interventions. During the period 1991 to 1996, there were parallel declines in resident population rates of mortality, incidence and hospitalisation for AMI. The rates of angiograms, CABG and PTCA among residents also increased greatly, with the greatest increase among elderly aged 60 years and above. The rates of invasive cardiac procedures for AMI were all lower in females than in males. The population case-fatality rate of AMI declined slightly only for persons below 40 years of age. The case-fatality rate was higher in females than in males. The number of hospitalisations and cardiac procedures all rose sharply, and was phenomenal for PTCA (247%). The increase in volume of resource use was starkly greater in private hospitals than in restructured hospitals. The ratios of PTCA to CABG from 1991 to 1996 for private and restructured hospitals showed a greater rate of technology substitution in restructured hospitals than in private hospitals. The average length of stay (LOS, 6.7 days) was fairly constant in restructured hospitals. For private hospitals, LOS declined from 7.6 days in 1991 to 5.6 in 1996. LOS varied little among individual restructured hospitals, but widely among private hospitals. The most common method of payment for AMI hospitalisation was Medisave alone (50%), but for CABG surgery, the proportion of payment made through this method was only 12%. Out-of-pocket payments, Medisave, Medishield and private insurance have increased steadily. These data indirectly suggest that primary prevention and medical care interventions might have begun to succeed in reducing the rates of coronary heart disease in Singapore. The sharp increases in cardiac procedures may be explained by changing supply and demand factors for care of AMI and chronic ischaemic heart disease, including consumer preference for cardiac procedures, overuse of medical intervention, and technological change. More studies are needed to test these hypotheses.

Validation of the MOS SF-36 for quality of life assessment of patients with systemic lupus erythematosus in Singapore

OBJECTIVE

To assess the reliability and construct validity of the Medical Outcomes Study Short Form 36 Health Survey (SF-36) in a multiracial cohort of Asian patients with lupus in Singapore.

METHODS

A cross sectional study was performed on 118 English speaking patients with lupus attending a specialist rheumatology unit between March and August 1996. Patients completed a questionnaire containing the UK standard version of the SF-36 twice within a 14 day period. All patients were assessed for disease activity using the British Isles Lupus Assessment Group score (BILAG), and for disease related damage using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index (DI). Relationships between SF-36, BILAG, and DI scores were studied using Spearman's rank correlation. Internal consistency of the SF-36 was assessed using Cronbach's alpha, and stability using the repeatability coefficient of Bland and Altman.

RESULTS

SF-36 subscales showed high internal consistency, with Cronbach's alpha coefficient ranging from 0.84 to 0.94. Test-retest reliability was acceptable, with Spearman's rank correlation >0.70 for all subscales except role-physical, and mean differences in test scores of <2 points for 5 of 8 subscales. SF-36 subscale scores were weakly correlated with BILAG scores (Spearman's p -0.37 to 0.15) and SLICC/ACR DI scores (Spearman's p -0.25 to 0.23), suggesting divergent construct validity of the SF-36.

CONCLUSION

These data suggest the SF-36 is a reliable and valid measure of the quality of life of patients with lupus in Singapore.

Prevalence of snoring and sleep breathing-related disorders in Chinese, Malay and Indian adults in Singapore

This study investigated the prevalence of snoring and symptoms of sleep breathing-related disorders in the multi-ethnic population of Singapore (3 million people, comprising 75% Chinese, 15% Malay and 7% Indian). A multistaged, area cluster, disproportionate stratified, random sampling of adults aged 20-74 yrs was used to obtain a sample of 2,298 subjects (65% response), with approximately equal numbers of Chinese, Malay and Indian and in each 10 yr age group. An interviewer-administered field questionnaire was used to record symptoms of snoring and breathing disturbances during sleep witnessed by a room-mate and other personal and health-related data. The weighted point estimate (and 95% confidence interval) of the whole population prevalence of snoring was 6.8% (53-83). There were pronounced ethnic differences among Chinese, 6.2% (4.4-8.1); Malay, 8.1% (6.1-10.2) and Indian, 10.9% (85-13.4). The minimum whole population prevalence by the most restricted symptom criteria for defining sleep breathing-related disorder was 0.43% (0.05-0.8%). Similar marked ethnic differences in rates were observed using various symptom criteria. The ethnic differences in sleep breathing symptoms paralleled the differences in body mass index, neck circumference and hypertension, but statistically significant differences remained after adjustment for sex, age and these known associated factors. Marked ethnic differences in snoring and sleep breathing-related disorders were observed in Chinese, Malays and Indians in Singapore, which were only partly explained by known factors of sex, age and body habitus.

