group on Chlamydia trachomatis was set up to advise on the issues associated ... partner or with more than one partner in the past year were. SHORT REPORT.
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SHORT REPORT
Performance of the recommendations of a British advisory group for screening for chlamydia in a sample of women in general practice V Verhoeven, D Avonts, A Meheus, M Ieven, H Goossens, P Van Royen ................................................................................................... J Med Screen 2003;10 :14–15 See end of article for authors’ afliations
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Correspondence to: Dr V Verhoeven, Department of General Practice, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; veronique.verhoeven @ua.ac.be Accepted for publication 24 January 2003
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In this study the performance of the guidelines produced by the British Chief Medical Ofcer’s expert advisory group for selective screening for Chlamydia trachomatis was evaluated. The guidelines were applied to a sample of 777 women in general practice in Antwerp, Belgium. The accuracy of the screening/testing recommendations was suboptimal. The model detected 90% of infections but failed to identify a high-risk population; the population to be screened was reduced by only 21%. The focus on young age as the most important determinant for screening was not appropriate. More attention should be paid to risky sexual behaviour.
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nfection with Chlamydia trachomatis is the most common curable sexually transmitted disease in developed countries. High prevalence rates are found in various settings in Europe, including in general practice.1 Chlamydial infection is largely asymptomatic but complications such as pelvic inammatory disease, ectopic pregnancy and infertility are common. The health care costs of chlamydial disease are high and its effect on people’s lives is profound. The burden of undiagnosed infection in the population indicates that screening should be considered. In Britain the Chief Medical Of cer’s expert advisory group on Chlamydia trachomatis was set up to advise on the issues associated with screening for chlamydia. The group evaluated the evidence for screening and made recommendations concerning the circumstances in which testing should be offered (Box 1).2 We investigated the performance of those guidelines in a sample of women in general practice in Belgium.
Box 1
The advisory group’s recommendations for screening/testing women for chlamydia Opportunistic screening should be offered to: r
Asymptomatic sexually active women aged under 25, especially teenagers (priority). r
Asymptomatic women aged over 25 who have had a new sexual partner or have had two or more partners in a year (lower priority). r
All attenders at genitourinary medicine clinics. r
All women seeking termination of pregnancy. Testing should be offered to the following symptomatic groups, regardless of age or any other factors: r
Women with acute pelvic inammatory disease. r
Women with mucopurulent cervicitis. r
Women with lower abdominal pain. r
Women with vaginal discharge. r
Women with postcoital or intermenstrual bleeding.
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METHODS The study was carried out in 32 general practices in Antwerp, Belgium. Sexually active women visiting their general practitioner (GP) for routine gynaecological care (mostly contraceptive pill prescription or a Papanicolaou smear) were offered screening for chlamydia. Those who agreed to participate delivered a self-taken vaginal sample and lled in a questionnaire which covered demographic variables, urogenital symptoms, sexual history and sexual behaviour. Details of the patients’ characteristics are reported elsewhere.3 Samples were tested for the presence of chlamydial DNA by means of a ligase chain reaction assay, and positives were con rmed by two other ampli cation assays – polymerase chain reaction and strand displacement amplication. Risk factors for chlamydial infection were identi ed by multivariate logistic regression analysis.3 Test results were reported to the GPs, who counselled and treated infected patients and their partners.
RESULTS Seventy- ve per cent of all distributed screening packages were returned by patients (there were 777 participants, aged 15–40 years). Overall, 39 women were infected, a prevalence of chlamydial infection of 5.0% (95% CI: 3.5% to 6.5%). Prevalence according to age was 4.8% in women aged 14–19 (6/126), 5.4% in women aged 20–24 (14/260), 5.8% in women aged 25–30 (14/242) and 3.4% in women aged 31–40 (5/149). The sensitivity of the expert group’s various screening recommendations when applied to our population is shown in Table 1. The “full model” would detect a large majority of infections but in this strategy almost the whole population (79%) needs to be screened. If only women with a new partner or with more than one partner in the past year were www.jmedscreen.com
Screening for chlamydia
Table 1
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Performance of the expert group’s guidelines
Determinant for screening
Number of infections detected (sensitivity) (n=39)
Number of patients to be screened (proportion of total population) (n=777)
Prevalence in screened population (%)
Age 1 partner or recent change in partner Full screening model (see Box 1)* >1 partner or recent change in partner
20 34 35 28
386 505 614 330
5.2 6.7 5.7 8.5
(51%) (87%) (90%) (72%)
(50%) (65%) (79%) (42%)
*Data on vaginal discharge, intermenstrual or postcoital bleeding and lower abdominal pain were available from the questionnaire.
to be tested, this would greatly reduce the population to be screened and would detect nearly three-quarters of infections.
