The aim of this study was to identify occupational risk groups which might usefully be targeted for occupational asthma surveillance and control, using a community-based case-control approach. Data on previous and current occupations held by subjects were analyzed for 787 adult patients with bronchial asthma and 1591 nonasthmatic patient controls, aged 20-54 years, belonging to the three major races (Chinese, Malays, and Indians) in five outpatient primary care polyclinics. Odds ratios (OR) and 95% confidence intervals (95% CI) of association were adjusted for sex, age, race, smoking, and clinical atopy. No associated risks of asthma were found for clerical or sales workers in general. Significantly reduced risks of association with asthma were found for professional, technical, administrative, and managerial occupations (OR, 0.62; 95% CI, 0.47-0.82). The associated risks of asthma were generally elevated for service workers (OR, 1.35; 95% CI, 1.04-1.74) and manufacturing production and related workers (OR, 1.49; 95% CI, 1.23-1.81). Among them, increased risks were observed for cleaners, particularly municipal cleaners and sweepers (OR, 1.91; 95% CI, 1.22-2.99), textile workers (OR, 5.83; 95% CI, 1.93-17.57), garment markers (OR, 1.61; 95% CI, 1.01-2.58), electrical and electronic production workers (OR, 1.36; 95% CI, 1.06-1.75), printers (OR, 2.24; 95% CI, 1.17-4.31), and construction/renovation workers (OR, 2.24; 95% CI, 1.30-3.85). The odds ratio of association of asthma with exposures in service and production-related occupations overall, relative to the "nonexposed" reference group of nonmanual professional/technical, administrative/managerial, clerical, and sales occupations, was estimated to be 1.72 (95% CI, 1.36-2.19); the estimated population attributable risk was 0.33 (95% CI, 0.22-0.44).

AIM:The objectives of this study are: (1) to study the relation between body mass index (BMI), percentage-weight-for-height (PWH) and percentage body fat (PBF) in Singaporean Chinese children; (2) to assess the applicability of an international definition of obesity (the International Obesity Task Force (IOTF) BMI) as a screening tool to detect childhood obesity, as compared with the current Singapore population-specific definition using PWH. METHODS: A total of 623 Chinese children aged 6-11 y (321 males, 302 females) were recruited from a school by proportionate (40%) stratified random sampling. BMI and PWH were calculated from weight and height, while PBF was derived using leg-to-leg bioelectrical impedance analysis. The strength of association among the three indices of obesity was assessed using Spearman's correlation coefficient. Obese children were defined as those above the 95th percentile of PBF in each agegender-specific group. Sensitivity and specificity of IOTF-BMI cutoff values and PWH cutoff values were compared by testing their ability to correctly identify obese children. RESULTS: All three indices correlated well with one another (BMI:PWH r ¼ 0.83, BMI:PBF r ¼ 0.87, PWH:PBF r ¼ 0.76). Prevalence of obesity was lower using IOTF-BMI cutoffs (6.9%) than using PWH cutoffs (16.4%). The sensitivity and specificity of IOTF-BMI cutoff values were 75.0 and 96.0%, respectively, with sensitivity differing between boys (83.3%) and girls (66.6%) (P ¼ 0.35). In comparison, PWH cutoff values had higher sensitivity (91.6%) but lower specificity (86.6%), with no significant difference between the genders. CONCLUSION: IOTF-recommended BMI cutoff values had low sensitivity and may underestimate the local prevalence of childhood obesity. For screening purposes, we recommend that population-specific measures rather than international cutoff values be used.

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