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Persistence of HPV in a cohort of female adolescents
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Persistence of HPV in a cohort of female adolescents

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    1. Persistence of HPV in a cohort of female adolescents Erika Samoff, Emilia H. Koumans, Lauri E. Markowitz, Maya Sternberg, Mary K. Sawyer, David Swan, John R. Papp, William Secor, Elizabeth R. Unger Centers for Disease Control (CDC), Emory University Dept. of Pediatrics

    2. Background HPV and Cervical Cancer HPV is necessary but not sufficient to cause cervical cancer Other sexually transmitted infections may affect HPV persistence and development of cancer C. trachomatis has been associated with cervical cancer Infection with human papilloma virus, here abbreviated HPV, is a necessary but not sufficient cause of most cervical cancers However, as most HPV infections are cleared by the host immune system, its likely that host or external cofactors are required for progression to cancer. It is possible that other sexually transmitted diseases act as cofactors in this way. And in fact, exposure to C. trachomatis has been associated with cervical cancer in serologic studies. While the mechanism by which c.t. or other sexually transmitted diseases may affect progression to cancer is not known, it is possible that infection with another organism during HPV infection may affect the host ability to clear the virus.Infection with human papilloma virus, here abbreviated HPV, is a necessary but not sufficient cause of most cervical cancers However, as most HPV infections are cleared by the host immune system, its likely that host or external cofactors are required for progression to cancer. It is possible that other sexually transmitted diseases act as cofactors in this way. And in fact, exposure to C. trachomatis has been associated with cervical cancer in serologic studies. While the mechanism by which c.t. or other sexually transmitted diseases may affect progression to cancer is not known, it is possible that infection with another organism during HPV infection may affect the host ability to clear the virus.

    3. Background HPV Persistence Persistence of HPV infection is associated with development of cervical cancer Concurrent infection (HPV and another genital tract infection) may alter host ability to clear virus Infection with >1 HPV type may affect the probability of persistence Persistence of HPV infection over time is strongly associated with the development of cervical cancer. If infection with an additional organism is associated with progression to cancer, this effect may happen at the level of persistence; that is, concurrent infection with HPV and another organism may affect the hosts ability to clear HPV , increasing persistence, and thereby facilitating progression to cancer. If infection with >1 HPV type creates an added burden for the host immune system, infection with >1 HPV type may similarly affect progression to cancer Persistence of HPV infection over time is strongly associated with the development of cervical cancer. If infection with an additional organism is associated with progression to cancer, this effect may happen at the level of persistence; that is, concurrent infection with HPV and another organism may affect the hosts ability to clear HPV , increasing persistence, and thereby facilitating progression to cancer. If infection with >1 HPV type creates an added burden for the host immune system, infection with >1 HPV type may similarly affect progression to cancer

    4. Study objective To assess whether concurrent infection with C. trachomatis, other organisms, or additional HPV types are associated with HPV persistence. Therefore, our study objective was to assess whether concurrent infection with C. trachomatis, other organisms, or additional HPV types are associated with HPV persistenceTherefore, our study objective was to assess whether concurrent infection with C. trachomatis, other organisms, or additional HPV types are associated with HPV persistence

    5. Methods Study Population Adolescent primary care clinic in public hospital, Atlanta GA Inclusion: Adolescent (age 12-19) Sexually active Exclusion HIV-infected Pregnant Female This prospective longitudinal cohort was recruited from adolescents attending primary care clinic located in a public hospital in downtown Atlanta, GA Inclusion criteria were adolescent age and sexual activity; clinic attendees were excluded if HIV-infected or pregnant. For this analysis, the study cohort was further limited to female study participantsThis prospective longitudinal cohort was recruited from adolescents attending primary care clinic located in a public hospital in downtown Atlanta, GA Inclusion criteria were adolescent age and sexual activity; clinic attendees were excluded if HIV-infected or pregnant. For this analysis, the study cohort was further limited to female study participants

