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Sexually Transmitted Infections
 
Sex Transm Infect. 2011 June; 87(4): 305.
Published online 2011 April 1. doi:  10.1136/sextrans-2011-050009
PMCID: PMC3252597
Letter

Spontaneous remission of sexually transmitted diseases must be considered in randomised controlled trials

Mary Jane Rotheram-Borus,corresponding author1 Zunyou Wu,2 Li Li,1 Roger Detels,1 Li-Jung Liang,1 and and the NIMH Collaborative HIV/STD Prevention Trial Group

Randomised controlled trials that test biomedical interventions to reduce sexually transmitted infections (STIs) have had very mixed results,1 2 as have behavioural trials.3 4 It is only in the past 10 years that the field has recognised that chlamydia resolves itself without treatment in 50% of the cases,4 although the estimates range from 13% to 60%.5–7 The length of time to clear chlamydia infection varies from 60 days in women to up to 15 months in men.5 The speed of resolution is also subject to individual-level factors (eg, infection clears sooner in older people), making it difficult to determine sample sizes for randomised controlled trials with STI outcomes.

In a recent five-country trial,1 the determination of sample size to identify the necessary number of participants to demonstrate a reduction in bacterial STI was based primarily on chlamydia (65.8% of the bacterial infections observed at recruitment; 10.3% prevalence) and trichomoniasis among women (17.2% of infections; 4.89% prevalence). When we examined all the bacterial STIs 1 year later, the rates of chlamydia were more than 60% lower and the rates of trichomoniasis were 40% lower. Potentially, half of the new chlamydia and trichomoniasis infections may have spontaneously resolved, as suggested by the above studies, but the actual incidence rates may have been 25% more than those observed at 12 months (assuming a consistent rate of infection over time).

The emerging data on spontaneous remission rates raises serious questions on how to design effective evaluations to demonstrate reductions in STIs. Randomised controlled trials must be designed to have shorter periods between assessments. It is also likely that there is a variance in the rates of clearance, although it is unclear in what direction and for whom the variations will apply. Thus, the design of future multisite trials must cautiously estimate STI infections, given the emerging data on spontaneous remissions or clearing of infections, and consider much shorter follow-up periods, even for long-term longitudinal trials.

Footnotes

Funding: NIMH provided funding for this multisite study.

Competing interests: None.

Patient consent: All human subjects signed the informed consent forms that were reviewed and approved by the Institutional Review Boards at UCLA and the China CDC.

Ethics approval: UCLA SG-IRB; RTI IRB; Chinese Centers for Disease Control IRB.

Provenance and peer review: Not commissioned; internally peer reviewed.

References

1. NIMH Collaborative HIV/STD Prevention Trial Group Results of the NIMH Collaborative HIV/STD prevention trial of a community popular opinion leader intervention. J Acquir Immune Defic Syndr 2010;54:204–14. [PMC free article] [PubMed]
2. The Explore Study Group. Effects of a behavioural intervention to reduce acquisition of HIV infection among men who have sex with men: the EXPLORE randomised controlled study. Lancet 2004;364:41–50. [PubMed]
3. Wawer MJ, Sewankambo NK, Serwadda D, et al. Control of sexually transmitted diseases for AIDS prevention in Uganda: a randomized community trial. Rakai Project Study Group. Lancet 1999;353:525–35. [PubMed]
4. Gisselquist D, Potterat JJ. Confound it: latent lessons from the Mwanza trial of STD treatment to reduce HIV transmission. Int J STD AIDS 2003;14:179–84. [PubMed]
5. Golden MR, Schillinger JA, Markowitz L, et al. Duration of untreated genital infections with Chlamydia trachomatis: a review of the literature. Sex Transm Dis 2000;27:329–37. [PubMed]
6. Brunham RC, Rey-Ladino J. Immunology of chlamydia infection: implication for a Chlamydia trachomatis vaccine. Nat Rev Immunol 2005;5:149–61. [PubMed]
7. Parks KS, Dixon PB, Richey CM, et al. Spontaneous clearance of Chlamydia trachomatis infection in untreated patients. Sex Transm Dis 1997;24:229–35. [PubMed]

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