A total of 7940 HPV 16/18-positive women were included with a median age was 40 years (range, 25–84 years); 6211 (78.22%) and 1895 (23.87%) were positive for HPV 16 and 18, respectively. Among them, 34.1% (2710/7940) were infected with multiple genotypes, 82.28% (6533/7940) had cytology results and 26.65% (2116/7940) women were diagnosed with CIN 3 + (Additional file 1: Table S1). The prevalence of CIN 3 + in HPV 16-positive women (1899/6211, 30.57%) was significantly higher than that of HPV 18 (260/1895, 13.72%) (P < 0.001). The prevalence of CIN 3 + increased with age and differed significantly (Additional file 1: Fig. S1) (P < 0.001). The proportion of CIN 3 + in women with vaginal bleeding (316/588, 53.74%) was significantly higher than that in women without (1800/7352, 24.48%) (P < 0.001).

Approximately 33.02% (2051/6211) of HPV 16-positive women had multiple infections, and that of HPV 18-positive women was 43.64% (827/1895). HPV 52, 58, 53, 81, 51, and 18 were common genotypes coinfecting with HPV 16, accounting for 22.09%, 16.43%, 11.21%, 10.24%, 9.36%, and 8.09%, respectively. HPV 18 often coinfected with HPV 16, 52, 58,53, 58, and 56, accounting for 17.91%, 16,72%, 11.43%, 9.17%, 8.95%, and 8.09%, respectively. Compared to single HPV 16 infection (Fig. 1A), HPV 16 + 33 was significantly associated with an increased risk of CIN 3 + (odds ratio [OR] = 1.722, 95% confidence interval [CI] 1.102–2.691). In contrast, HPV 16 + 39 (OR = 0.467, 95% CI 0.241–0.905), HPV 16 + 59 (OR = 0.301, 95% CI 0.127–0.712), HPV 16 + 42 (OR = 0.426, 95% CI 0.228–0.799), HPV 16 + 81 (OR = 0.575, 95% CI 0.348–0.950), HPV 16 + 51 (OR = 0.428, 95% CI 0.248–0.739), HPV 16 + 53 (OR = 0.592, 95% CI 0.358–0.981), and HPV 16 + 66 (OR = 0.378, 95% CI 0.157–0.909) were significantly involved with a lower risk of CIN 3+. Compared to single HPV 18 infection (Fig. 1B), HPV 18 + 33 (OR = 4.112, 95% CI 1.443–11.720), HPV 18 + 35 (OR = 4.486, 95% CI 1.775–11.335), HPV 18 + 58 (OR = 2.110, 95% CI 1.098–4.054), and HPV 18 + 16 (OR = 3.028, 95% CI 1.851–4.952) were related to a higher risk of CIN 3+.

Log odds ratio for CIN 3 + in coinfection of HPV 16 (A) or HPV 18 (B) and other HPV genotypes. The analyses took single HPV 16 or HPV 18 infection as a reference, respectively. The vertical solid line represents the null log odds ratio of 0.HPV, human papillomavirus; CIN 3+, cervical intraepithelial neoplasia grade 3 or more severe diagnoses

According to the presence of other hrHPV and lrHPV, the included women were classified into 12 groups (Table 1). The diagnoses were significantly different in HPV 16-positive groups (P < 0.001), while there was no significant difference in HPV 18-positive groups (P = 0.266) and HPV 16 + 18-positive groups (P = 0.068). Notably, the prevalence of CIN 3 + in single HPV 16 (1408/4160, 33.85%), single HPV 18 (149/1068, 13.95%), and HPV 16 + HPV 18 (27/82, 32.93%) were the highest among HPV 16, HPV 18 and HPV 16 + 18 positive groups, respectively.

The cytology results of 6533 included women were available (Table 2). Most (2932, 44.88%) had NILM cytology, 1514 (23.17%) had ASC-US, 906 (13.87%) had LSIL, 334 (5.11%) had ASC-H, 151 (2.31%) had AGC and 770 (11.79%) had HSIL+. As expected, the prevalence of CIN 3 + generally increased with the severity of cytologic abnormalities in HPV 16-positive women: NILM (11.4%), ASC-US (23.2%), LSIL (28.8%), ASC-H (72.3%), AGC (66.0%) and HSIL + (89.9%). Results in HPV 18-positive women showed a similar trend, and it was noteworthy that HPV 18-positive women with AGC had a relatively high prevalence of CIN 3 + (72.0%).

To further investigate the association between the abovementioned factors and CIN 3 + risk, we conducted two logistic regression analyses which took single HPV 16 infection (Table 3) and single HPV 18 infection as reference (Additional file 1: Table S2), respectively. Older age women (OR = 1.017, 95% CI 1.011–1.024) and those with vaginal bleeding (OR = 2.674, 95% CI 2.113–3.384) were at higher risk of CIN 3 + independently. HPV 16/18-positive women with cytologic abnormalities also had a higher risk of CIN 3+. Of note, HSIL + (OR = 65.466, 95% CI 50.234–85.316), ASC-H (OR = 17.339, 95% CI 13.223–22.736), and AGC (OR = 14.963, 95% CI 9.562–24.413) were associated with a substantially greater risk of CIN 3 + than that of NILM. As demonstrated in the logistics regression analysis using single HPV 16 infection as reference (Table 3), HPV 16 + other hrHPVs (OR = 0.621, 95% CI 0.511–0.755), HPV 16 + lrHPVs (OR = 0.620, 95% CI 0.436–0.883), and HPV 16 + lrHPVs + other hrHPVs (OR = 0.248, 95% CI 0.157–0.391) were associated with decreased risk of CIN 3 + . Meanwhile, regardless of the HPV infection patterns of HPV 18 infected women, the CIN 3 + risk of HPV 18 infection was lower than that of HPV 16 infection: single HPV 18 (OR = 0.327, 95% CI 0.255–0.420), HPV 18 + other hrHPVs (OR = 0.229, 95% CI 0.153–0.342), HPV 18 + lrHPVs (OR = 0.315, 95% CI 0.149–0.665) and HPV 18 + lrHPVs + other hrHPVs (OR = 0.210, 95% CI 0.094–0.467). However, there was no significant difference in CIN 3 + risk between single HPV 16 infection and HPV 16 + HPV 18 (OR = 0.747, 95% CI 0.364–1.534), HPV 16 + HPV 18 + other hrHPVs (OR = 0.710, 95% CI 0.322–1.562), or HPV 16 + HPV 18 + lrHPVs + other hrHPVs (OR = 0.370, 95% CI 0.076–1.801). The results of logistic regression analyses using single HPV 18 and HPV 16 infection as references were identical except for HPV infection patterns. Compared to single HPV 18 infection, the CIN 3 + risk did not differ significantly in HPV 18 + other hrHPVs (OR = 0.699, 95% CI 0.443–1.102), HPV 18 + lrHPVs (OR = 0.962, 95% CI 0.442–2.096) and HPV 18 + lrHPVs + other hrHPVs (OR = 0.641, 95% CI 0.280–1.468) (Additional file 1: Table S2).