DISCUSSION In a sample of women in general practice, the British advisory group’s guidelines would lead to the detection of a reasonable proportion of infections but the screening/testing criteria are nonetheless suboptimal. In particular, testing every woman who has some sort of genital complaint would incorrectly classify too many women as being at risk of infection. Such a screening programme would be unnecessarily expensive and too demanding in terms of the workload of health care providers. The latter probably would limit the success of any control programme. An issue that deserves reconsideration is the priority given to teenagers and women aged under 25 years. This recommendation is based on high prevalences in these age categories, found in studies in genitourinary medicine clinics in the UK and in different settings in the US. Only one study with ampli cation diagnostics in general practice, with relatively few young participants, is mentioned in the report. However, these observations are not con rmed by recent European prevalence studies in the general population and in general practice settings. These studies found a rather weak association of chlamydia with young age4,5 and even a low prevalence in teenagers.6 A peak prevalence in women in their 20s7 and a declining but still substantial prevalence in women aged 25–304,5,7 were also observed. Because chlamydia can affect reproductive health, young women have been seen as the chief bene ciaries of screening but, as many women choose to become pregnant at an older age, young age should not be the most important reason for offering screening. The relative importance of age and other sociodemographic risk factors depends on the clinical setting and is subject to changes in social structures. Risky sexual behaviour is more dif cult to assess as a criterion for
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screening but is probably the best predictor of chlamydial infection in any population. Valuable opportunities for tackling sexually transmitted diseases are present in primary care settings because most individuals of the target group nd their way to this type of health service. However, discussing issues and asking about sexual history with asymptomatic patients requires good communication skills;8 training GPs in those skills would be necessary to give an opportunistic screening programme the best chance of success. .................
Authors’ affiliations
Veronique Verhoeven, Researcher, Department of General Practice Dirk Avonts, Researcher, Department of General Practice Andre Meheus, Director, Department of Epidemiology and Social Medicine
Margaretha Ieven, Director, Department of Medical Microbiology Herman Goossens, Director, Department of Medical Microbiology Paul Van Royen, Director, Department of General Practice University of Antwerp, Belgium
REFERENCES 1 2 3 4 5 6 7
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Wilson JS, Honey E, Templeton A, et al. A systematic review of the prevalence of Chlamydia trachomatis among European women. Hum Reprod Update 2002;8:385–94. Chief Medical Ofcer’s Expert Advisory Group. Main Report of the CMO’s Expert Advisory Group on Chlamydia trachomatis. London: Department of Health, 1998. Verhoeven V, Avonts D, Meheus A, et al. Chlamydial infection: an accurate model for opportunistic screening in general practice. Sex Transm Infect (in press). Fenton KA, Korovessis C, Johnson AM, et al. Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection. Lancet 2001;358:1851–4. De Sa AB, Gomes JP, Viegas S, et al. Genital infection by Chlamydia trachomatis in Lisbon: prevalence and risk markers. Fam Pract 2002;19:362–4. Vuylsteke B, Vandenbruaene M, Vandenbalcke P, et al. Chlamydia trachomatis prevalence and sexual behaviour among female adolescents in Belgium. Sex Transm Infect 1999;75:152–5. van Valkengoed IG, Morre SA, van den Brule AJ, et al. Low diagnostic accuracy of selective screening criteria for asymptomatic Chlamydia trachomatis infections in the general population. Sex Transm Infect 2000;76:375–80. Verhoeven V, Bovijn K, Helder A, et al. Discussing STIs: doctors are from Mars, patients from Venus. Fam Pract 2003;20:11–15.
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