Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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Cost-effectiveness considerations for this test
- Wiley D. Jenkins (4 December 2007)
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Chlamydia Rapid Test Vs Syndromic Manangement-Cost effectiveness in Resource Poor Setting.
- Olufunso S Ojo (5 December 2007)
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Chlamydia Rapid Test and False Negatives
- Souhail Alouini (9 December 2007)
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Sensitivity vs negative predictive value
- yogi sehgal (24 February 2008)
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Wiley D. Jenkins, Assistant Professor Southern Illinois University School of Medicine, 913 N. Rutledge St, PO Box 19671, Springfield, IL 4
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I found the article quite interesting, but wonder at the test's potential for widespread adoption. Its ease of use and lack of expensive equipment make it very attractive. For this methodology to truly be cost- effective, considerations must be given to target populations and current treatment rates and time delays. For example, in the state of Illinois the overall treatment rate for women testing positive exceeds 90% for the past few years (unpublished data). However, only ~80% of those are treated within 30 days (leading to the referenced problem with the development of PID in the interim). I wonder that the widespread, general adoption of this test as a complement to the current methodologies would cost more than is saved by averted morbidity? However, its use in selected situations, such as for women who present to ER/ED for PID and are tested for chlamydia, might be quite useful. Finding these individuals later for standard test results is much more difficult than for those who present to a family planning clinic or private physician. I do not know the cost of the test in the UK, nor the local treatment rates, but I suspect that widespread adoption of this test, done in conjunction with standardized PCR, would not be cost- effective. I would be quite interested in seeing further work done to determine the best settings where this may be effectively applied. Competing interests: None declared |
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Olufunso S Ojo, Medical Doctor Currently applying, UK
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It is indeed a fascinating finding to my mind to finally reach the point of rapid testing for Chlamydia. Chlamydia up to this moment remains the world's most prevalent sexually transmitted bacterial infection. The diagnosis of this infection is increasing steadily in the developed world where tools are not only readily available for testing but also the awareness is there on the need to get tested. I say this in comparison to the developing world, where doubtfully most of the infections may be present but yet undiagnosed specifically as a result of unavailability of essential tools for this purpose. The World Health Organization’s recommendation for the low and middle -income countries which is the syndromic diagnosis and management has been the practice up till now. The advent of this novel approach to testing seems to be very well appropriate to match the possible prevalence in the developing world setting and the possible number of women that may require testing. Of course, it would be more apposite than the previously preferred method of testing which is the molecular test also known as nucleic acid amplification tests (NAAT) which is based on amplification of the DNA that is present in Chlamydia trachomatis. This is because the latter would require training of staff, having readily available reagents and equipment for this test, more hospital visits for patients, and loss of patients to follow up because of weeks of waiting to get the result. (Looking from a developing country viewpoint). Comparing rapid test with the syndromic diagnosis and treatment, one may be tempted to say, time has come to finally stop treating everyone ‘blindly’. That the true prevalence of Chlamydia can now be fully documented, for further action to be taken in developing world by rapid test, which is fast, less invasive or more private (very well appreciated in some developing countries). However, the question of the cost effectiveness of having specific diagnosis obtained before treatment compared to the arguably effective syndromic approach would need further research in resource poor settings. How sensitive and reproducible would the test be following treatment of first suspicion? Further questions that could be raised would be how the men would get tested? Would this replace the urine test in men? Competing interests: None declared |
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Souhail Alouini, Gynaecologist-obstetrician, M.D, Ph.D. R. Descartes University, Paris 75006
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Sensitivity and specificity of the Chlamydia Rapid Test using vaginal swab specimens in comparison to polymerase reaction assay or strand displacement amplification assay are high (> 80%) (1). The results are available within 30 minutes versus one to two weeks for nucleic acid amplification tests. Nevertheless, currently the Chlamydia Rapid Test cannot totally replace the PCR. Indeed, a recent study compared the sensitivity and specificity of the Chlamydia Rapid Test with the PCR (2). The study involved 1484 female sex workers attending a social hygiene clinic and 838 women attending an obstetrics-gynaecology clinic. In the high-risk population (female sex workers), 29% of women (1/4) infected by the chlamydia trachomatis had a negative Chlamydia Rapid Test (sensitivity 71%) compared with PCR. In low risk-population 13% of women (1/7) infected by the chlamydia had a negative Chlamydia Rapid Test (sensitivity 87%). In case of the discordance between the clinical symptoms and Chlamydia Rapid Test or in a high-risk population, the Chlamydia Rapid Test is insufficient and the PCR remains the gold standard. Finally, the medical cost of a widespread screening by Clamydia Rapid Test should be evaluated in relation to its medical benefit. References 1. Mahilum-Tapay L, Laitila V, Wawrzyniak JJ, Alexander S, Swain A, Barber P,Ushiro-Lumb I, Goh BT, Ison C, Lee HH. New point of care Chlamydia Rapid Test bridging the gap between diagnosis and treatment: performance evaluation study. BMJ 2007;335:1190-1194 2. Saison F, Mahilum-Tapay L, Michel CE, Buttress ND, Nadala EC Jr, Magbanua JP, Harding-Esch EM, Villaruel MO, Canong L, Celis RL, Lee HH. Prevalence of Chlamydia trachomatis Infection among Low- and High-Risk Filipino Women and Performance of Chlamydia Rapid Tests in Resource- Limited Settings. J Clin Microbiol. 2007;45:4011-7. Competing interests: None declared |
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yogi sehgal, family physician Sioux Lookout, p8t 1a8
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It's odd that this paper is being spun as positive. I'm not sure how reassured a woman would be to know that there is a 17% or almost 1 in 5 chance that the test misses the presence of chlamydia in the average population and and almost 1 in 3 chance in a high risk population. The only advantage of this test is its result's availability in 30 minutes, and I suspect the people that were willing to wait 30 min to 2 hours for the result were not the people that were not getting treated in the first place (the population that would be ideally served by this test). A simple approach given this evidence would be to treat empirically in a high risk person (i.e. obvious PID, symptomatic contact, etc.), do either a urine or a cervical culture/pcr specimen depending on the clinical scenario in the average woman, and save the rapid test for people that you will possibly not be able to follow up for the result (even if you give them a prescription to take if it's positive, so they don't have to come back in--i.e. living on the street or no phone number or mental health/addictions issues that might interfere, etc.). Competing interests: None declared |
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