Martijn de Groot

Measuring steps with the Fitbit activity tracker: an inter-device reliability study

Abstract Activity trackers like Fitbit are used for self-tracking of physical activity by an increasing number of individuals. Comparing physical activity scores with peers can contribute to the desired behavioural change. However, for meaningful social comparison a high inter-device reliability is paramount. This study aimed to determine the inter-device reliability of Fitbit activity trackers in measuring steps. Ten activity trackers (Fitbit Ultra) were worn by a single person (male, 46 years) during eight consecutive days. Inter-device reliability was assessed on three different levels of aggregation (minutes, hours, days) with various methods, including intra-class correlation coefficient (ICC), Bland-Altman plots, limits of agreement (LOA) and Mixed Model Analysis. Results showed that the inter-device reliability of the Fitbit in measuring steps is good at all levels of aggregation (minutes, hours, days), but especially when steps were measured per day. This implies that individuals can reliably compare their daily physical activity scores with peers.

The impact of gastrointestinal and genitourinary toxicity on health related quality of life among irradiated prostate cancer patients

PURPOSE To determine the impact of late radiation-induced toxicity on health-related quality of life (HRQoL) among patients with prostate cancer. PATIENTS AND METHODS The study sample was composed of 227 patients, treated with external beam radiotherapy. Common Terminology Criteria for Adverse Events version 3.0 were used to grade late genitourinary and gastrointestinal toxicity. The European Organization for Research and Treatment of Cancer Quality of life Questionnaire C30 (EORTC QLQ-C30) was used to assess HRQoL at baseline, and 6, 12 and 24 months after completion of radiotherapy. Statistical analysis was performed using a multivariate analysis of variance (MANOVA). RESULTS Urinary incontinence and rectal discomfort significantly affected HRQoL. The impact of urinary incontinence on HRQoL was most pronounced 6 months after radiotherapy and gradually decreased over time. The impact of rectal discomfort on HRQoL was predominant at 6 months after radiotherapy, decreased at 12 months and increased again 2 years after radiotherapy. No significant impact on HRQoL was observed for any of the other toxicity endpoints, or non-toxicity related factors such as hormonal therapy, radiotherapy technique or age. CONCLUSION Urinary incontinence and rectal discomfort have a significant impact on HRQoL. Prevention of these side effects may likely improve quality of life of prostate cancer patients after completion of treatment.

Do activity monitors increase physical activity in adults with overweight or obesity? A systematic review and meta-analysis

To systematically assess contemporary knowledge regarding behavioral physical activity interventions including an activity monitor (BPAI+) in adults with overweight or obesity.

Reliability and validity of ten consumer activity trackers depend on walking speed

Purpose To examine the test–retest reliability and validity of ten activity trackers for step counting at three different walking speeds. Methods Thirty-one healthy participants walked twice on a treadmill for 30 min while wearing 10 activity trackers (Polar Loop, Garmin Vivosmart, Fitbit Charge HR, Apple Watch Sport, Pebble Smartwatch, Samsung Gear S, Misfit Flash, Jawbone Up Move, Flyfit, and Moves). Participants walked three walking speeds for 10 min each; slow (3.2 km·h−1), average (4.8 km·h−1), and vigorous (6.4 km·h−1). To measure test–retest reliability, intraclass correlations (ICC) were determined between the first and second treadmill test. Validity was determined by comparing the trackers with the gold standard (hand counting), using mean differences, mean absolute percentage errors, and ICC. Statistical differences were calculated by paired-sample t tests, Wilcoxon signed-rank tests, and by constructing Bland–Altman plots. Results Test–retest reliability varied with ICC ranging from −0.02 to 0.97. Validity varied between trackers and different walking speeds with mean differences between the gold standard and activity trackers ranging from 0.0 to 26.4%. Most trackers showed relatively low ICC and broad limits of agreement of the Bland–Altman plots at the different speeds. For the slow walking speed, the Garmin Vivosmart and Fitbit Charge HR showed the most accurate results. The Garmin Vivosmart and Apple Watch Sport demonstrated the best accuracy at an average walking speed. For vigorous walking, the Apple Watch Sport, Pebble Smartwatch, and Samsung Gear S exhibited the most accurate results. Conclusion Test–retest reliability and validity of activity trackers depends on walking speed. In general, consumer activity trackers perform better at an average and vigorous walking speed than at a slower walking speed.

