Table 4

Summary table of reattendance/retest outcomes for observational studies

Study	Outcomes
	Reattendance (number reattending/number reminded to retest)
	Reattendance in intervention group n/N (%)	Reattendance in control group n/N (%)	Crude OR (95% CI), statistical finding*
Type of intervention: SMS
Bourne et al27	460/714 (64%)†	Concurrent control: 322/1084 (29.7%) Preintervention group: 543/1753 (31%)	Concurrent control: 4.5 (calc 95% CI 3.5 to 5.5) Historical control: 3.1 (calc 95% CI 2.5 to 3.8)
Zou et al28	885/997 (89%)	Concurrent control: 978/1382 (70.8%) Historic control: 1454/1800 (80.8%)	Concurrent control: calc OR=3.3 (calc 95% CI 2.6 to 4.1) Historic control: calc OR=1.9 (calc 95% CI 1.5 to 2.4)
Burton et al29	90/273 (33%)	92/266 (35%)	Calculated OR=0.93 (calc 95% CI 0.65 to 1.33)
Guy et al9	42/141 (30%)	Concurrent control: 50/202 (25%) Historic control: 71/338 (21%)	Concurrent control:1.26 (95% CI 0.78 to 2.06) Historical control: 1.57 (95% CI 1.01 to 2.46)
Type of intervention: Postcard/letter
Paneth-Pollak et al30	179/1267 (14.1%)	Non-intervention group: 288/3861 (7.5%) Preintervention: 94/1092 (8.6%)	Non-intervention: calc OR=2.0 (calc 95% CI 1.7 to 2.5) Preintervention: calc OR=1.7 (calc 95% CI 1.3 to 2.3)
Type of intervention: Phone
Harte et al31	206/301 (68%)	N/A	N/A
Type of intervention: send home sampling kit
Bloomfield et al32	70/399 (17.5%)‡	N/A	N/A
Gotz et al33	2777/4191 (66.3%)	N/A	N/A
LaMontagne et al34	417/592 (70.4%)	N/A	N/A
Walker et al35	3 months: 40/55 (73%) 6 months: 889/1116 (80%) 12 months: 887/1116 (79%)	N/A	N/A
Cameron et al36	215/330 (65%)	N/A	N/A

*OR and 95% CI is calculated where not provided in the paper and is specified as ‘calc OR’ or ‘calc 95% CI’.
†Data obtained from author.
‡399 is used as the denominator in the paper by Bloomfield et al as this is the number that was invited. Ghost addresses and refusals were then taken out. This allows for consistency with the other included studies.