Studying the mental health of a nation: a preliminary report on a population survey in Singapore

AIM

A Singapore Mental Health Survey was designed to study the prevalence and pattern of psychiatric morbidity of the general population. Community surveys reveal the true pattern of mental disorders, free from any self-selection into, or referral within the health care system.

METHODS

A cross-sectional survey design was used to estimate the point prevalence of minor psychiatric morbidity (MPM) in an area-probability sample drawn from different regions. Disproportionate quota sampling yielded approximately equal numbers of Chinese, Malays and Indians for inter-ethnic comparison. The General Health Questionnaire, 28-item version (GHQ-28) measured psychoemotional symptoms in 3,020 subjects aged between 13-65 years. The GHQ-28 was validated against ICD-10 psychiatric diagnoses derived from structured psychiatric interview with the Composite International Diagnostic Interview (CIDI).

RESULTS

The optimal cut-off point for the GHQ-28 was determined to be 4/5 for Chinese, and 5/6 for Malays and Indians. Using the validated ethnic-specific cut-offs, MPM rate for Chinese was 17.4%, Malays 15.1% and Indians 17.8%. The population MPM prevalence rate was estimated to be 16.6% after standardisation with population census data. Specific types of ICD-10 psychiatric disorders which give rise to MPM were mainly anxiety and depressive disorders. Twelve percent of individuals with MPM had at least one ICD-10 disorder in the previous year.

CONCLUSION

Two-staged methodology is an efficient, cost-effective approach to study population prevalence of mental illness. Screening instruments utilised should be validated specifically for the culture and setting. Information from population surveys of psychiatric morbidity are important for the planning of mental health services for the country.

Lung cancer among Chinese females in Singapore 1968-1992: time trends, dialect group differences and implications for aetiology

BACKGROUND

Chinese females are distinguished internationally as having relatively high lung cancer incidence rates despite a low prevalence of cigarette smoking. In Singapore, this population comprises several dialect groups which have origins in different regions in China, each with its own traditional cultural practices.

METHODS

An analysis of 4029 incident cases of the disease notified to the Singapore Cancer Registry for 1968-1992 was undertaken to provide some insight into important aetiologic factors among these women.

RESULTS

The age-standardized incidence rate of lung cancer rose from 17.3 per 100,000 woman-years in 1968-1972 to 23.0 in 1978-1982 before falling off in more recent years. Age-period-cohort analysis indicated significant period and birth cohort effects, with the risk being highest for women born around 1908. Between the major dialect groups, Cantonese women had a significantly high rate compared with Hokkiens (relative risk [RR] = 2.6, 95% CI: 2.4-2.8). Histologically, there appears to be an increase in the proportion of adenocarcinomas diagnosed over this period (25.8% in 1968-1972 to 51.3% in 1988-1992).

CONCLUSION

Our results suggest that traditional practices which have decreased over the years, and are more prominent among Southern Chinese, may play a part in the aetiology of lung cancer locally.

Occupational asthma caused by orangutan in a zoo animal handler

A zoo animal handler developed bronchial asthma for the first time from handling orangutans (Pongo pygmaes). He had prior allergic reactions (rhinoconjunctivitis and urticarial rash), but no asthma, to deer and other hoofed animals in the zoo. In a worksite challenge, immediate and late onset of asthmatic symptoms and airflow obstruction were provoked by carrying a baby orangutan for about 20 minutes.

