Comparison of two methods of screening for genital chlamydial infection in women attending in general practice: cross sectional survey.
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.
Grun
L
L
Department of Sexually Transmitted Diseases, University College London Medical School.
Tassano-Smith
J
J
Carder
C
C
Johnson
A M
AM
Robinson
A
A
Murray
E
E
Stephenson
J
J
Haines
A
A
Copas
A
A
Ridgway
G
G
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*
D008025:Ligases