BackgroundNew fitness trackers and smartwatches are released to the consumer market every year. These devices are equipped with different sensors, algorithms, and accompanying mobile apps. With recent advances in mobile sensor technology, privately collected physical activity data can be used as an addition to existing methods for health data collection in research. Furthermore, data collected from these devices have possible applications in patient diagnostics and treatment. With an increasing number of diverse brands, there is a need for an overview of device sensor support, as well as device applicability in research projects.ObjectiveThe objective of this study was to examine the availability of wrist-worn fitness wearables and analyze availability of relevant fitness sensors from 2011 to 2017. Furthermore, the study was designed to assess brand usage in research projects, compare common brands in terms of developer access to collected health data, and features to consider when deciding which brand to use in future research.MethodsWe searched for devices and brand names in six wearable device databases. For each brand, we identified additional devices on official brand websites. The search was limited to wrist-worn fitness wearables with accelerometers, for which we mapped brand, release year, and supported sensors relevant for fitness tracking. In addition, we conducted a Medical Literature Analysis and Retrieval System Online (MEDLINE) and ClinicalTrials search to determine brand usage in research projects. Finally, we investigated developer accessibility to the health data collected by identified brands.ResultsWe identified 423 unique devices from 132 different brands. Forty-seven percent of brands released only one device. Introduction of new brands peaked in 2014, and the highest number of new devices was introduced in 2015. Sensor support increased every year, and in addition to the accelerometer, a photoplethysmograph, for estimating heart rate, was the most common sensor. Out of the brands currently available, the five most often used in research projects are Fitbit, Garmin, Misfit, Apple, and Polar. Fitbit is used in twice as many validation studies as any other brands and is registered in ClinicalTrials studies 10 times as often as other brands.ConclusionsThe wearable landscape is in constant change. New devices and brands are released every year, promising improved measurements and user experience. At the same time, other brands disappear from the consumer market for various reasons. Advances in device quality offer new opportunities for research. However, only a few well-established brands are frequently used in research projects, and even less are thoroughly validated.

Both changes in the rates of out-of-hospital CHD deaths and hospitalization rates and the outcome of myocardial infarction (MI) with ST-segment elevation (STEMI) and non-ST-segment elevation (non-STEMI) will affect mortality. Editorial see p 8 Clinical Perspective on p 81It has been suggested that 45% to 75% of the decrease in deaths from CHD can be attributed to decreases in smoking, blood pressure, and cholesterol. [4][5][6][7][8] These studies based their estimates on ecological data or mathematical modeling of aggregate data. Few studies used individual person data, 9,10 and the studies were limited to population subgroups and did not study out-of-hospital CHD or subtypes of MI.We used individual person data from repeated surveys of a general population to study the rates of out-of-hospital CHD; the incidence, treatment, and outcome of hospitalized STEMI and non-STEMI; and the impact of changes in coronary risk factor levels during the years 1995 to 2010. Methods Study PopulationThe Tromsø Study is a population-based, prospective study of various health issues and chronic diseases. It consists of 6 surveys of both sexes conducted in the municipality of Tromsø, Norway, from Background-Few studies have used individual person data to study whether contemporary trends in the incidence of coronary heart disease are associated with changes in modifiable coronary risk factors. Methods and Results-We identified 29 582 healthy men and women ≥25 years of age who participated in 3 population surveys conducted between 1994 and 2008 in Tromsø, Norway. Age-and sex-adjusted incidence rates were calculated for coronary heart disease overall, out-of-hospital sudden death, and hospitalized ST-segment-elevation and non-STsegment-elevation myocardial infarction. We measured coronary risk factors at each survey and estimated the relationship between changes in risk factors and changes in incidence trends. A total of 1845 participants had an incident acute coronary heart disease event during 375 064 person-years of follow-up from 1994 to 2010. The age-and sex-adjusted incidence of total coronary heart disease decreased by 3% (95% confidence interval, 2.0-4.0; P<0.001) each year. This decline was driven by decreases in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in coronary risk factors accounted for 66% (95% confidence interval, 48-97; P<0.001) of the decline in total coronary heart disease. Favorable changes in cholesterol contributed 32% to the decline, whereas blood pressure, smoking, and physical activity each contributed 14%, 13%, and 9%, respectively. Conclusions-We observed a substantial decline in the incidence of coronary heart disease that was driven by reductions in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in modifiable coronary risk factors accounted for 66% of the decline in coronary heart disease events.

Objective: Because we found higher serum 25-hydroxyvitamin D (25(OH)D) levels among smokers than among non-smokers with analyses using an electrochemiluminescence immunoassay (ECLIA) from Roche, the purpose of the present study was to examine whether this difference between smokers and non-smokers was maintained using other serum 25(OH)D assays. Design: A cross-sectional population-based study on 6932 participants from the Tromsø study, 1994-1995, and one validation study comparing six different serum 25(OH)D assays in 53 non-smokers and 54 smokers were performed. Methods: The association between smoking, season and serum 25(OH)D as measured by ECLIA (Roche) was assessed in the population-based study using general linear models with multivariate adjustments. In the validation study, serum levels of 25(OH)D were analysed with liquid chromatography coupled with mass spectrometry assay from two different laboratories, RIA (DiaSorin), HPLC, RIA (IDS) and ECLIA (Roche). T-tests and linear mixed model analyses were performed to compare the serum 25(OH)D levels in smokers and non-smokers within and between the methods. Results: In the population-based study, the serum levels of 25(OH)D using the ECLIA method were 51.9, 53.2 and 72.0 nmol/l in never, former and current smokers (P!0.01). In the validation study, the serum concentration of 25(OH)D was 10.3 nmol/l higher in smokers than in non-smokers (P!0.01) using the ECLIA (Roche), while non-significantly lower serum levels of 25(OH)D were found in smokers using the other five methods. Conclusions: These two studies indicate that the ECLIA (Roche) overestimates serum 25(OH)D levels in smokers by unknown mechanisms. If confirmed, this might have clinical consequences, and the issue needs further exploration.

Russia has one of the highest rates of cardiovascular disease in the world. The International Project on Cardiovascular Disease in Russia (IPCDR) was set up to understand the reasons for this. A substantial component of this study was the Know Your Heart Study devoted to characterising the nature and causes of cardiovascular disease in Russia by conducting large cross-sectional surveys in two Russian cities Novosibirsk and Arkhangelsk. The study population was 4542 men and women aged 35-69 years recruited from the general population. Fieldwork took place between 2015-18. There were two study components: 1) a baseline interview to collect information on socio-demographic characteristics and cardiovascular risk factors, usually conducted at home, and 2) a comprehensive health check at a primary care clinic which included detailed examination of the cardiovascular system. In this paper we describe in detail the rationale for, design and conduct of these studies.

Trends in MI incidence differed by sex and age; in the age group 35-79 years a marked decrease was observed among men but an increase was observed among women, while no change was observed among older patients. MI severity and case fatality were clearly reduced for both sexes. These data suggest that the burden of CHD is shifting from middle-aged men toward middle-aged women and elderly patients.