Table 3. Multivariable logistic regression analyses of predictors of non-response at the three follow-up data collection moments for participants who visited the STI clinics in Kennemerland, Hollands Noorden, and Twente (non-Amsterdam).

	Baseline		3-week follow-up non-response			6-month follow-up non-response			1-year follow-up non-response
	N	%	N	%	aOR	N	%	aOR	N	%	aOR
					(95%CI)			(95%CI)			(95%CI)
Total	163		86	53		91	56		101	62
Health goals
Low/med (score < 4.00)	83	51	49	57	1	49	54	-	57	56	1
High (score ≥ 4.00)	80	49	37	43	0.58 (0.31–1.08)	42	46	-	44	44	0.40 (0.18–0.75)
Intentions
Low/med (score < 2.67)	84	52	44	51	-	45	50	-	46	46	1
High (score ≥ 2.67)	79	48	42	49	-	46	51	-	55	55	2.16 (1.08–4.44)
Impulsiveness
Low/med (score < 2.63)	78	48	39	45	-	35	39	1	45	45	-
High (score ≥ 2.63)	85	52	47	55	-	56	62	2.97 (1.52–5.99)	56	55	-
Knowledge*
Low/med (score < 6.00)	91	56	48	56	-	56	62	1	60	59	-
High (score ≥ 6.00)	72	44	38	44	-	35	39	0.58 (0.30–1.12)	41	41	-
Risk perception for CT (own risk)
Low/med (score < 27.50)	84	52	44	51	-	52	57	1	58	57	1
High (score ≥ 27.50)	79	48	42	49	-	39	43	0.45 (0.23–0.88)	43	43	0.47 (0.23–0.94)

* Knowledge regarding sexual health, prevention of chlamydia and consequences of chlamydia diagnosis

Footnote: Categories do not all add up to 100%, as missing values are not shown. Statistical associations are shown in in italic when the p-value is equal to or smaller than 0.1, and in bold when the p-value is equal to or smaller than 0.05. Only variables that were pre-selected in the univariable analyses are shown here.

Abbreviations: aOR = adjusted odds ratio, CI = Confidence Interval; Low/med = Low/medium, CT = Chlamydia; STI = Sexually Transmitted Infection.