title: Comparison of two methods of screening for genital chlamydial infection in women attending in general practice: cross sectional survey.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Cross sectional survey.
  
  
  METHODS
  Four general practices in northeast London.
  
  
  METHODS
  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.
  
  
  METHODS
  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 < or = 25 and all women who had had two or more partners in the past year would have detected 87% (20/23) of infections.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Sexually Transmitted Diseases, University College London Medical School.
authors.forename: L
authors.initials: L
authors.lastname: Grun
authors.forename: J
authors.initials: J
authors.lastname: Tassano-Smith
authors.forename: C
authors.initials: C
authors.lastname: Carder
authors.forename: A M
authors.initials: AM
authors.lastname: Johnson
authors.forename: A
authors.initials: A
authors.lastname: Robinson
authors.forename: E
authors.initials: E
authors.lastname: Murray
authors.forename: J
authors.initials: J
authors.lastname: Stephenson
authors.forename: A
authors.initials: A
authors.lastname: Haines
authors.forename: A
authors.initials: A
authors.lastname: Copas
authors.forename: G
authors.initials: G
authors.lastname: Ridgway
mesh_terms: D000328:Adult; D000367:Age Factors; D002690:Chlamydia Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000652:urine; D002692:Chlamydia trachomatis; D003430:Cross-Sectional Studies; D005194:Family Practice; D005260:Female; D006801:Humans; D008025:Ligases / Q000652:urine; D008403:Mass Screening / Q000379:methods*; D015999:Multivariate Analysis; D015995:Prevalence; D012725:Sexual Behavior; D014626:Vaginal Smears / Q000379:methods*
chemical_list: D008025:Ligases