P1-S5.32 The differential associations of HPV prevalence with other sexually transmitted infections in hormonal and non-hormonal contraceptive users
Authors: Soong T R , Gravitt P E , Gupta S B , Liaw K , Tadesse A , Phongnarisorn C , Wootipoom V , Yuenyao P , Celentano D D 
Published: July 2011

BackgroundThis study evaluated the associations of recent sexually transmitted infections (STIs) with cervical HPV prevalence among hormonal and non-hormonal contraceptive users.MethodsData came from a prospective study conducted in 1046 women aged 20–38 years with normal cervical cytology in Thailand. We assessed whether baseline HPV prevalence was predicted by STIs which were newly detected and laboratory-confirmed within 2 years prior to enrolment. Prevalence ratios (PRs) with 95% CIs were estimated using generalised linear models.ResultsBaseline prevalence of any HPV and high-risk (HR)-HPV were 19.9% and 8.7% respectively. Having genital chlamydia (CT) or gonorrhoea (NG) in the past 2 years was associated with increased risk of any HPV as well as HR-HPV infection after controlling for current and past sexual behaviours, age, contraceptive use and other concurrent STIs [adjusted PRs (aPRs) for any HPV: CT: 1.7 (95% CI 1.1 to 2.7), NG: 1.8 (95% CI 1.1 to 3.1); aPRs for HR-HPV: CT: 2.9 (95% CI 1.3 to 6.5); NG: 3.4 (95% CI 1.7 to 6.7)]. Association between CT and prevalent HR-HPV was statistically significant only among non-hormonal contraceptive users [aPR: 2.7 (95% CI 1.2 to 6.3)] but not among those using hormonal contraceptives in the past 2 years [aPR: combined oral contraceptive (COC) users: 1.1 (95% CI 0.5 to 2.4); users of depot medroxyprogesterone acetate (DMPA): 1.1 (95% CI 0.4 to 3.3)] (Abstract P1-S5.32 table 1). Association of NG with prevalent HR-HPV was observed among those who used COC [aPR: 6.2 (95% CI 2.2 to 17.7)] or DMPA [aPR: 3.5 (95% CI 1.1 to 10.9)] during the past 2 years but not among non-hormonal contraceptive users [aPR: 1.9 (95% CI 0.3 to 10.3)] (Abstract P1-S5.32 table 1). No significant association was found between other STIs and baseline prevalence of HR-HPV in this cohort.Abstract P1-S5.32 Table 1Association between recent genital infections and prevalent detection of high-risk HPV (N=1046)Total study population aStudy population stratified by use of contraceptives in the past 2 years*Detection of any HR-HPVDetection of any HR-HPVNon-hormonal contraceptive users (n=339)COC users (n= 294)DMPA users (n= 413)N = 1046, N (col %)HR-HPV+ n=91 (8.7%), n (row %)PR (95% CI)aPR‡(95% CI)PR (95% CI)aPR§(95% CI)PR (95% CI)aPR§(95% CI)PR (95% CI)aPR§(95% CI)Detection of the following in the past 2 years†Genital chlamydia No925 (88.4)72 (7.8)11111111 Yes121 (11.6)19 (15.7)2.02 (1.26 to 3.22)2.93 (1.33 to 6.47)3.73 (1.69 to 8.26)2.74 (1.18 to 6.34)1.70 (0.84 to 3.47)1.14 (0.54 to 2.39)1.22 (0.44 to 3.35)1.08 (0.35 to 3.28)Genital gonorrhea No1020 (97.5)84 (8.2)11111111 Yes26 (2.5)7 (26.9)3.27 (1.68 to 6.36)3.40 (1.73 to 6.65)2.31 (0.37 to 14.46)1.87 (0.34 to 10.29)4.24 (1.79 to 10.03)6.22 (2.18 to 17.73)3.29 (1.13 to 9.60)3.51 (1.13 to 10.93)Bacterial vaginosis No875 (83.7)74 (8.5)11111111 Yes171 (16.4)17 (9.9)1.18 (0.71 to 1.94)1.05 (0.63 to 1.75)1.03 (0.40 to 2.66)0.75 (0.31 to 1.82)1.04 (0.46 to 2.36)0.90 (0.40 to 2.03)1.57 (0.66 to 3.68)1.46 (0.57 to 3.70)Positive for HSV-2 serology No626 (59.9)47 (7.5)11111111 Yes420 (40.2)44 (10.5)1.40 (0.94 to 2.07)1.26 (0.83 to 1.91)1.99 (0.90 to 4.38)1.75 (0.78 to 3.90)1.53 (0.84 to 2.80)1.67 (0.89 to 3.15)0.88 (0.41 to 1.88)0.73 (0.30 to 1.79)The following covariates werenotfound to be statistically significantly associated with the outcomes (P>0.05) anddid notsignificantly influence the effect size of the primary association of interest (<10%), and hence were not included in the final models: parity, smoking status, as well as other parameters assessed for sexual behavior, including age of sexual debut, having new partner in the past year, number of sex partners in the past year, frequency of sex in last 6 months.HR-HPV: High-risk HPV, defined as HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 (IARC 2007).*Subjects wereformerlyenrolled in a 2-year study addressing the effects of hormonal contraceptive use on HIV acquisition (HC-HIV). These subjects were required to adhere to the self-selected contraceptive method for at least 1 year of follow-up in that study (Morrisonet al. AIDS. 2010;24:1778–81). These subjects were reconsented at the end of that study for inclusion in the current study.†Genital infections were detected in pelvic exams and confirmed by laboratory assays.‡Estimates adjusted for age at baseline of the current study, number of lifetime partners, partners having sex with others in last 6 months, male partner using condom in last 6 months, other concurrent genital infections, types of contraceptive use in the past 2 years.§Estimates adjusted for age at enrollment of the current study, number of lifetime partners, partners having sex with others in last 6 months, male partner using condom in last 6 months, other concurrent genital infections.COC, combined oral contraceptives; DMPA, depot medroxyprogesterone acetate; HSV-2, Herpes simplex virus 2; PR, Prevalence ratio.ConclusionsThe differential impact of recent hormonal contraceptive use on the associations of CT and NG with HR-HPV prevalence suggests that the observed correlations may be attributed to biologic interactions between the pathologies of HPV and CT or NG, and not merely residual confounding by shared sexual risks.