Table 2

Multivariate and univariate analysis for risk (HR) of developing cervical intraepithelial neoplasia grade 2 (CIN2) according to baseline Chlamydia trachomatis and high-risk human papillomavirus (hrHPV) DNA status

	N	C trachomatis positive at day 1 (N=354)			C trachomatis negative at day 1 (N=8087)			Multivariate model		Univariate model
	N	n	No of women with a CIN2 lesion due to any HPV type	Rate^*	n	No of women with a CIN2 lesion due to any HPV type	Rate^*	HR^† (95% CI)	p-value^‡	HR^† (95% CI)	p-value^‡
CIN2 due to any HPV type
Total	8441	354	32	2.76	8087	330	1.18	1.78 (1.23 to 2.58)	0.002	2.28 (1.58 to 3.28)	<0.0001
Negative for HPV16 and 18	7382	268	16	1.76	7114	226	0.91	1.74 (1.05 to 2.90)	0.033	1.86 (1.12 to 3.09)	0.017
Positive for HPV16 and/or 18	965	81	15	6.47	884	101	3.67	1.82 (1.06 to 3.14)	0.030	1.74 (1.01 to 3.00)	0.045

	N	n	No of women with a CIN2 lesion due to hrHPV type^§	Rate^*	n	No of women with a CIN2 lesion due to hrHPV type^§	Rate^*	HR^† (95% CI)	p-value^‡	HR^† (95% CI)	p-value^‡
CIN2 due to hrHPV^§ type
Total	8441	354	29	2.49	8087	296	1.06	1.55 (1.05 to 2.30)	0.028	2.28 (1.56 to 3.34)	<0.0001
Negative for all 12 tested^§ hrHPV types	5689	143	4	0.8	5546	114	0.58	1.35 (0.50 to 3.67)	0.554	1.33 (0.49 to 3.59)	0.579
Positive for ≥1 of 12 tested^§ hrHPV types	2629	204	24	3.75	2425	179	2.26	1.59 (1.04 to 2.44)	0.033	1.63 (1.07 to 2.50)	0.024

N: Total number of women with non-missing Chlamydia status and respective PCR status and at least one follow-up visit.
n: Number of women with positive/negative Chlamydia status and positive/negative PCR status and at least one follow-up visit.
↵* Number of women with a lesion per 100 person-years at risk.
↵† HR associated with being positive versus negative to Chlamydia at baseline for each model. For the ‘univariate—total’ estimates, HR is calculated using the full data. For the ‘univariate—negative/positive’ estimates, HR is calculated using data from each stratified HPV baseline status group. For the ‘multivariate—total’ estimates, HR is calculated after adjusting for HPV baseline status (positive or negative), age at study entry, number of lifetime sexual partners and smoking status (current smoker, former smoker, never smoked). Interactions between baseline HPV status and Chlamydia status were tested and proved to be insignificant (p-values of interactions are 0.905 and 0.768 in the models of CIN2 due to any HPV type and CIN2 due to any hrHPV type, respectively). For the ‘multivariate—negative/positive’ estimates, HR is estimated within each HPV baseline status group after including the interaction term between baseline Chlamydia status and baseline HPV status and adjusting for age at study entry, number of lifetime sexual partners and smoking status.
↵‡ p Value shows how significantly the estimated HRs differ from 1.
↵§ Includes HPV16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59.