Key components in ehealth interventions combining self-tracking and persuasive ecoaching to promote a healthier lifestyle: a scoping review

Background The combination of self-tracking and persuasive eCoaching in automated interventions is a new and promising approach for healthy lifestyle management. Objective The aim of this study was to identify key components of self-tracking and persuasive eCoaching in automated healthy lifestyle interventions that contribute to their effectiveness on health outcomes, usability, and adherence. A secondary aim was to identify the way in which these key components should be designed to contribute to improved health outcomes, usability, and adherence. Methods The scoping review methodology proposed by Arskey and O’Malley was applied. Scopus, EMBASE, PsycINFO, and PubMed were searched for publications dated from January 1, 2013 to January 31, 2016 that included (1) self-tracking, (2) persuasive eCoaching, and (3) healthy lifestyle intervention. Results The search resulted in 32 publications, 17 of which provided results regarding the effect on health outcomes, 27 of which provided results regarding usability, and 13 of which provided results regarding adherence. Among the 32 publications, 27 described an intervention. The most commonly applied persuasive eCoaching components in the described interventions were personalization (n=24), suggestion (n=19), goal-setting (n=17), simulation (n=17), and reminders (n=15). As for self-tracking components, most interventions utilized an accelerometer to measure steps (n=11). Furthermore, the medium through which the user could access the intervention was usually a mobile phone (n=10). The following key components and their specific design seem to influence both health outcomes and usability in a positive way: reduction by setting short-term goals to eventually reach long-term goals, personalization of goals, praise messages, reminders to input self-tracking data into the technology, use of validity-tested devices, integration of self-tracking and persuasive eCoaching, and provision of face-to-face instructions during implementation. In addition, health outcomes or usability were not negatively affected when more effort was requested from participants to input data into the technology. The data extracted from the included publications provided limited ability to identify key components for adherence. However, one key component was identified for both usability and adherence, namely the provision of personalized content. Conclusions This scoping review provides a first overview of the key components in automated healthy lifestyle interventions combining self-tracking and persuasive eCoaching that can be utilized during the development of such interventions. Future studies should focus on the identification of key components for effects on adherence, as adherence is a prerequisite for an intervention to be effective.

Determinants for Sustained Use of an Activity Tracker: Observational Study

Background A lack of physical activity is considered to cause 6% of deaths globally. Feedback from wearables such as activity trackers has the potential to encourage daily physical activity. To date, little research is available on the natural development of adherence to activity trackers or on potential factors that predict which users manage to keep using their activity tracker during the first year (and thereby increasing the chance of healthy behavior change) and which users discontinue using their trackers after a short time. Objective The aim of this study was to identify the determinants for sustained use in the first year after purchase. Specifically, we look at the relative importance of demographic and socioeconomic, psychological, health-related, goal-related, technological, user experience–related, and social predictors of feedback device use. Furthermore, this study tests the effect of these predictors on physical activity. Methods A total of 711 participants from four urban areas in France received an activity tracker (Fitbit Zip) and gave permission to use their logged data. Participants filled out three Web-based questionnaires: at start, after 98 days, and after 232 days to measure the aforementioned determinants. Furthermore, for each participant, we collected activity data tracked by their Fitbit tracker for 320 days. We determined the relative importance of all included predictors by using Random Forest, a machine learning analysis technique. Results The data showed a slow exponential decay in Fitbit use, with 73.9% (526/711) of participants still tracking after 100 days and 16.0% (114/711) of participants tracking after 320 days. On average, participants used the tracker for 129 days. Most important reasons to quit tracking were technical issues such as empty batteries and broken trackers or lost trackers (21.5% of all Q3 respondents, 130/601). Random Forest analysis of predictors revealed that the most influential determinants were age, user experience–related factors, mobile phone type, household type, perceived effect of the Fitbit tracker, and goal-related factors. We explore the role of those predictors that show meaningful differences in the number of days the tracker was worn. Conclusions This study offers an overview of the natural development of the use of an activity tracker, as well as the relative importance of a range of determinants from literature. Decay is exponential but slower than may be expected from existing literature. Many factors have a small contribution to sustained use. The most important determinants are technical condition, age, user experience, and goal-related factors. This finding suggests that activity tracking is potentially beneficial for a broad range of target groups, but more attention should be paid to technical and user experience–related aspects of activity trackers.

