What is the optimal time to retest patients with a urogenital chlamydia infection?

ISRCTN	ISRCTN12159453
DOI	https://doi.org/10.1186/ISRCTN12159453
Protocol serial number	-
Sponsor	Public Health Service
Funder	Public Health Service (GGD) Amsterdam

Submission date: 01/05/2017
Registration date: 09/05/2017
Last edited: 14/11/2017

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Infections and Infestations

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Plain English summary of protocol

Background and study aims
Chlamydia is a common sexually transmitted infection. The current guidelines recommend testing again after a chlamydia infection, but the best timing is not known. The aim of this study is to find the best time to retest after chlamydia treatment.

Who can participate?
Heterosexual patients of the Amsterdam STI clinic with a chlamydia infection, aged 12 or older

What does the study involve?
After being diagnosed and treated, participants are randomly allocated to be offered a retest either 8, 16 or 26 weeks later. Participants can choose to do this at home and send a self-collected sample by mail, or at the clinic. The number and percentage of participants retested and chlamydia infection rates are assessed up to 35 weeks later.

What are the possible benefits and risks of participating?
The benefit for the participant is that chlamydia re-infections are diagnosed and treated. There are no risks involved in participation.

Where is the study run from?
Public Health Service (GGD) Amsterdam (Netherlands)

When is the study starting and how long is it expected to run for?
May 2012 to April 2017

Who is funding the study?
Public Health Service (GGD) Amsterdam (Netherlands)

Who is the main contact?
Prof. Henry de Vries

Contact information

Prof Henry de Vries
Scientific

Public Health Service
Department of Infectious Diseases
Nieuwe Achtergracht 100
Amsterdam
1018WT
Netherlands

ORCID ID	0000-0001-9784-547X

Study information

Primary study design	Interventional
Study design	Single-centre randomized controlled trial
Secondary study design	Randomised controlled trial
Study type	Participant information sheet
Scientific title	What is the optimal time to retest patients with a urogenital chlamydia infection? A randomized controlled trial
Study objectives	The trialists postulated that in heterosexual visitors of the STI clinic with a urogenital chlamydia infection, the proportion being retested would be lower with a later timing of retest, and that the proportion positive would be higher with a later timing of retest. If so, the trialists envisioned an optimum timing to offer a retest, which would provide the highest yield of diagnosed reinfections.
Ethics approval(s)	The study was reviewed by the ethics committee of the Academic Medical Center, University of Amsterdam, Netherlands. The board exempted the study from a full review and written patient consent as it was a modification of current practice and did not apply to the Dutch law ‘Medical Research Involving Human Subjects Act (WMO)’.
Health condition(s) or problem(s) studied	Urogenital Chlamydia trachomatis infection
Intervention	A single-centre randomized controlled trial among urogenital chlamydia nucleic acid amplification test positive heterosexual Amsterdam STI clinic clients. After treatment, patients were randomly assigned for retesting 8, 16 or 26 weeks later. Patients could choose to do this at home (and send a self-collected sample by mail), or at the clinic. Retest uptake and chlamydia positivity at follow-up were calculated.
Intervention type	Other
Primary outcome measure(s)	1. The number and percentage of participants retested up to 35 weeks after inclusion 2. The proportion of participants who were CT positive, measured by nucleic acid amplification test, up to 35 weeks after inclusion
Key secondary outcome measure(s)	1. The number, percentage and chlamydia positivity proportion of participants who: 1.1. Returned more than 1 week before the assigned date 1.2. Returned at assigned date (this was defined as a visit in the period >1 week before, until 6 weeks after the assigned date) 1.3. Returned >6 weeks after the assigned date but no later than 35 weeks (8 months) after inclusion 1.4. Those who did not return within 35 weeks of inclusion
Completion date	01/04/2017

Eligibility

Participant type(s)	Patient
Age group	Mixed
Sex	All
Target sample size at registration	2500
Key inclusion criteria	1. Heterosexual patients of the Amsterdam STI clinic testing positive for urogenital chlamydia 2. Aged 12 years or older
Key exclusion criteria	Does not meet inclusion criteria
Date of first enrolment	01/05/2012
Date of final enrolment	01/03/2013

Locations

Countries of recruitment

Netherlands

Study participating centre

Public Health Service (GGD) Amsterdam

STI outpatient clinic
Department of Infectious Diseases
Weesperplein 1
Amsterdam
1018 WT
Netherlands

Results and Publications

Individual participant data (IPD) Intention to share	Yes
IPD sharing plan summary	Available on request
IPD sharing plan	The datasets generated during and/or analysed during the current study are/will be available upon request from Prof. Henry de Vries.

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Results article	results	01/02/2018		Yes	No
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes

Editorial Notes

14/11/2017: Publication reference added.