Biomeasure Collection in Social Surveys - Challenges and Opportunities 1 |
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| Chair | Mr Matt Brown (Centre for Longitudinal Studies, UCL Institute of Education ) |
| Coordinator 1 | Dr Emily Gilbert (Centre for Longitudinal Studies, UCL Institute of Education) |
| Coordinator 2 | Ms Anne Conolly (Health and Biomedical team, NatCen Social Research) |
| Coordinator 3 | Dr Shaun Scholes (Research Department of Epidemiology and Public Health, University College London) |
The percentage of the UK population aged over 65 years is projected to rise from 17.7% in 2014 to 24.3% by 2039. Growing evidence from life course and historical cohort studies demonstrate that adult health, function and disease risk have their origins in early life experiences. A key data source in this investigation has been the MRC National Survey of Health and Development (NSHD), the oldest of the British birth cohort studies, whose study members reached age 70 in 2016.
In this paper we report on the 24th follow up that took place in 2015-16, when study members were invited to undertake an in-depth home visit conducted by a trained research nurse. The 90 minute home visit consisted of: recent medical history; blood collection; self-completion questionnaire (GHQ-28); reports of activities of daily living, time spent caring for others, household income and total value of assets; a repeat physical assessment including anthropometry, blood pressure, lung function and physical performance tests (specifically chair rises, standing balance, grip strength, walking speed and motor control); cognitive assessment (mental status test and repeat tests of verbal memory based on a word list task and processing speed based on a visual search task); and a physical activity monitor to measure vertical impact.
At this data collection phase, some measures were new, some had not been assessed since childhood and some were collected using novel methods. For example, we repeated a measure of finger tapping that was first recorded at age 15. We also included the Addenbrooke’s Cognitive Examination (ACEIII), a measure of mental status for the first time, which was collected using the touch screen capabilities of an iPad. The blood sample collection involved the nurse using a centrifuge in the home, in order to facilitate the analysis of inflammatory factors.
Participation in the home visit was high at 80% of the target sample. Data collection in older adults requires careful cohort management to maintain such a high participation rate, as well as an understanding of data capture techniques to engage participants and minimise burden. Importantly, long term follow up in birth cohort studies such as NSHD allows the investigation into how biological, behavioural, psychosocial and socioeconomic factors across life influence physical and mental ageing trajectories.
The inclusion of biomeasures within social surveys, and longitudinal surveys in particular, is becoming more common. Combining objective measurements of health with detailed information about lifestyles and behaviour collected over long periods of time offers enormous research potential.
The 1970 British Cohort Study (BCS70) is a longitudinal birth cohort study which began in 1970. Early sweeps of the study (at 5, 10 and 16) combined interviews, self-completion questionnaires and medical examinations but for the last 30 years all sweeps have been based on interviews and self-completion questionnaires. The 11th sweep of the study however, which began in 2016, when study members were 46, involves both an interview (50 minutes) and a detailed series of biomeasures : anthropometrical measurements, blood pressure, balance assessment, grip strength, placement of an accelerometer and the collection of blood for immediate analysis, future storage and DNA extraction.
Studies which combine an interview with biomeasures can be conducted in various ways. One model is that a field interviewer makes contact with the participant, conducts the interview and sets up an appointment for a follow-up visit from a nurse who will perform the biomeasures. The main disadvantage of this approach is that there will inevitably be some level of attrition between the interview and the biomeasures. Another model is to train field interviewers to collect biomeasures but there remain questions about whether the quality of data collected is comparable to that collected by a nurse, and some evidence suggests that field interviewers take longer to carry out such measures which can increase costs. In addition, field interviewers cannot take intravenous blood. Other studies invite participants to visit clinics, but this can be very costly in a large-scale national study. There is no consensus on the optimal strategy for combining a social survey with the collection of biomeasures.
BCS70 is using a new approach where nurses perform all of the data collection, including contacting participants and conducting the interview. The need to collect blood meant that the data collection strategy would need to include a nurse visit. Using the nurse for all other aspects of data collection was considered advantageous on the basis that it would maximise response to the biomeasures by reducing attrition between the interview and the nurse visit; would maximise the quality of the biomeasures collected and the efficiency of using one data collection agent would reduce costs. The main challenge was that although nurses have typically worked on research studies for many years they generally have little experience of contacting and tracing participants, maximising co-operation, and conducting interviews as these activities would normally be conducted by field interviewers meaning that considerable training was required. The impact of this approach on response rates and data quality was carefully piloted prior to the main stage of data collection.
This paper will evaluate the success of using nurses in this way and will outline the many other challenges and key lessons learned from adding a range of biomeasures to a long-established longitudinal study.
Surveys are extending the types of data they collect. An important new source is biological data such as blood or saliva collected from respondents. Nevertheless, this exciting new data source brings with it also a number of methodological issues. One of the most important ones is selection due to non-response and lack of consent to biological data collection. Our research aims to tackle this issue by looking at how nurses, respondents and areas influence 1) the likelihood that individuals will respond to the survey, 2) consent to biological data collection, and
3) the quality of the biological samples collected in two major British surveys: Understanding Society and English Longitudinal Study of Ageing. This research will inform how nurses can have an impact on selection and data quality and how to model these effects as part of substantive research. It will also inform possible ways in which data collection could minimize nurse effects.