    6. Methods Data collection and laboratory methods Study visits Behavioral and exposure data Urine, vaginal, and cervical samples 6 month intervals Laboratory analyses HPV: Roche line-blot assay (37 HPV types) C. trachomatis and N. gonorrheae: Nucleic acid amplification tests T. vaginalis: wet mount Bacterial vaginosis: Gram stain scored with Nugents criteria Behavioral and exposure data and urine, vaginal, and cervical samples were collected at 6 month intervals HPV was detectd and typed in cervical samples using the Roche line-blot assay Chlamydia and gonorrhea were detected in cervical or urine samples using nucleic acid amplification tests Trichomonas was detected in vaginal samples (?) by wet mount Bacterial vaginosis was detected using Nugents criteria to score gram stains of vaginal secretions (?)Behavioral and exposure data and urine, vaginal, and cervical samples were collected at 6 month intervals HPV was detectd and typed in cervical samples using the Roche line-blot assay Chlamydia and gonorrhea were detected in cervical or urine samples using nucleic acid amplification tests Trichomonas was detected in vaginal samples (?) by wet mount Bacterial vaginosis was detected using Nugents criteria to score gram stains of vaginal secretions (?)

    7. Methods HPV Persistence Analysis population Study participants with detection of HPV and a following visit separated by at least 6 months Persistent outcome detection of the same HPV type at a pair of sequential visits separated by at least 6 months Unit of analysis was pairs of visits (high risk and low risk) Coinfection was assessed at the initial of the pair of visits Our outcome of interest was HPV persistence. The population for this analysis consisted of study participants with HPV detection and at least one visit following detection, with at least a 6 month gap between viists. A Persistent outcome was defined as detection of the same HPV type at two subsequent visits separated by at least 6 months. Our unit of analysis was a pair of sequential visits . Therefore, >1 outcome could be contributed to the analysis by one study participant. In effect, we are evaluating associations with persistence of HPV infection from one visit to the next. Type-specific outcomes were grouped as high-risk or low-risk. Coinfection was assessed at the initial of the pair of visitsOur outcome of interest was HPV persistence. The population for this analysis consisted of study participants with HPV detection and at least one visit following detection, with at least a 6 month gap between viists. A Persistent outcome was defined as detection of the same HPV type at two subsequent visits separated by at least 6 months. Our unit of analysis was a pair of sequential visits . Therefore, >1 outcome could be contributed to the analysis by one study participant. In effect, we are evaluating associations with persistence of HPV infection from one visit to the next. Type-specific outcomes were grouped as high-risk or low-risk. Coinfection was assessed at the initial of the pair of visits

    8. Methods HPV persistence To make this clearer, lets look at a diagram: This diagram shows two study participants, with three study visits each. The population for analysis includes pairs of visits with an HPV diagnosis at the initial visit and a following visit separated by at least 6 months. So these pairs are in the analysis; this one is not. For woman 1, only the pair visit 2 and 3 are included in the analysis. She has HPV 6 infection at visit 2 and visit 3, separated by at least 6 months; this contributes a persistent outcome, and coinfection is assessed at visit 2. Woman 2 has HPV 18 infection at visit 1 and HPV 16 at visit 2; since 18 is not detected at the following visit this is not a persistent outcome. She has HPV 16 infection at visit 2 and visit 3; this is a persistent outcome. Coinfection is assessed at visit 1 and visit 2, the initial visits of the two visit pairs. After type-specific assessment of persistence, HPV detections were grouped into high-risk types (shown in pink) and low risk types (blue)To make this clearer, lets look at a diagram: This diagram shows two study participants, with three study visits each. The population for analysis includes pairs of visits with an HPV diagnosis at the initial visit and a following visit separated by at least 6 months. So these pairs are in the analysis; this one is not. For woman 1, only the pair visit 2 and 3 are included in the analysis. She has HPV 6 infection at visit 2 and visit 3, separated by at least 6 months; this contributes a persistent outcome, and coinfection is assessed at visit 2. Woman 2 has HPV 18 infection at visit 1 and HPV 16 at visit 2; since 18 is not detected at the following visit this is not a persistent outcome. She has HPV 16 infection at visit 2 and visit 3; this is a persistent outcome. Coinfection is assessed at visit 1 and visit 2, the initial visits of the two visit pairs. After type-specific assessment of persistence, HPV detections were grouped into high-risk types (shown in pink) and low risk types (blue)

