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Background South Asians are at ~2 fold higher risk of cardiovascular disease (CVD) than Europeans. Physical inactivity is an independent risk factor for CVD, and may be more common in South Asians than Europeans. However, published studies of physical activity in South Asians have all relied on self-report by questionnaire, an approach of limited accuracy, confounded by linguistic, cultural and reporting bias. Accelerometers are validated tools for measurement of physical activity energy expenditure (PAEE) in Europeans, but are influenced by body habitus and device positioning. The accuracy of accelerometers in South Asians is not known. Aims To identify the accelerometer and accelerometer position that most accurately quantifies physical activity amongst South Asians, and to compare the accuracy of the chosen accelerometer between South Asians and Europeans. Methods We investigated 57 South Asians and 29 Europeans undergoing an exercise treadmill test (ETT) for clinical indications. All participants completed the treadmill test while simultaneously wearing 3 commercially available accelerometers in manufacturer recommended positions: i. Actigraph GT3X (3 positions - ankle, waist and wrist); ii. Geneactiv (3 positions - ankle, waist and wrist) and iii. Actiheart (chest only). Each participant thus had 7 device-position combinations. Personal and medical history was collected by questionnaire, followed by anthropometric measurements (height, weight, waist and hip circumference). We used linear regression and Bland-Altman plots to investigate the relationships between PAEE measured by the accelerometers (Measured) and actual PAEE on the treadmill (Actual). Results The relationship between Measured and Actual PAEE was highest for the Actigraph GT3X in the ankle position (regression beta: 0.55+/-0.03, Table). Wrist-worn devices consistently displayed poor PAEE prediction. Measured and Actual PAEE were similar amongst South Asians and Europeans for all accelerometers and positions (P > 0.05), including the ankle-worn Actigraph GT3X. However, even the ankle-worn Actigraph GT3X underestimated PAEE, especially at high workload (Figure). Conclusion The Actigraph GT3X is the most accurate device for measuring PAEE amongst both South Asians and Europeans. PAEE is best measured by the ankle-worn accelerometers followed by waist-worn accelerometers. Our results will inform the design of future studies to investigate the relationship between physical activity and CVD in the two populations. Relationship between Measured and Actual energy expenditure [beta (SE), from regression] in South Asians and Europeans.

Background National mortality statistics report that UK Indian Asians are at approxiamately 2 fold higher risk of cardiovascular disease mortality compared with people of European ancestry. However, previous studies in North American and European populations suggest that up to 40% of death certificates are incorrect, leading to an overestimation of cardiovascular disease mortality. The validity of routine death certification amongst Indian Asians is unknown. Aims and methods We investigated the accuracy of routine death certification amongst UK Indian Asians, to determine whether incorrect certification contributes to the reported higher cardiovascular disease amongst Indian Asians. We reviewed all available medical records (hospital, primary care and coroner) for a representative sample of 315 Indian Asians and Europeans who died in London, UK between 2002 and 2011. Deaths were independently coded as cardiovascular or non-cardiovascular according to published international diagnostic criteria by 2 cardiologists; where there was disagreement a third adjudicated. Results Age of death was lower amongst Indian Asians than Europeans (66.6 ± 10.1 vs. 69.7 ± 8.2, P = 0.003). Compared to review of records, routine death certification overestimated cardiovascular disease as underlying cause of death amongst Indian Asians (33.6 vs. 29.6%, p Conclusion Routine death certification overestimates cardiovascular deaths by ~20% amongst UK Indian Asians and Europeans, but the accuracy of death certification is similar in the two populations. Inaccurate death certification does not contribute to higher reported cardiovascular disease mortality amongst Indian Asians compared to Europeans.