PURPOSE: Information regarding mediators of differences in bone mineral density (BMD) among Asian ethnicities are limited. Since the majority of hip fractures are predicted to be from Asia, differences in BMD in Asian ethnicities require further exploration. We compared BMD among the Chinese, Malay, or Indian ethnicities in Singapore, aiming to identify potential mediators for the observed differences.
METHODS: BMD of 1201 women aged 45-69 years was measured by dual-energy X-ray absorptiometry. We examined the associations between ethnicity and BMD at both sites, before and after adjusting for potential mediators measured using standardized questionnaires and validated performance tests.
RESULTS: Chinese women had significantly lower femoral neck BMD than Malay and Indian women. Of the more than 20 variables examined, age, body mass index, and height accounted for almost all the observed ethnic differences in femoral neck BMD between Chinese and Malays. However, Indian women still retained 0.047 g/cm2 (95% CI, 0.024, 0.071) higher femoral neck BMD after adjustment, suggesting that additional factors may contribute to the increased BMD in Indians. Although no crude ethnic differences in lumbar spine BMD were observed, adjusted regression model unmasked ethnic differences, wherein Chinese women had 0.061(95% CI, - 0.095, 0.026) and 0.065 (95% CI, - 0.091, 0.038) g/cm2 higher lumbar spine BMD compared to Malay and Indian women, respectively.
CONCLUSION: BMD in middle-aged Asian women differ by ethnicity and site. Particular attention should be paid to underweight women of Chinese ethnic origin, who may be at highest risk of osteoporosis at the femoral neck and hence hip fractures.
METHODS AND RESULTS: For 12 years, we followed a prospective nationwide cohort of 15 151 patients (aged 22-101 years, median age 63 years; 72.3% male; 66.7% Chinese, 19.8% Malay, 13.5% Indian) who were hospitalized for acute myocardial infarction between 2000 and 2005. There were 6463 deaths (4534 cardiovascular, 1929 noncardiovascular). Compared with men, women had a higher risk of cardiovascular death (age-adjusted hazard ratio [HR] 1.3, 95% CI 1.2-1.4) but a similar risk of noncardiovascular death (HR 0.9, 95% CI 0.8-1.0). Sex differences in cardiovascular death varied by ethnicity, age, and time. Compared with Chinese women, Malay women had the greatest increased hazard of cardiovascular death (HR 1.4, 95% CI 1.2-1.6) and a marked imbalance in death due to heart failure or cardiomyopathy (HR 3.4 [95% CI 1.9-6.0] versus HR 1.5 [95% CI 0.6-3.6] for Indian women). Compared with same-age Malay men, Malay women aged 22 to 49 years had a 2.5-fold (95% CI 1.6-3.8) increased hazard of cardiovascular death. Sex disparities in cardiovascular death tapered over time, least among Chinese patients and most among Indian patients; the HR comparing cardiovascular death of Indian women and men decreased from 1.9 (95% CI 1.5-2.4) at 30 days to 0.9 (95% CI 0.5-1.6) at 10 years.
CONCLUSION: Age, ethnicity, and time strongly influence the association between sex and specific cardiovascular causes of mortality, suggesting that health care policy to reduce sex disparities in acute myocardial infarction outcomes must consider the complex interplay of these 3 major modifying factors.
MATERIALS AND METHODS: This was a retrospective descriptive study. We identified 1041 patients (810 Chinese, 139 Malays, 92 Indians) without previous history of cardiovascular disease who underwent cardiac computed tomography for atypical chest pain evaluation. A cardiologist, who was blinded to the patients' clinical demographics, reviewed all scans. We retrospectively analysed all their case records.
RESULTS: Overall, Malays were most likely to be active smokers (P = 0.02), Indians had the highest prevalence of diabetes mellitus (P = 0.01) and Chinese had the highest mean age (P <0.0001). The overall prevalence of patients with non-calcified plaques as the only manifestation of sub-clinical coronary artery disease was 2.1%. There was no significant difference in the prevalence of CAC, mean CAC score or prevalence of non-calcified plaques among the 3 ethnic groups. Active smoking, age and hypertension were independent predictors of CAC. Non-calcified plaques were positively associated with male gender, age, dyslipidaemia and diabetes mellitus.
CONCLUSION: The higher MI rates in Malays and Indians in Singapore cannot be explained by any difference in CAC or non-calcified plaque. More research with prospective follow-up of larger patient populations is necessary to establish if ethnic-specific calibration of CAC measures is needed to adjust for differences among ethnic groups.