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Methods of collecting biological data:

ESRC Research Methods Festival 2012. Methods of collecting biological data:. Considerations, challenges and implications. Passive smoking. Dietary salt levels. Vitamin D levels. Risk of CVD. Prevalence of STDs. Undiagnosed diabetes. Early kidney disease. Genetics.

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Methods of collecting biological data:

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  1. ESRC Research Methods Festival 2012 Methods of collecting biological data: Considerations, challenges and implications

  2. Passive smoking Dietary salt levels Vitamin D levels Risk of CVD Prevalence of STDs Undiagnosed diabetes Early kidney disease Genetics Why collect biological measures?

  3. Our experience of collecting biological measures 1.

  4. What have we collected? • Medical measures • Blood pressure • ECG • Lung function • Dental checks • Step tests (fitness) • Samples • Venous blood • Blood spots • Saliva • Urine samples • 24 hour urine • (Tracer water) • Hair • Measurements • Height and weight • Waist and hip • Arm circumference • Demi-span • Grip strength • Walking speed • Infant head circ. • Cognitive tests • Balance

  5. Who should collect what? • 2.

  6. Our traditional approach Standard interviewer visit + some measures (height and weight) Interviewer introduces nurse visit, may make appointment Nurse follow up visit at participant’s home to collect other measures • NatCen first used nurses in 1994 Health Survey for England • Requires a special panel of freelance nurses (we have around 150)

  7. Drawbacks of nurse follow ups: drop out % of interviewed who have nurse visit Survey HSE 2010 (adults) 71% (5,587 visits) Nurse HSE sample very similar to interview: Slightly fewer smokers and non-drinkers (esp. men). Little difference by Age; sex; BMI; general health; diet. Slightly more: Men with high BP NDNS Yr 3 74% (698 visits) ELSA wave 4 86% (8,218 visits) US (W2Y2 + W3Y1) 65% (4,409 visits)

  8. We have used interviewers to collect… • Height • Weight • Waist • Saliva sample • Urine samples • Timed walks • Infant length & head circumference • Grip strength • Cognitive tests • And recently developed protocols to extend interviewer biomarker collection to: • Blood pressure • (Scottish Health Survey) • Dried blood spots • (Scottish Health Survey from 2013)

  9. Drawbacks of nurse follow ups: logistics Paediatric phlebotomist Child fasting blood (35%) Blood to lab within 2 hours for spinning Adult fasting blood (69%) NDNS Interviewer visit Nurse visit (74%) Child 24 hr urine (74%) Adult 24 hr urine (80%) • NDNS requires clinics within two hours of each sample point • Specialist phlebotomists for some visits

  10. Use of clinics • Diet and Nutrition Survey of Infants and Young Children • Blood taking from 4 – 18 month olds, immediate spinning of blood • Feed special tracer water to these infants, specific dose • Skinfold measures • Decision to use clinic-based follow-up: • 20 clinics recruited (hospital/private), specific training for staff • 2 mobile vans with experienced staff (initially for people living far from a clinic)

  11. Clinic response Skinfold measure (99%) Blood (55%) Interviewer visit Clinic visit (44%) “Tracer water” taken (86%)

  12. Does it matter who takes the measurements or how they take it? • 3.

  13. …evidence from the Scottish Health Survey • Large scale survey monitoring the health of the Scottish population • Carried out 1995, 1998, 2003 and annually since 2008 • Collecting biomeasures using the traditional nurse model since 1995 • Switched to using field interviewers in 2012 • What impact, if any, will this move have on our ability to continue to monitor trends in…

  14. Mean waist measurement, 1995 - 2010 ? ?

  15. …waist measurements • move to a different (less invasive) protocol

  16. Blood pressure level, 2008-2010 ? ?

  17. …blood pressure • Protocol unchanged • Concerns about non-medically trained interviewers collecting it • Interest in whether “white coat syndrome” extends to nurses

  18. Validation study objectives were… • To establish the degree of correlation between interview and nurse measurements • Generate calibration equations that allow for SHeS statistics to be ‘converted’

  19. How did we do it? • Paired up trained field interviewers and survey nurses (15 pairs) • Pairs visited respondent in own home, taking turns to take BP readings & waist measurements • Purposive sample – oversampled aged 55+ • 300 paired interviews carried out (Mar-May 2012)

  20. Factors considered • Order of interviews was randomised • Carried out consecutively • Partner not in the home at time of interview • Same blood pressure machine used • Participant told whether an interviewer/nurse • Results from 1st visit not given to participant

  21. Interview content • Interviewer visit • Blood Pressure • Waist measurement • Nurse visit • Blood pressure • Waist measurement (own protocol) • Waist measurement (interviewer protocol)

  22. So did it matter who took the measurements & how?

  23. Biomarkers – things to consider • It is possible to collect a range of biological measures within a survey based study, but it is important to consider how: • Who will collect (interviewer, nurse, clinic, self): • Complexity of measure, protocol, acceptability, analysis requirements, target population • Ethical considerations • Training is vital – quality is important! • Equipment: ease of use, portability, durability • Labs – work with them to agree protocols, check quality! • Data analysis – can be a minefield.

  24. Thank you If you want further information or would like to contact us • Lisa Rutherford • Research Director • T. +44 (0)131 221 2555 • E. lisa.rutherford@scotcen.org.uk • Visit us online, natcen.ac.uk

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