Table 1

Study characteristics for randomised control trials

Study	Setting	Study population	Study characteristics
Study	Clinic/community Country	Gender Sexual orientation Selection criteria for recall Recall test HIV status Number (N)	Intervention	Control	Recall interval*
Type of intervention: send home sampling kit
Sparks et al22	Clinic USA	▸ M (66%) in clinic group, F (33%) ▸ M (72%) in mail/clinic group, F (18%) ▸ Heterosexual ▸ Chlamydia or gonorrhoea diagnosis ▸ Chlamydia/gonorrhoea test ▸ HIV status not specified ▸ Number=122	Choice of home sampling or clinic retest with telephone/mail reminder	Clinic retest only with telephone/mail reminder	10 weeks
Xu et al23	Clinic USA	▸ Female ▸ Sexual orientation not specified ▸ Chlamydia diagnosis ▸ Chlamydia test ▸ HIV-negative or unknown status ▸ Number=1215	Home sampling kit mailed or pick up from clinic+phone call reminder	Clinic appointment+phone call reminder	3 months
Gotz et al24	Clinic Netherlands	▸ M (30%), F (70%) ▸ Heterosexual ▸ Chlamydia diagnosis ▸ Chlamydia test ▸ HIV-negative ▸ Number=216	Email reminder+home sampling kit	Email reminder+clinic retest	4–5 months
Cook et al25	Clinic and community USA	▸ Female ▸ Sexual orientation not specified ▸ Chlamydia, gonorrhoea or trichomoniasis diagnosis ▸ Chlamydia/gonorrhoea test ▸ HIV status not specified ▸ Number=388	Home sampling kit mailed or pick up from clinic	Postcard reminder	6 months, 12 months, 18 months after recruitment
Type of intervention: Phone call/letter
Malotte et al26 USA	Clinic USA	▸ M (43.7%), F (56.3%) ▸ Sexual orientation not specified ▸ Chlamydia or gonorrhoea diagnosis ▸ STD screen ▸ HIV status not specified ▸ Number=499	Group 2: Appointment card+verbal advice+financial incentive Group 3: Motivational counselling at baseline+phone call reminder at 3 months or letter Group 5: Appointment card+verbal advice+phone call reminder at 3 months Group 6: Motivational counselling at baseline, no reminder	Standard care (verbal advice): Groups 1 and 4	3 months
Type of intervention: SMS
Downing et al10	Clinic Australia	▸ M (48.9%), F(51.1%) ▸ Sexual orientation not reported ▸ Chlamydia diagnosis ▸ Chlamydia test ▸ HIV-negative or unknown ▸ Number=94	Standard advice+SMS reminder±financial incentive	Standard care (verbal advice)	10–12 weeks

*Recall interval is the time between baseline visit and reminder being sent/received. It does not include the window period in which reattendance was counted. STD, sexually transmitted disease.