NATSAL: Surveying sex in the British population
The first survey - NATSAL I in 1990 - was funded by the Wellcome Trust, and a second study, NATSAL II, was carried out in 2000 with Medical Research council (MRC) funding. The studies have provided vital data for scientists, clinicians and policy makers on sexual health and risk taking in sexual behaviours, and regularly inform sex education policy and public health planning. In 2008, the Wellcome Trust and the MRC announced funding for NATSAL III in 2010.
Background
Understanding trends in sexual behaviour is essential for public health education and the control of sexually transmitted diseases. During the 20th century, however, researchers in the field met with resistance and hostility: Alfred Kinsey working in the 1940s and 1950s was threatened with dismissal for his pioneering studies of sexual behaviour. As a consequence, relatively little research in this area was carried out.
The rise of AIDS in the 1980s meant that data on sexual behaviour and attitudes were urgently needed for the prevention and prediction of HIV transmission. In 1987, epidemiologist Anne Johnson at University College London (now Professor of Infectious Disease Epidemiology, Head of the Division of Population Health, and Co-director of the Institute for Global Health at UCL) and colleagues designed the first large-scale study of sexual lifestyles and attitudes in a random sample of the population - the National Surveys of Sexual Attitudes and Lifestyles (NATSAL).
The project received preliminary approval for public money. But in 1989, the UK Government vetoed the award, regarding the survey as an invasion of people's privacy and unlikely to produce valid results. At this point the Wellcome Trust stepped in and, within two months, awarded the funds to make NATSAL possible. As a consequence the survey was delayed by only a few months.
The following years saw rapid social development, and increases in sexually transmitted diseases and teenage pregnancies. By the end of the 1990s the need for an update was clear. NATSAL II was conducted in 2000, funded by the MRC. NATSAL III will take place in 2010 with financial backing from the Trust and the MRC.
Advance
The NATSAL studies describe patterns of sexual behaviour in the UK population and link these to sexual and reproductive health and demography. Data from the studies can identify the extent of specific risk behaviours within the population, allowing the efficient targeting of health education.
NATSAL I was the first study of sexual behaviour to survey the general population rather than volunteers and found, for example, a strong relationship between the age of onset of sex and sexual health. The second study was designed to generate data compatible with NATSAL I (as has NATSAL III), and revealed worrying trends such as increases in risk taking in sexual behaviours between 1990 and 2000.
How it's making a difference
Data from the NATSAL studies are a key resource for scientists, clinicians and policy makers, and regularly inform policy making on sexual and reproductive health. The original Trust-funded survey of 1990 allowed projections of the spread of HIV and linked the incidence of sexually transmitted infections to high-risk practices.
The studies have been used extensively in Department of Health strategic documents and policy making. For example, NATSAL provided the first population-based estimates of asymptomatic Chlamydia trachomatis infection, guiding the national screening strategy on where and how to best focus its resources.
The analysis of NATSAL data continues to inform programmes of sex education. A key question is why people continue to pursue high-risk activities in spite of the dangers being common knowledge. To help to inform sexual health communication campaigns, researchers have combined NATSAL data on behaviour with data on attitudes to identify the barriers to practising risk reduction. The survey has also uncovered a mismatch between the high prevalence of problems with sexual function and the low level of help sought, which again can be used in public information campaigns.
Next steps
In Britain, cases of sexually transmitted infections such as genital warts, Chlamydia, syphilis and HIV continue to increase. Such trends and changes in demography all mean that a new survey is now needed. The joint funding of NATSAL III by the Wellcome Trust and the MRC was announced in October 2008 and will take place in 2010 after a development phase.
Scientific advances will allow improved methodology and more biological measures to be included. For example, a new, non-invasive measure of testosterone levels in saliva will be developed to test for links between testosterone levels and sexual activity in men and women. The new study will also include a broader age range - from 16 to 74 years - so that changes in sexual lifestyle through life can be studied, and the relationship between sexual wellbeing and physical health understood.
By combining data from all three surveys the multidisciplinary team - from UCL, the national Centre for Social Research, the London School of Hygiene and Tropical Medicine, the University of Manchester and the Health Protection Agency - will be able to analyse changes in behaviour with age and through different generations. They also plan to evaluate the successes and failures of strategies for improving sexual health since 1990. Why, for example, in spite of raised awareness among policy makers and investment in sexual health programmes, has the number of unwanted pregnancies and the incidence of sexually transmitted infections and HIV remained high? The NATSAL studies will therefore provide a unique source of information about the sexual attitudes and lifestyles of people born from the 1930s to the 1990s.
References
- Johnson AM et al. The National Survey of Sexual Attitudes and Lifestyles. Oxford: Blackwell Scientific Press; 1994.
- Fenton KA et al. Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection. Lancet 2001;358:1851-4.
- Johnson AM et al. Sexual behaviour in Britain: partnerships, practices, and HIV risk behaviours. Lancet 2001;358:1835-42.
- Mercer CH et al. Sexual function problems and help seeking behaviour in Britain: national probability sample survey. BMJ 2003;327:426-7.
- Fenton KA et al. Sexual behaviour in Britain: ethnic variations in high-risk behaviour and STI acquisition risk. Lancet 2005;365:1246-55.