Evidence-based practice for individuals or groups

The aim of applying science into practice is to deliver high-quality health care. Thinking about teaching the necessary accompanying skills, a distinction can be made between using evidence for individual patient care and using scientific knowledge for the development of protocols or guidelines for groups of patients or professionals. In this paper, these two ways of applying science into practice are being considered. We plea for explicating the differences between the individual patient and a group of patients or professionals when applying scientific knowledge in the decision-making process. The acknowledgment of these differences facilitates the teaching of the accompanying competences and different CanMEDS roles.

Lesion Detection Performance: Comparative Analysis of Low-Dose CT Data of the Chest on Two Hybrid Imaging Systems

Incidental findings on low-dose CT images obtained during hybrid imaging are an increasing phenomenon as CT technology advances. Understanding the diagnostic value of incidental findings along with the technical limitations is important when reporting image results and recommending follow-up, which may result in an additional radiation dose from further diagnostic imaging and an increase in patient anxiety. This study assessed lesions incidentally detected on CT images acquired for attenuation correction on two SPECT/CT systems. Methods: An anthropomorphic chest phantom containing simulated lesions of varying size and density was imaged on an Infinia Hawkeye 4 and a Symbia T6 using the low-dose CT settings applied for attenuation correction acquisitions in myocardial perfusion imaging. Twenty-two interpreters assessed 46 images from each SPECT/CT system (15 normal images and 31 abnormal images; 41 lesions). Data were evaluated using a jackknife alternative free-response receiver-operating-characteristic analysis (JAFROC). Results: JAFROC analysis showed a significant difference (P < 0.0001) in lesion detection, with the figures of merit being 0.599 (95% confidence interval, 0.568, 0.631) and 0.810 (95% confidence interval, 0.781, 0.839) for the Infinia Hawkeye 4 and Symbia T6, respectively. Lesion detection on the Infinia Hawkeye 4 was generally limited to larger, higher-density lesions. The Symbia T6 allowed improved detection rates for midsized lesions and some lower-density lesions. However, interpreters struggled to detect small (5 mm) lesions on both image sets, irrespective of density. Conclusion: Lesion detection is more reliable on low-dose CT images from the Symbia T6 than from the Infinia Hawkeye 4. This phantom-based study gives an indication of potential lesion detection in the clinical context as shown by two commonly used SPECT/CT systems, which may assist the clinician in determining whether further diagnostic imaging is justified.

The Values of Self-tracking and Persuasive eCoaching According to Employees and Human Resource Advisors for a Workplace Stress Management Application: A Qualitative Study

Self-tracking and automated persuasive eCoaching combined in a smartphone application may enhance stress management among employees at an early stage. For the application to be persuasive and create impact, we need to achieve a fit between the design and end-users’ and important stakeholders’ values. Semi-structured interviews were conducted among 8 employees and 8 human resource advisors to identify values of self-tracking, persuasive eCoaching, and preconditions (e.g., privacy and implementation) for a stress management application, using the value proposition design by Osterwalder et al. Results suggest essential features and functionalities that the application should possess. In general, respondents see potential in combining self-tracking and persuasive eCoaching for stress management via a smartphone application. Future design of the application should mainly focus on gaining awareness about the level of stress and causes of stress. In addition, the application should possess a positive approach besides solely the focus on negative aspects of stress.

Digitaal programma ‘leef gezond met diabetes’

SamenvattingZelf gegenereerde gezondheidsinformatie speelt steeds vaker een rol in het zorgproces. Deze trend komt enerzijds door het gemak waarmee mensen zelf met wearables en apps data over zichzelf kunnen verzamelen. Anderzijds wordt deze trend door zorgverleners en de overheid gestimuleerd om de klinische observaties met data uit de thuissituatie te kunnen verrijken, of omdat door reorganisatie of bezuiniging zelfmanagement is gewenst.1Ondanks positieve verwachtingen is er nog weinig onderzoek gedaan naar de implementatie en effectiviteit van zelfmeting en hieraan gerelateerde producten en diensten.AbstractDigital health program ‘living healthy with diabetes’ The interest in personal health data and self-monitoring in health care grows sustainably. Despite high expectations to innovate the health care system with digital health technology, little is still known about the implementation and effectiveness of digital health solutions in clinical practice. This article reports the pilot results of the development and implementation of a digital health program. The program is a combination of an online platform, activity tracker and smartphone application to support a positive lifestyle change for people with diabetes mellitus type 2. The service was developed by a public-private collaboration according to open innovation model.