Non-Consent to a Wrist-Worn Accelerometer in Older Adults: The Role of Socio-Demographic, Behavioural and Health Factors

Behavioural and Health Factors. PLoS ONE 9(10): e110816. doi:10.1371/journal.pone.0110816 Non-Consent to a Wrist-Worn Accelerometer in Older Adults: The Role of Socio-Demographic, Behavioural and Health Factors Se verine Sabia 0 Maliheh Hassani 0 Mika Kivimaki 0 Alexis Elbaz 0 Martin Shipley 0 Archana Singh-Manoux 0 Hemachandra Reddy, Texas Tech University Health Science Centers, United States of America 0 1 Department of Epidemiology & Public Health, University College London , London , United Kingdom , 2 INSERM, U1018 , Centre for Research in Epidemiology and Population Health , Villejuif , France , 3 University Paris 11, Villejuif, France, 4 University Versailles St-Quentin, Boulogne-Billancourt, France, 5 Centre de Ge rontologie, Ho pital Ste Pe rine, AP-HP , Paris , France Background: Accelerometers, initially waist-worn but increasingly wrist-worn, are used to assess physical activity free from reporting-bias. However, its acceptability by study participants is unclear. Our objective is to assess factors associated with non-consent to a wrist-mounted accelerometer in older adults. Methods: Data are from 4880 Whitehall II study participants (1328 women, age range = 60-83), requested to wear a wristworn accelerometer 24 h every day for 9 days in 2012/13. Sociodemographic, behavioral, and health-related factors were assessed by questionnaire and weight, height, blood pressure, cognitive and motor function were measured during a clinical examination. Results: 210 participants had contraindications and 388 (8.3%) of the remaining 4670 participants did not consent. Women, participants reporting less physical activity and less favorable general health were more likely not to consent. Among the clinical measures, cognitive impairment (Odds Ratio = 2.21, 95% confidence interval: 1.22-4.00) and slow walking speed (Odds Ratio = 1.38, 95% confidence interval: 1.02-1.86) were associated with higher odds of non-consent. Conclusions: The rate of non-consent in our study of older adults was low. However, key markers of poor health at older ages were associated with non-consent, suggesting some selection bias in the accelerometer data. - Funding: This work was supported by the US National Institutes of Health (R01AG013196 to ASM; R01AG034454 to ASM and MK, R01HL036310 to MK) and the UK Medical Research Council (K013351 to MK). MJS is partly supported by the British Heart Foundation. MK is supported by a professorial fellowship from the Economic and Social Research Council. The study sponsor had no role in study design, collection, analysis, and interpretation of data, writing the report, and decision to submit the report for publication. Competing Interests: The authors have declared that no competing interests exist. Physical activity is seen to be key to successful aging, [1] reducing risk of a range of chronic diseases [2] and cognitive [3] and physical [4] impairment. However, the true effect of physical activity remains unclear as much of the research comes from studies where physical activity is self-reported, making associations subject to reporting biases. The correlation between objectively measured physical activity (e.g. accelerometry, doubly labelled water, heart rate monitor) and activity measured via questionnaire is typically low to moderate [5] and may be even lower in older adults. [69] Questionnaire-assessed measurements are prone to reporting bias, for example, due to social desirability or inaccurate recall, [5] and to measurement error since questionnaires include a limited number of items and do not capture the full range of physical activity undertaken over several days. [10] The low-tomoderate correlation between questionnaire and objective measures of physical activity, along with accelerometers becoming more affordable, is leading to an increasing use of accelerometers to measure physical activity, [1120] including in studies on older adults. [11,12,20] Accelerometry is a measure of one part of the body with inferences that apply to the whole body. It has the advantage of being free from reporting bias. In most previous studies, accelerometers are worn on the waist but moderate acceptance rate has led increasingly to the use of wrist-worn accelerometers. [21] However, its acceptability, especially among older persons, is unclear. [22,23] Some studies have investigated the characteristics associated with non-wear time of waist-mounted accelerometers among those consenting to wear the device [2426] but less is known about factors associated with non-consent. [26] Our objective was to assess non-consent to a wrist-worn accelerometer in older adults and examine the role of socio-demographic, behavioural, anthropometric, and health-related factors. Study population Data are drawn from the Whitehall II cohort study, established in 1985/88 on 10,308 individuals (67% men), aged 3555 years. [27] Participants gave written consent to participate in the study and the University College London ethics committee approved the study. Study design consists of a clinical examination and a selfadministered questionnaire. Since inception, socio-demographic, behavioural, and health-related factors, including self-reported physical activity via questionnaire, have been assessed approximately every five years (1985/88, 1991/93, 1997/99, 2002/04, 2007/09 and 2012/13). Accelerometer-assessed physical activity Accelerometry was introduced the study at the 2012/13 clinical assessment for participants seen at the central London clinic and among those screened at home, living in the South-Eastern regions of England. A wrist-worn triaxial accelerometer (GeneActiv, Activinsights Ltd, Cambs, United Kingdom) was used, participants were asked to wear the waterproof accelerometer on their nondominant wrist, non-stop for 9 consecutive (24-hour) days. They were also asked to complete a diary alongside wearing the accelerometer to report overnight sleep periods (falling asleep/ standing up times), cycling and non-wear time. Among the 4880 participants who were offered the accelerometer, 388 did not consent and 210 had contraindications (allergies to metal or plastic (N = 40), travelling abroad (N = 168), other reasons (N = 2, strap too short and cognitive impairment)) and were not given the accelerometer. Socio-demographic factors Demographic variables included in the analysis were age, sex, ethnicity (White, non-White) and marital status (married/cohabiting, other). Socioeconomic status (SES) measures included education and occupational position at 50 years. Education was defined as the highest qualification on leaving full-time education, categorized as university degree, higher secondary school, lower secondary school, and lower primary school or below. Occupational position was defined using the British civil service grade of employment and categorised as high (administrative), intermediate (professional or executive) and low (clerical or support grades). This measure in th (...truncated)