Most chlamydia testing now takes place outside genitourinary medicine (GUM) clinics. Although the majority of those tested in other settings are less likely to report risky sexual behaviour, a substantial minority do and some patients with chlamydia infection are missing out on HIV tests, NATSAL-3 has shown.

The investigators compared characteristics of those tested for chlamydia in GUM, general practice and other settings using data from NATSAL-3, a British probability sample survey carried out in 2010-2012.

Survey participants were aged 16-44 years with at least one sexual partner in the past year. Of a total of 8,397 participants (4,992 women) 27% of women and 17% of men reported having a chlamydia test in the past year. This was more common in those aged 16-24 (55% of women and 36% of men) which is the age group eligible for the national chlamydia screening programme in England.

Of those who had been tested, 28% of women and 41% of men had been tested in GUM clinics; 41% and 27% of women and men respectively in general practice, and 31% and 38% in other non-GUM settings including: university, schools, family planning clinics, antenatal clinics and termination of pregnancy services.

Women who tested for chlamydia in general practice tended to be older, living with a partner, and living in rural areas compared with those tested in GUM clinics. Men were just as likely to test in general practice and in GUM clinics for chlamydia.

People tested in general practice or other settings were generally less likely to report risk behaviours for STIs than those tested in GUM clinics. However,  11% of women tested in general practice and 13% in other non-GUM settings reported unsafe sex i.e. at least two partners in the past year and with no condom use. For men, the figures were 7% of those tested in general practice and 10% of those tested in other settings.

Of the women reporting unsafe sex, 85% of those tested in general practice and 73% tested in other settings had not attended a GUM clinic in the past year. For men, the figures were 80% who were tested in general practice or non-GUM settings.

Of the participants with at least one sexual partner in the past year, 4% of women (n = 285)  and 4%  of men (n = 178) reported a diagnosis of chlamydia in the past five years. Of these, 58% of women and 77% of men were treated in GUM; 27% of women and 18% of men were treated in general practice.

Of those who were treated for chlamydia in the past five years, 66% of women and 56% of men reported being tested for HIV at the same time; this was less common in those treated in general practice and other locations compared with GUM clinics (55% vs 74%). Of those women tested for chlamydia in non-GUM settings, around half had tested for HIV in a sexual health check and 29% because of pregnancy, very few because they were advised to by a doctor.

Most chlamydia testing occurred in non-GUM settings, in particular general practice, where people tended to have fewer risk behaviours. However, general practice was a setting for at least a quarter of men and women for chlamydia treatment, some of whom were not tested for HIV even though they reported sexual risk behaviour.

There is a clear contribution to STI control from general practice, we need to ensure that we use opportunities to test for STIs including HIV, and treat where appropriate.

Dr Richard Ma