What is involved in taking part in cohort studies?

Cohort studies often require participants to answer questions about health or social wellbeing and to undertake some kind of physical examination or tests, depending on the purpose of the study.

Some cohort studies are also linked to patient medical records, so test results and information about health can be taken from these records for use in the research without the participant having to provide the information themselves.

How often do people take part in activities?

Usually there are some questions, tests and measurements that people complete when they first join a cohort study. This is sometimes called a baseline assessment. These may involve physical measurements (like height and weight), giving samples, or having scans. Sometimes there is also behavioural and cognitive testing, reasoning or memory tests.

After a set time period, people may be invited to return for tests again. Some medical cohort studies have clear timespans when participants will be seen again, such as every two, five or ten years. After having a transient ischaemic attack (TIA, a ‘mini stroke’) and joining a cohort study, Alan Y had follow-up tests three times in the first year and then at five years and ten years.

Alan Z had an appointment every year for three years where he went to his doctor’s surgery for tests that lasted about half an hour.

Age at interview 86

Gender Male

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Since being diagnosed with motor neurone disease (MND), Ian has been going for a day of tests with the research study team every six months. He is impressed by how the researchers made him feel part of the team that are researching the issue.

Age at interview 54

Gender Male

Age at diagnosis 51

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Keith had a series of tests when he first started a study. He didn’t have anything for two years and then he was called again for an absolutely massive day of tests.

Age at interview 68

Gender Male

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Taking part in birth cohort studies, which may last a person’s lifetime, can be more irregular due to the availability of funding. There may be a flurry of activities and then nothing for a while. Some people who took part in birth cohort studies remembered taking part in height and weight measurements and reasoning tests at primary school but since then have only completed questionnaires when they have come through the post or online.

Jess and Anne presumed the team had access to their medical records and there had been no need to follow them up to complete other activities. Others had been invited to take part in medical tests or cognitive tests (about thinking, reasoning and memory).

Ronald recalls having a physical examination in primary school for the birth cohort study. He hasn’t been asked to do anything else since.

Age at interview 66

Gender Male

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In addition, participants may occasionally be asked if they would be willing to provide some information or samples for sub-studies linked to the cohort study. Sub-studies are additional projects which are related to but also separate to the main study, and they can involve collecting extra data and/or looking at additional topics.

What types of activities do participants do?

Depending on the subject and purpose of the study, people we talked to said they had taken part in a variety of activities. These included:

  • Physical measurements, medical tests and giving samples;

These can include height, weight, blood pressure readings, eye tests, MRI scans or CT scans, ultrasounds, electrocardiograms, DEXA scans (bone density), and giving various samples (for example blood, urine, hair, saliva, and placenta tissue). Nadera was happy to have a DEXA scan because “it’s interesting for me to know as well what’s happening inside of me.” Salma and her children gave samples of blood and urine and she completed a questionnaire in hospital with the study staff. Her children also wore activity monitors on their waist for a week. Lucy remembers every few years having to undress so that the healthcare professionals in her study could document and photograph the moles on her body.

Mr S and his wife were asked to provide saliva tests when they joined a parent and baby study. They were given equipment to take samples with at home.

Age at interview 35

Gender Male

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Luke is part of a twins study and every four years he and his twin spend a day at the hospital clinic having medical tests. He describes it as a very medical experience.

Age at interview 35

Gender Male

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Barbara’s participation varies; sometimes she fills in a questionnaire and other times they ask her to have physical and cognitive ability tests.

Age at interview 73

Gender Female

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Douglas has blood samples taken for the research he is in. He has been told he is difficult to take blood samples from but he disagrees and says it is about the skills of the professional.

Age at interview 70

Gender Male

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Some people took part in more invasive physical medical tests. Gareth had samples of blood and fat taken from his thigh and stomach. He was worried that it would be painful and it would bruise which it did, but only for a week. Although lumbar punctures are not normally painful, Roland and Ian chose not to take part in this test, which did not affect their overall involvement in the cohort study.

  • Completing psychological or cognitive ability tests;

These can include memory tests, reasoning, personality tests, meanings of words, matching patterns, and IQ tests. Linda remembers taking part in verbal reasoning tests at primary school and being given a prize of “exotic dried fruit.”