    9. Methods Regression Analysis Associations with persistence measured using logistic regression Generalized estimating equations allows for analysis of correlated data exchangeable correlation structure robust standard errors Logistic regression was used to evaluate associations with persistent events We used generalized estimating equations to do our regression analysis; this technique allows logistic regression to be used with longitudinal data and addresses the inherent correlation between study visits. We used an exchangeable correlation structure, and conclusions were based on robust standard errors.Logistic regression was used to evaluate associations with persistent events We used generalized estimating equations to do our regression analysis; this technique allows logistic regression to be used with longitudinal data and addresses the inherent correlation between study visits. We used an exchangeable correlation structure, and conclusions were based on robust standard errors.

    10. Results Study Population N=282 (at least 2 study visits) For this analysis, we evaluated results from 282 women recruited into the study cohort with at least two study visits The median age was 16, and the median lifetime number of sex partners was 4, with a rather wide range. The median duration of follow-up was 9 months, also with a wide range; and most study participants had between 5 and 8 months between study visits.For this analysis, we evaluated results from 282 women recruited into the study cohort with at least two study visits The median age was 16, and the median lifetime number of sex partners was 4, with a rather wide range. The median duration of follow-up was 9 months, also with a wide range; and most study participants had between 5 and 8 months between study visits.

    11. Results Cumulative HPV detection Cumulative HPV prevalence was high in this group; over the course of the study, a low-risk HPV type was detected in 51% of study participants and a high-risk type was detected in 72% of study participants. Infection with >1 HPV type was also common; over the course of the study, multiple infection was detected in 48% of study participantsCumulative HPV prevalence was high in this group; over the course of the study, a low-risk HPV type was detected in 51% of study participants and a high-risk type was detected in 72% of study participants. Infection with >1 HPV type was also common; over the course of the study, multiple infection was detected in 48% of study participants

    12. Results Cumulative detection of other genital tract infections The prevalence of other genital tract infections was also quite high; chlamydia was detected in 43% of study participants over the course of the study, gonorrhea in 20%, trichomonas in 23%, and bacterial vaginosis in 49%.The prevalence of other genital tract infections was also quite high; chlamydia was detected in 43% of study participants over the course of the study, gonorrhea in 20%, trichomonas in 23%, and bacterial vaginosis in 49%.

    13. Results HPV persistence Presented here is the number of persistent events detected in this study. The numerator here is the number of pairs of visits with a persistent outcome; the denominator is the total number of pairs of visits with HPV detected at the first visit and at least 6 months before the second visit. Of those pairs of visits separated by at least 6 months,, 18% of low-risk infections were persistent, while 43% of high risk infections were persistent; as would be expected, more high risk infections than low-risk infections persisted.Presented here is the number of persistent events detected in this study. The numerator here is the number of pairs of visits with a persistent outcome; the denominator is the total number of pairs of visits with HPV detected at the first visit and at least 6 months before the second visit. Of those pairs of visits separated by at least 6 months,, 18% of low-risk infections were persistent, while 43% of high risk infections were persistent; as would be expected, more high risk infections than low-risk infections persisted.

    14. Results: Univariate Logistic Regression Associations with high-risk HPV persistence Univariate and multivariate logistic regression were used to evaluate our study objective; as no significant associations were detected with low-risk persistence, results for high-risk persistence only are presented here. On univariate analysis, infection with chlamydia and infection with >1 HPV type at the initial visit were associated with persistence to the second visit; infection with gonorrhea, trichomonas,and bacterial vaginosis were not. Univariate and multivariate logistic regression were used to evaluate our study objective; as no significant associations were detected with low-risk persistence, results for high-risk persistence only are presented here. On univariate analysis, infection with chlamydia and infection with >1 HPV type at the initial visit were associated with persistence to the second visit; infection with gonorrhea, trichomonas,and bacterial vaginosis were not.

