Comparison of two methods of screening for genital chlamydial infection in women attending in general practice: cross sectional survey

• Published in: BMJ Vol. 315; no. 7102; pp. 226 - 230
• Main Authors: Grun, Lucia, Tassano-Smith, Julia, Carder, Caroline, Johnson, Anne M, Robinson, Angela, Murray, Elizabeth, Stephenson, Judith, Haines, Andrew, Copas, Andrew, Ridgway, Geoffrey
• Format: Journal Article
• Language: English
• Published: London British Medical Journal Publishing Group 26.07.1997; British Medical Association; BMJ Publishing Group LTD; BMJ Publishing Group
• Edition: International edition
• Subjects: Adult; Age Factors; Biological and medical sciences; Chlamydia Infections - diagnosis; Chlamydia Infections - epidemiology; Chlamydia Infections - urine; Chlamydia trachomatis; Cross-Sectional Studies; Family Practice; Female; General aspects; General practice; Human infectious diseases. Experimental studies and models; Humans; Immunoenzyme techniques; Infections; Infectious diseases; Ligase chain reaction; Ligases - urine; Mass Screening - methods; Medical sciences; Medical screening; Multivariate Analysis; Nurses; Prevalence; Screening tests; Sexual Behavior; Sexually transmitted diseases; Specimens; STD; Urine; Vaginal smears; Vaginal Smears - methods; Women; Human; Evaluation; Prevalence; Chlamydiaceae; Enzyme; General practitioner; Chlamydia trachomatis; Health education; Enzyme immunoassay; Biological activity; Genital diseases; Polymerase chain reaction; Sexually transmitted disease; Ligases; Cross sectional study; Chlamydiales; Bacteria; Female; Public health; Comparative study
• ISSN: 0959-8138; 0959-8146; 1468-5833; 1756-1833
• DOI: 10.1136/bmj.315.7102.226

Abstract Objectives: To estimate the prevalence of Chlamydia trachomatis in asymptomatic women attending general practice; to assess the potential of the ligase chain reaction as a screening tool; and to evaluate selective screening criteria. Design: Cross sectional survey. Setting: Four general practices in northeast London. Subjects: 890 women aged 18-35 years attending general practice for a cervical smear or a “young well woman” check between October 1994 and January 1996. The women were tested for C trachomatis with confirmed enzyme immunoassay (endocervical specimens) and ligase chain reaction assay on urine specimens. Main outcome measures: Prevalence of C trachomatis infection in women aged 18-35 on the basis of each test; sensitivity and specificity of both tests in this population. Results: Prevalence of confirmed infection was 2.6% (95% confidence interval 1.6% to 3.6%) in all women. Prevalence on the basis of enzyme immunoassay was 1.6% (0.8% to 2.7%), with a sensitivity of 60% and a specificity of 100%. Prevalence on the basis of ligase chain reaction was 2.5% (1.5% to 3.9%), with 90% sensitivity and 99.8% specificity. Screening all women aged ≤25 and all women who had had two or more partners in the past year would have detected 87% (20/23) of infections. Conclusion: Ligase chain reaction on urine samples performs at least as well as enzyme immunoassay on cervical specimens in this low prevalence population. It offers potential as a non-invasive screening tool. A simple selective screening strategy might be appropriate and would be able to detect most cases of infection. However, a rigorous economic evaluation of possible screening strategies is needed first. Key messages Chlamydia trachomatis causes a common sexually transmitted infection, which is often asymptomatic but may lead to pelvic inflammatory disease, ectopic pregnancy, and tubal infertility in 10%-25% of infected women Over 1 in 20 women aged 18-25 years attending general practice may have undiagnosed infection New screening tests that do not require a cervical sample should improve the prospects for community based screening for chlamydia Rigorous evaluation of the cost effectiveness of such screening is now a priority