What’s planned for Natsal-4?

The fourth Natsal survey will interview 10,000 people aged 15-59 years. Survey answers will be combined with information from biological samples (e.g. urine to test for sexually transmitted infections) and routinely collected data (e.g. health records). We will oversample (‘boost’) young people and people from black African and black Caribbean groups to allow more detailed statistical analyses of these groups.

 

Why has this age range been chosen?

The age range covered by Natsal has varied with each survey round. Although we wanted to include people over 59 years in Natsal-4, there were limited resources available and this was one of the difficult decisions we had to make. Natsal-3, which included people aged 16-74 years, focused on how people’s experiences vary throughout their lives.  Natsal-4 will focus more on young people, including oversampling 15-29 year olds so that we can better understand variation within this age group. This is because young people experience the greatest social and sexual changes and are more likely to experience adverse sexual health outcomes than other groups. For the first time in Natsal's history, we are planning a lower age limit of 15 years, since almost one-third of young people start having sex before 16. The survey development phase will consider the feasibility and ethics of this.

 

Why are you boosting the numbers from black Caribbean and black African backgrounds?  

Even with a sample size of around 10,000, we would not usually interview enough people from these groups to be able to analyse them separately. For this reason, in Natsal-3 we often had to group non-white ethnic groups together in analysis. Compared with people from other ethnic groups, people of black African ethnicity are disproportionately affected by HIV, and people of black Caribbean ethnicity are more likely to be diagnosed with some STIs or experience teenage pregnancy. This is why we have decided to boost the number of people we interview from these groups, so that they can be represented in the study’s findings. Unfortunately, this kind of boost sample is resource intensive, and so we have not been able to oversample other ethnic minority groups.

 

What biological samples will Natsal-4 collect and what will they be used for?

We will invite men and women to provide samples to test for sexually transmitted infections (STIs) (Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis, and for women only Human Papillomavirus (HPV)). These will be urine samples for men, and for women we will explore the feasibility of self-collected vulvo-vaginal swabs because these allow more accurate testing. We will assess the feasibility of returning clinically relevant results to participants using an online NHS results service. The biological samples will be stored in a biobank so that they can be used for future research. For example, the samples could be tested for the microbiota, which are the groups of microorganisms which inhabit our bodies: some are beneficial, but others may cause illness.

 

What routinely collected data will you use?

All Natsal-4 participants will be invited to consent to link their survey and biological data to their health records and other routinely-collected data. Linking these records creates opportunities to expand the range of data we have to answer complex research questions in ways that have not previously been possible.