Oakeshott 2010.

Methods	Study design: Individually randomised controlled trial comparing immediate with deferred screening Setting: common rooms, lecture theatres, and student bars at universities and further education colleges in London.. Study period: 1 year from acceptance of offer of chlamdia testing
Participants	Sexually active female students 16‐27 years (N = 2563) Inclusion criteria: Aged 27 or less Sexually active females Exclusion criteria: Never had sexual intercourse Had been tested for chlamydial infection in the past 3 months Pregnant
Interventions	Enrolment: Investigators personally recruited women in bars, common rooms and lecture theatres at 20 London universities and further education colleges, randomising them between September 2004 and October 2006. Intervention group: screening:1273 women randomised (but 14 excluded = 1259 included) Vaginal swab samples were obtained (at nearest lavatory) and analysed for C. trachomatis. In case of infection the woman was contacted and urged to contact a physician for treatment and partner notification. Control group:deferred screening:1290 randomised (but 20 excluded = 1270 included) Samples were obtained (at nearest lavatory) but stored for 12 months. Women were obliged to seek a health care provider if they considered themselves at risk or if they had symptoms (= standard care).
Outcomes	Primary outcomes Incidence of pelvic inflammatory disease in women evaluated in the 12 months after recruitment; assessed by a doctor as probable, with a clinical diagnosis of PID which was treated (modified Hager's criteria – pelvic pain, cervical motion tenderness, uterine or adnexal tenderness) Incidence of pelvic inflammatory disease in women evaluated in the 12 months after recruitment; assessed by a doctor as possible, with clinical features of PID (abdominal pelvic pain with features of PID, which may have responded to antimicrobial therapy, but no record of cervical excitation or uterine or adnexal tenderness; or longstanding abdominal pain consistent with endometriosis, but some features of PID – for example, uterine tenderness, and unable to confirm if antimicrobial therapy had a benefit) Secondary outcomes: none reported Outcomes measured via questionnaires, answered by participants by e‐mail, postal questionnaires or telephone calls. Non‐responders were followed up by contacting a GP.
Notes	The study was approved by Wandsworth research ethics committee (reference 03.0012). Trial registration number: NCT00115388. This study was supported by the BUPA Foundation (grant No 684/GB14B). TMA sample collecting kits were provided by Gen‐Probe (San Diego, CA).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Comment: random number tables were used (p. 2).
Allocation concealment (selection bias)	Low risk	Comment: Sealed sample packs, which contained the completed, unopened questionnaires and consent forms were allocated (blinded procedure) (p. 2).
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Comment: Participants were blind to group allocation except for those in the interventions group with baseline samples that tested positive for chlamydia and who were referred for treatment and 38 women with indeterminate test results who were asked to post a repeat sample (masking p. 2). Samples were obtained before allocation and therefore the recruiting personnel could not be aware of allocation. Not clear what happened with indeterminate results in control group if tested after 12 months.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: A panel of 3 genitourinary medicine physicians assessed patient questionnaires and medical records using standardised criteria; they were blinded to trial group (p. 2).
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: In the intervention group, 68 were lost to follow‐up; in the control group 84 were lost to follow‐up. These numbers are very low and unlikely to influence the results.
Selective reporting (reporting bias)	Low risk	Comment: The single primary aim from the protocol is reported in the publication. 2 primary aims from the introduction section are reported in the results. The protocol is available.
Other bias	High risk	Contamination of intervention: possibility of independent testing in the year of the study, which would reduce differences between the intervention and control group (about 22% in each group were tested); Received funding of diagnostic tests from manufacturer.