Ostergaard 2003.

Methods	Setting: 4 counties in Denmark Enrolment: participants enrolled between February 1999 to March 2000 Follow up: no follow‐up of index patient reported
Participants	562 index patients ( 414 women and 148 men) with a positive chlamydia swab were randomised Inclusion criteria Positive chlamydia swab Completed questionnaire Exclusion criteria No criteria specified
Interventions	Specimen collection package was posted to the index patient's home address. There were 5 specimen collection kits in this package. The index patient was instructed to give collection kits to his/her sexual partners of the previous 12 months. The collection kits were identical. For male partners the kit contained 10 mL tube to collect first void urine sample. The female partners received a vaginal pipette containing 5 mL sterile normal saline to be inserted into the vagina, flushed and aspirated Patient referral with home sampling (n = 304) Samples collected by the partners at home had to be posted directly to the diagnostic laboratory in postage paid and pre‐addressed envelopes Patient referral with office sampling (n = 258) Partners had to bring specimen collection kit into the office of a healthcare provider to obtain sample. Partners also brought a letter with them, explaining the study and the importance that the healthcare provider used the provided specimen collection kit to collect sample. The healthcare provider posted the sample to the laboratory
Outcomes	Primary outcome Proportion of index patients with at least 1 partner tested for Chlamydia trachomatis (laboratory results) Secondary outcomes Proportion of index patients with at least 1 partner positive for C. trachomatis (laboratory results)
Notes	Ethical approval by Danish ethics committee system Implied consent
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The index patient was randomised based on a positive swab sample ‐ no details given
Allocation concealment (selection bias)	Unclear risk	No details on allocation concealment given
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data for all partners of index patients available
Selective reporting (reporting bias)	Low risk	Outcomes in method same as in results. Protocol not available from 3 trial registries
Other bias	Low risk	No other bias identified
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Specimen collection kits for the 2 study groups were identical and the index patient was blinded to content of the specimen collection kit. However there is no guarantee that the index patient did not open the package before forwarding to partner The healthcare provider, who did the office sampling, was not part of the study. They only collected the samples and posted it to the study centre
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It is not mentioned whether laboratory personnel were blinded. However, the chlamydia test is an objective outcome measure