Margaret had memory tests for a birth cohort study where a nurse came to her house.

Age at interview 73

Gender Female

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Malcolm had a cognitive ability test which lasted about an hour.

Age at interview 75

Gender Male

Age at diagnosis 48

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Jade remembers completing tests once a year for a twins study and filling in surveys which they did at home. Her parents also filled in questionnaires.

Age at interview 25

Gender Female

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  • Completing questionnaires or diaries;

There were many different topics that questionnaires could ask about, including diet, exercise, smoking, leisure activities, occupation, education, family circumstances, and mental health (emotions and mood). Teresa had also been asked to keep a diary for the research about her diet. When Nadera joined a parent and baby study, she answered questionnaires for each of her three children about “feeding patterns and then data like height, weight, eating pattern, sleeping pattern I believe, activity.” Some people emphasised that the wording of the questions in questionnaires and discussions with the researchers was important.

Eisha filled in questionnaires about her diet and emotional wellbeing for a parent and baby cohort study she took part in.

Age at interview 32

Gender Female

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Housework and gardening weren’t recognised as physical activities when James first completed a questionnaire about his lifestyle.

Age at interview 76

Gender Male

Age at diagnosis 66

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Mr S thinks some questions in questionnaires are personal and people may be reluctant to answer them. He encourages researchers to carefully phrase their questions and explain why they want to know.

Age at interview 35

Gender Male

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Barbara says the questionnaires she completes are constructed well.

Age at interview 73

Gender Female

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Sometimes questionnaires were sent directly to participants. Gill said she found it interesting to fill in the questionnaire every two years because each time they were on different topics. When it arrived in the post, she thought ”Oh this is interesting. I wonder what questions they’ll be asking this year?”

Other times, there was a health professional who asked the questions or took the participant through the questionnaire. Salma sat with a health professional who filled in a questionnaire on an iPad. Anthony, who was involved in a study for 15 years after he had his knees replaced, used to go to the hospital to answer questions: “mainly it was just how flexible the knees were, how I was able to do long walks and just general exercise that I was happy that the knees they gave me were performing as they should be.” George went every two months to see the research study team where they ask him questions about his stroke and how he is getting on.

Barbara likes having the paper version of the questionnaire to fill in. She can reflect more on her answers and make changes more easily.

Age at interview 73

Gender Female

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The activities Teresa has been asked to do varied over the timespan of the birth cohort. She remembers the questionnaires were sometimes long and detailed.

Gender Female

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Where do activities take place?

People we talked to had completed cohort study activities in various places: in a hospital, at a GP surgery, at a university, or at home.

Sometimes people said the researcher was present while they completed their test. Keith was glad he could complete his reasoning tests alone in a booth. Gareth felt happy there were only three researchers in the room while he had his tests; he says, “I certainly wouldn’t have been happy if there’d been a constant stream of different people wandering in.”

For some studies, researchers visited people in their homes. Margaret Ann recalls that someone from the study came to her home and took her height and weight measurements and asked her questions about her health and diet. One of the times the nurse visited Teresa, without warning she threw a box of matches at her to check her reflexes.

Margaret recalls having tests at school and then, over the course of the study, filling in questionnaires and a nurse researcher visiting her at home to do physical tests.

Age at interview 73

Gender Female

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A researcher came to Brian’s house for an hour to carry out physical and memory tests for the birth cohort study. One time, he had to stand on one leg and stand up on a chair.

Age at interview 73

Gender Male

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Anthony, John, Keith and Emily were issued with medical equipment to use at home: Anthony wore a heart monitor and a Fitbit for a week to record physical activity. John, Keith and Emily were issued with a blood pressure monitor to take blood pressure readings at home.

Emily was issued with a blood pressure monitor connected to a mobile phone. She took her blood pressure three times a day and the results were sent back to the hospital.

Age at interview 68

Gender Female

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Anthony didn’t expect to receive any results based on the readings of a heart monitor and Fitbit. He thinks the researchers would have told him if there were any concerns.

Age at interview 76

Gender Male

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