London School of Hygiene & Tropical Medicine

New results from the third National Survey of Sexual Attitudes and Lifestyles (Natsal), published in The Lancet, provide a picture of sexually transmitted infection (STI) prevalence and testing, uptake of sexual health interventions and service use, and risk behaviours in Britain.

In the decade since the last Natsal survey, of several strategies aimed at improving sexual health in Britain, three have been STI-specific interventions: the English National Chlamydia Screening Programme (NCSP); the UK HPV immunisation programme; and increasing HIV testing in target groups [1].

Researchers from UCL (University College London), the London School of Hygiene & Tropical Medicine, NatCen Social Research, and Public Health England interviewed nearly 9,000 participants aged 16-44 about their sexual lifestyles and uptake of STI services and interventions. They collected urine samples from over 4,500 16-44 year olds, and tested these for chlamydia, gonorrhoea, high-risk human papillomavirus (HR-HPV), and HIV.

HR-HPV (the virus that causes cervical and other cancers) was the most prevalent infection, detected in 16% of women overall. Around one in a hundred people aged 16-44 had chlamydia, but this was higher in those aged 16-24 (prevalence of 3.1 % and 2.3% in women and men, respectively). Both chlamydia and HPV prevalence were higher in people who had sex with more partners without a condom, but these STIs were also found in people with only one partner in the last year.

The population prevalence of gonorrhoea in those aged 16-44 was less than 1 in 1000 (<0.1%) and for HIV it was slightly higher (0.1% in women; 0.2% in men). While both these infections were restricted to those with known high risk factors, they have different implications for individuals, partners, control measures, and service provision.

Exploring the reach of the HPV catch-up immunisation programme, the survey found over 60% of eligible women said that they completed the vaccination course. Encouragingly, the study found that prevalence of HR-HPV in women aged 18-20 years has fallen since the previous survey – down to 5.8% from 11.3%, an early effect of the immunisation programme.

Among 16-24 year olds, 54% of women and 35% of men had been tested for chlamydia in the past year. Testing rates were higher in England compared to Scotland or Wales. Those with more partners in the past year were more likely to have tested for chlamydia.

The proportion of participants reporting an HIV test in the past five years has increased significantly to 28% in women and 17% in men, up from 8.7% in women and 9.2% in men for the previous survey. Appropriately, HIV testing was higher in those with more partners and in those targeted for testing, including men who have sex with men.

Attendance at sexual health clinics has also increased since the previous survey, rising from 6.7% to 21% in women, and from 7.7% to 20% in men. Clinic attendance is highest in younger people, those with higher numbers of partners and in women from the most deprived areas.

The study was funded by the Medical Research Council and The Wellcome Trust, with additional funding from the Economic & Social Research Council and the Department of Health.

• Pam Sonnenberg, Soazig Clifton, Simon Beddows, Nigel Field, Kate Soldan, Clare Tanton, Catherine H Mercer, Filomeno Coelho da Silva, Sarah Alexander, Andrew J Copas, Andrew Phelps, Bob Erens, Philip Prah, Wendy Macdowall, Kaye Wellings, Catherine A Ison, Anne M Johnson. Prevalence, risk factors, and uptake of interventions for sexually transmitted infections in Britain: findings from the National Surveys of Sexual Attitudes and Lifestyles (Natsal). The Lancet. DOI: 10.1016/S0140-6736(13)61947-9