Risk factors and clinical outcomes between fungal and bacterial keratitis: a comparative study

PURPOSE

Previous studies on fungal and bacterial keratitis were descriptive single case series analysis. We conducted a hospital-based retrospective study to evaluate fungal and bacterial keratitis using a case-control design to compare risk factors and clinical outcomes.

METHODS

Twenty-nine cases of culture-positive fungal keratitis seen over a 5-year period were compared to 51 cases of culture-positive bacterial keratitis seen over a 21 months period. Using bacterial keratitis as the reference group, case-control odds ratios (OR) for predisposing factors and cohort relative risks (RR) for clinical outcomes associated with fungal keratitis were derived. Mantel-Haenszel adjustment procedures were used to examine the respective roles of confounding and intermediate variables.

RESULTS

Compared to bacterial keratitis, fungal keratitis was significantly more likely to be associated with ocular trauma (OR = 2.69, 95% confidence interval [CI], 1.06-6.86) but significantly less likely to be associated with contact lens wear (OR = 0.16, 95% CI, 0.04-0.67) and preexisting ocular diseases (OR = 0.23, 95% CI, 0.07-0.72). Fungal keratitis was more likely to perforate than bacterial keratitis (RR = 5.28, 95% CI, 1.35-20.66) and to require penetrating keratoplasty (OR = 5.86, 95% CI, 2.06-16.69).

CONCLUSIONS

Fungal keratitis appears more likely to result from ocular trauma, whereas bacterial keratitis is more likely to result from contact lens wear and pre-existing ocular diseases. Fungal keratitis is more likely than bacterial keratitis to result in perforation and require penetrating keratoplasty.

Population based standards for pulmonary function in non-smoking adults in Singapore

Ethnic differences in lung function are well recognized, hence the use of normative data should therefore be based on reference equations that are derived specifically for different ethnic groups. We have collected data (n = 406) for population-based reference values of lung function from randomly selected samples of healthy non-smoking adults of both gender (aged 20-79 years) for each of the three major ethnic groups (Chinese, Malay and Indians) in Singapore. Lung function forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, diffusion capacity (transfer factor) for carbon monoxide (DLCO), total lung capacity (TLC), residual volume (RV), RV/TLC and functional residual capacity (FRC) was measured using standardization procedures and acceptability criteria recommended by the American Thoracic Society. Lung function values were predicted from age, height, weight, body mass index (BMI) and transformed variables of these anthropometric measures, using multiple regression techniques. Ethnic differences were demonstrated, with Chinese having the largest lung volumes and flow rates, and Indians the smallest. These prediction equations provide improved and additional (TLC, RV, RV/TLC, FRC) population-based reference values for assessment of pulmonary health and disease in Singapore.

Initial construct cross-cultural validation of the Short Form 36 for quality of life assessment of systemic lupus erythematosus patients in Singapore

The objective of this study was to determine if the Short Form 36 (SF-36) Health Survey Questionnaire measures differences in quality of life between lupus patients and healthy controls in Singapore. A cross-sectional pilot study was conducted on consecutive English-speaking, female Chinese lupus patients seen at a Rheumatology unit. Healthy volunteers were recruited as controls during the same time period. All subjects completed the United Kingdom version of the SF-36. Lupus disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index and converted to a global score. Lupus-related damage was measured using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACRDI). The main outcomes measured were the mean SF-36 scale scores for lupus patients and healthy controls. Thirty-six lupus patients and 76 controls were included in the study. All subjects were English-speaking, Chinese female between 21 and 53 years of age. The mean age of patients and controls was 31.9 and 29.0 years respectively. Lupus patients had lower mean scale scores than controls for physical functioning (73.0 versus 89.7, P < 0.0027), bodily pain (71.0 versus 81.4, P < 0.027), physical role functioning (55.7 versus 89.5, P < 0.0001) and general health (47.4 versus 51.8, P < 0.05). Mean scale scores for vitality, social and emotional role function and mental health were similar in both groups. Ten patients had active disease (BILAG global scores of 3 to 14) and 13 patients had lupus-related damage (Damage Index scores of 1 to 7). These preliminary data suggest that the SF-36 Health Survey may be able to measure differences in quality of life between lupus patients and healthy controls in Singapore.

