Diagnosis of urogenital Chlamydia trachomatis infection in women based on mailed samples obtained at home: multipractice comparative study

Abstract

Objective: To compare urine and vaginal flush samples collected by women at home with endocervical and urethral swabs obtained by general practitioners for their efficacy in the diagnosis of urogenital Chlamydia trachomatis infection. Design: Multipractice comparative study. Setting: 33 general practices and a central department of clinical microbiology in Aarhus County, Denmark. Subjects: 222 women aged 18–25 years who for any reason had a gynaecological examination. Interventions: Endocervical and urethral swabs were obtained by the women's general practitioners. The same women when at home then collected a first void urine sample, a midstream urine sample, and a vaginal flush sample (using a vaginal pipette) and mailed them to the laboratory. Main outcome measures: C trachomatis detected by the polymerase chain reaction and the ligase chain reaction. Eight tests for C trachomatis were performed for every woman. When two of the eight yielded positive results the patient was considered infected. Results: The overall prevalence of C trachomatis infection was 11.2% (23/205 women). Test sensitivities in samples obtained by general practitioners, samples obtained at home subjected to polymerase chain reaction, and samples obtained at home subjected to ligase chain reaction were 91%, 96%, and 100% respectively. The corresponding specificities were 100%, 92.9%, and 99.5%. Conclusions: The diagnostic efficacy of samples obtained by women at home and mailed to the laboratory was as good as for samples obtained by a general practitioner when using the ligase chain reaction. This may have important implications for the practicability of screening for this common, often asymptomatic, and treatable infection. A combination of mailed samples obtained at home is necessary in order to obtain optimal diagnostic sensitivity; a single urine sample is not enough Mailed samples obtained at home may also be appropriate for diagnosis in young asymptomatic women with regular partners; these women have a high prevalence of urogenital C trachomatis infection The use of mailed self obtained samples in women might limit costs and increase the practicability of screening programmes for urogenital C trachomatis infection