Poster Session

P26. Over-diagnosis of chlamydia genital infection: our experience with point-of-care testing.


[OBIOL SAIZ] Centro de Salud Sexual y Reproductiva Fuente de San Luis. Hospital Universitario Dr Peset. València, [LOZANO] Departament de Medicina Preventiva i Salut Pública, Ciències de l'Alimentació, Toxicologia i Medicina legal, Universitat de València, [CASELLES] Hospital General Universitario de Castellón, [RAMADA] Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.CIBER de Epidemiología y Salud Pública (CIBERESP)

Background: Chlamydia genital infection is a global public health issue. The World Health Organization (WHO) has promoted the development of diagnostic methods to facilitate early treatment (point-of-care techniques). These methods are considered very useful in developing countries because accessibility and early diagnosis are more important factors in these countries than other variables such as sensitivity or specificity. In recent years, several articles have been published creating controversy about the usefulness of these methods in developed countries due to their low sensitivity and specificity. Objective: To evaluate the positive predictive value of the "Quick Vue” point-of-care technique and describe the clinical characteristics of patients diagnosed with Chlamydia genital infection. Methods: Quick Vue is a point-of-care technique, consisting of an immunochromatographic test based on lateral flow immunoassay techniques. Between January/2014 and June/ 2015 a total of 140 patients with a suspected Chlamydia infection were tested using Quick Vue technique. Due to the high number of positive cases obtained with Quick Vue, on Sept 2014 the molecular biology technique DxCT/ NG/MG Auto-assay, which is an in vitro nucleic acid amplification test (NAAT), was also tested (as gold standard) in a convenience sample of 90 patients with suspected Chlamydia genital infection. True positive cases (TP) and Positive Predictive Value (PPV) of the Quick Vue technique were assessed. True positive cases were those patients with a positive result in both techniques. PPV was calculates using the formula: [PPV=TP/(TP+FP)]. Data on age, contraceptive method, request motive, treatment, post-treatment control and need to repeat treatment were collected for all true positive cases. Results: The Positive Predictive Value of the "Quick Vue” technique in our sample of patients was 17,7%. Women diagnosed with Chlamydia genital infection (true positive case) were 31 years-old, using condoms as contraceptive method who consults for altered bleeding patterns and has been treated with azithromycin. Conclusions: Quick Vue Quick Vue refers to a predictive positive value of 88.1% however in our sample "Quick Vue" presented very low positive predictive values, resulting in an overdiagnosis of Chlamydia infection with an unnecessary use of antibiotics. Since September 2015, we have used only the NAATs Seegene STI-7 technique for the diagnosis of Chlamydia genital infection.