Accurate intraocular pressure measurement in contact lens wearers with normal pressures

PURPOSE

The purpose of this study was to evaluate a modified technique of Goldmann applanation tonometry without the use of fluorescein or anesthesia in normal eyes with contact lenses and to compare this technique with Tono-Pen tonometry.

METHODS

The intraocular pressure (IOP) of 40 normal eyes from 20 volunteers (mean age 25.6 years, range 22-35 years) was measured with and without-1.0 D disposable soft contact lenses in a prospective, masked, randomized study using Goldmann and Tono-Pen tonometry. Goldmann tonometry was performed without fluorescein or anesthesia with contact lenses on. IOP measurement using conventional Goldmann tonometry with fluorescein and without contact lens wear was employed as the standard for comparison.

RESULTS

Goldmann tonometry without fluorescein underestimated IOP levels in a consistent manner, with a bias of -2.15 mmHg (SD +/- 1.97). Goldmann tonometry without fluorescein, in the presence of a contact lens, consistently underestimated IOP levels by -2.90 mmHg (SD +/- 2.37), suggesting that IOP measurement is largely unaffected by the presence of a -1.00 D soft contact lens on the eye. In contrast, Tono-Pen tonometry consistently overestimated IOP levels by +3.93 mmHg (SD +/- 2.17). Given the limits of agreement, these results were fairly consistent.

CONCLUSIONS

The modified technique of Goldmann tonometry without fluorescein reflects standard Goldmann tonometry with fluorescein after a correction factor of +2 mmHg in normal eyes. IOP measurement by this technique does not appear to be significantly affected by the presence of a -1.0 D soft contact lens on the cornea.

Seasonal variation of fractures of the hip in elderly persons

A prospective study was made of 1500 elderly patients who suffered from acute hip fractures from 1986 to 1990. There were 36 per cent more fractures in the 6 colder months from November to April than in the rest of the year (P < 0.001). A strong correlation between the monthly adjusted fracture rate and the average lowest ambient temperature was also observed (P < 0.001). The fractures occurred in the older and less active patients during the 6 colder months. More importantly, they needed to wait longer for the operation during this 'high' season. This might be responsible for the higher medical complication rate after the operation. Better health care planning to help with the increased patient load in the 'high' season is essential to reduce the waiting time for the operation and the postoperative medical complication rate.

Asthma self care efficacy and morbidity in polyclinic outpatients

The new guidelines for the management of asthma require patients to participate in the management of their condition by exercising a high level of decision-making skills in self treatment. We evaluated the self care efficacy and morbidity of 198 asthmatic patients in primary care clinics and examined the factors likely to influence these management outcomes. About 70% of the patients were considered by conventional criteria to have significant morbidity requiring medical supervision. The most significant factors determining morbidity were knowledge of medications and attack management skills. Only a minority of the patients had satisfactory levels of these skills and knowledge. A high level of stigmatization from asthma was generally present among the patients but most of them appeared to possess a high level of self-confidence in the management of their asthma. These factors were also associated with asthma morbidity, but they were as likely to have resulted from morbidity as to have influenced it. The patients' attitude towards medications were mostly negative but their confidence in their doctors and their level of family support were high; none of these factors, however, were associated with morbidity. Attack management skills as a behavioural measure of self care efficacy was not significantly predicted by any of these personal or psychosocial factors. A practical implication of these findings is that asthma self management should focus on developing specific knowledge and skills in the self treatment of asthma attacks.

Ventilatory function measured with the Micro Spirometer: performance evaluation and reference values

The performance of the Micro Spirometer was compared with that of the Vitalograph by assessing the extent of agreement between the instruments and the repeatability of measurements with each instrument. The Micro Spirometer tended to give lower readings of forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) than the Vitalograph, with wide limits of agreement. The values of these ventilatory functions measured with the Micro Spirometer were, therefore, not directly comparable with those obtained from the Vitalograph, and it is also not satisfactory to predict readings on the Micro Spirometer from those made on the Vitalograph. In the management of asthma patients, the PEFR would still be preferably measured with the mini Wright peak flow, given its low cost and established reliability compared with the standard Wright peak flow meter. The Micro Spiromoter has the practical advantages of portability, ease of operation and relative cheapness for the baseline and long-term assessment of FEV1 and FVC in ambulatory care, as well as in epidemiological studies. However, local users should not employ reference values provided by the manufacturer or those published in the literature, but those reported in this paper.

