Table 1

Participation retesting in CSI

	Number retested	Number invited retest^*	%	Univariate		Multivariate (N=2899)
	Number retested	Number invited retest^*	%	OR (95% CI)	p Value	OR (95% CI)	pLr
Socio-demographic data
Gender^†
Male	734	1177	62.4%	0.79 (0.68 to 0.91)	0.001	0.85 (0.71 to 1.02)	0.083
Female	2043	3014	67.8%	1	<0.001
Total (100%)	2777	4191	66.3%
Age group^†, years
16–19	581	960	60.5%	0.67 (0.57 to 0.80)	<0.001	0.70 (0.56 to 0.87)	0.002
20–24	1271	1899	66.9%	0.89 (0.77 to 1.04)	0.132	0.98 (0.81 to 1.18)	0.822
25–29	925	1332	69.4%	1		1
Total	2777	4191	66.3%
Education level^† ^‡
Low	125	217	57.6%	0.71 (0.60 to 0.84)	<0.001	0.61 (0.45 to 0.82)	0.001
Mid	894	1364	65.5%	0.51 (0.38 to 0.68)	<0.001	0.83 (0.70 to 1.00)	0.033
High	960	1318	72.8%	1		1
Total (69%)	1979	2899	68.3%
Ethnicity^†
Dutch	1478	2158	68.5%	1	<0.001	1
Surinamese/Antillean	549	897	61.2%	0.73 (0.62 to 0.85)	<0.001	0.75 (0.62 to 0.92)	0.006
Turkish/Moroccan	141	219	64.4%	0.83 (0.62 to 1.11)	0.215	0.89 (0.61 to 1.29)	0.527
Sub-Saharan Africa	158	268	59.0%	0.66 (0.55 to 0.86)	0.002	0.62 (0.45 to 0.86)	0.004
Other	451	649	69.5%	1.05 (0.87 to 1.27)	0.613	1.08 (0.85 to 1.37)	0.531
Total	2777	4191	66.3%
Screening area
Rotterdam	1292	1940	66.6%	1.17 (0.90 to 1.51)	0.235
Amsterdam	1306	1967	66.4%	1.16 (0.90 to 1.50)	0.263
South Limburg	179	284	63.0%	1	0.487
Total	2777	4191	66.3%
SES^‡
High	81	123	65.9%	1	0.404
High average	328	520	63.1%	0.89 (0.59 to 1.34)	0.565
Low average	565	838	67.4%	1.07 (0.72 to 1.60)	0.729
Low	1690	2542	66.5%	1.03 (0.70 to 1.51)	0.885
Total (96%)	2664	4023	66.2%
Community risk
Low	652	1000	65.2%	1	0.717
Medium	1401	2105	66.6%	1.00 (0.85 to 1.16)	0.950
High	724	1086	66.7%	0.94 (0.78 to 1.12)	0.480
Total	2777	4191	66.3%
Screening round^†
1	1179	1737	67.9%	1.15 (0.98 to 1.35)	0.093
2	902	1380	65.4%	1.02 (0.87 to 1.21)	0.774
3	696	1074	64.8%	1	0.170
Total	2777	4191	66.3%
Behavioural data (self-reported data)^§
Index case treated for infection at T0
Yes	1120	1492	75.1%	1
No	120	190	63.2%	0.57 (0.41 to 0.78)	0.001
Total (40%)	1240	1682	73.7%
Current partner treated when indicated
No	161	222	72.5%	1.01 (0.72 to 1.40)	0.959
Yes	631	868	72.7%	1
Total (26%)	792	1090	72.7%
History of STI
No	396	542	73.1%	1
Yes	309	450	68.7%	1.24 (0.94 to 1.63)	0.129
Total (24%)	705	992	71.1%
Age at first sex
<16 years	730	1125	64.9%	1	0.001
16–18 years	1005	1447	69.5%	1.23 (1.04 to 1.45)	0.014
19 years and above	234	309	75.7%	1.69 (1.27 to 2.25)	<0.001
Total (69%)	1969	2881	68.3%
Number of lifetime partners
1	40	52	76.9%	1	0.104
2–5	154	244	63.1%	0.51 (0.26 to 1.03)	0.060
6 or more	287	417	68.8%	0.66 (0.34 to 1.30)	0.233
Total (17%)	481	713	67.5%

↵* Numerator available from population register data except education level that was assessed in an additional questionnaire.
↵† Variable included in model.
↵‡ SES level could not be calculated for all participants, educational level is derived from a voluntary questionnaire.
↵§ Due to small numbers for behavioural data, these variables were not included in multivariate analysis. If denominator is lower than 100%, the percentage is stated.
CSI, Chlamydia Screening Implementation Programme; SES, socio-economic status.