Asthma in chemical workers exposed to aliphatic polyamines

Following the identification of an index case of occupational asthma, we assessed the respiratory morbidity in 12 workers exposed to aliphatic polyamines in a chemical factory and in 60 unexposed workers in three other workplaces. Many amine workers reported symptoms of chronic cough (7/12), chronic phlegm (9/12), wheezing (4/12) and exertional breathlessness (3/12). These were significantly more frequent in exposed than in unexposed workers (P < 0.01). They also had significantly greater diurnal variation in peak expiratory flow rates (DV-PEFR) than the unexposed workers (P < 0.01). All four amine workers with wheezing reported onset of symptoms after employment at the factory, and all had DV-PEFR greater than 15%, compared to only one control worker (P < 0.01). A second case of occupational asthma was confirmed by bronchial challenge test. The study indicated a very high risk of asthma and chronic airways disease and a need for stringent measures to protect the health of industrial workers exposed to aliphatic amines in Singapore.

Understanding asthma: patient survey

Eight hundred and two adult patients attending five randomly selected polyclinics in Singapore were interviewed to assess their understanding of asthma. Knowledge of asthma mechanism and its medications was poor with a mean score of 1.4 (median: 1) out of a total score of 6. About a third knew that asthma is due to narrowing of airways and a quarter knew the action of bronchodilators. Only 4.4% (27) knew that steroids decrease airway swelling or inflammation. The best knowledge score was associated with subjects who had the highest education, who had a family history and who had been exposed to pamphlets and books. Incorrect use of prophylaxis was also evident with only one-third (37%) using steroid inhalers regularly as prescribed. Only half (54.5%) of those with no schooling used the correct inhaler technique. Doctors were a source of information for only 49.9% (400) of the patients and it was those with the highest education who were most likely to get information from the doctors. Pamphlets were a source of information for less than one-fifth (16.2%) of the subjects. Greater emphasis should be given to patient education by doctors to help patients understand asthma and its treatment. Important target groups are the older, lesser educated and the moderate or severe patients on steroid inhalers.

Postural stability of workers exposed to lead

OBJECTIVE

To detect, with a computerised postural sway measurement system, any significant deviation of postural sway parameters among lead workers compared with a control group.

METHODS

Postural stability was investigated with a computerised postural sway measurement system in 60 workers exposed to lead with a duration of exposure of 84 (range 3-366) months and 60 controls. Sway parameter data were collected with an Advanced Mechanical Technology computerised biomechanics platform system.

RESULTS

The mean current blood lead concentration was 36.0 (range 6.4 to 64.5) micrograms/dl for the exposed workers and 6.3 (range 3.1 to 10.9) micrograms/dl for the 14 controls. There was no significant difference between the groups for the postural sway parameters obtained when the eyes were open. Significant differences were found for Xs, Ys (SDs of the coordinates of the centre of pressure); Xm, Ym (mean deviation of the coordinates of the centre of pressure); Rm (average displacement of Xi, Yi, from Xo, Yo); L (length of sway path); Vel (mean velocity of the centre of pressure along its path); Ao (area included within the path of the centre of pressure); Ae (95% confidence elliptical area). The Romberg ratios (the relation between eyes closed and open) for the Vel, L, Ao and Ae of the exposed workers were also significantly different from the controls.

CONCLUSION

The study showed that workers exposed to lead had significantly poorer postural stability than the controls. Lead may affect certain parts of the whole sensory neural axis resulting in postural instability when the visual input is cut off. Based on current blood lead concentrations, we were not able to obtain any significant association with the postural sway parameters.