    15. Results: Multivariate Logistic Regression Associations with high-risk HPV persistence Multivariate analysis was used to assess independent associations between additional infecting organisms and hpv persistence. Chlamydia infection and infection with >1 HPV types were independently associated with this outcome.Multivariate analysis was used to assess independent associations between additional infecting organisms and hpv persistence. Chlamydia infection and infection with >1 HPV types were independently associated with this outcome.

    16. Results Factors not associated with persistence of high-risk HPV types Frequency of sex act (vaginal, anal, or oral) in the previous 90 days Number of sex partners in the previous 90 days Number of lifetime sex partners before HPV detection Several other variables were evaluated in univariate and multivariate analysis for association with HPV persistence. As infection at the second visit may represent reinfection rather than persistence, we evaluated whether frequency of sex or sex partners between visits were associated with a persistent outcome. As the number of lifetime sexual partners is associated with HPV infection, this was also evaluated. None of these factors were associated with persistence. As douching and oral contraceptive use affect the vaginal epithelium, the role of these factors was assessed; neither were associated with persistence in this population. As smoking has been associated with the development of cancer in other studies, we assessed whether there is an association with persistence; an association was seen in univariate analysis which was not significant in multivariate analysis.Several other variables were evaluated in univariate and multivariate analysis for association with HPV persistence. As infection at the second visit may represent reinfection rather than persistence, we evaluated whether frequency of sex or sex partners between visits were associated with a persistent outcome. As the number of lifetime sexual partners is associated with HPV infection, this was also evaluated. None of these factors were associated with persistence. As douching and oral contraceptive use affect the vaginal epithelium, the role of these factors was assessed; neither were associated with persistence in this population. As smoking has been associated with the development of cancer in other studies, we assessed whether there is an association with persistence; an association was seen in univariate analysis which was not significant in multivariate analysis.

    17. Conclusions Co-infection with C. trachomatis is associated with persistence of high-risk HPV types Infection with >1 HPV type is associated with persistence of high-risk HPV types. Therefore, the conclusion from this analysis is that infection with chlamydia or multiple HPV types at the time of HPV detection are associated with HPV persistence for a period of at least 6 monhts. These results are in concordance with associations detected between chlamydia infection and cervical cancer in many other studies, and suggest a mechanism by which chlamydia may affect progression to cervical cancer. This study, unlike serological analyses, evaluates the effect of infection with chlamydia and HPV at the same time; these results are therefore a novel contribution to understanding the role of chlamydia infection in cervical cancer. Infection with multiple HPV types has been associated with persistence in some studies and not in others; given these conflicting results, the role of infection with >1 HPV type in persistence is not clear. Therefore, the conclusion from this analysis is that infection with chlamydia or multiple HPV types at the time of HPV detection are associated with HPV persistence for a period of at least 6 monhts. These results are in concordance with associations detected between chlamydia infection and cervical cancer in many other studies, and suggest a mechanism by which chlamydia may affect progression to cervical cancer. This study, unlike serological analyses, evaluates the effect of infection with chlamydia and HPV at the same time; these results are therefore a novel contribution to understanding the role of chlamydia infection in cervical cancer. Infection with multiple HPV types has been associated with persistence in some studies and not in others; given these conflicting results, the role of infection with >1 HPV type in persistence is not clear.

    18. Acknowledgements Study participants Study interviewers Study Coordinators Sakinah Carter Antonya Pierce Jamia Holland April Cameron CDC/DSTDP Emily Koumans Lauri Markowitz Eileen Dunne Deblina Datta Maya Sternberg Elizabeth R. Unger Id like to gratefully acknowledge the GRASP study participants and interviewers, study coordinators, Emily Koumans and my other colleagues at the division of sexually transmitted disease prevention at CDC, and Maya Sternberg and Elizabeth Unger for their hard work and contribution to this analysis Id like to gratefully acknowledge the GRASP study participants and interviewers, study coordinators, Emily Koumans and my other colleagues at the division of sexually transmitted disease prevention at CDC, and Maya Sternberg and Elizabeth Unger for their hard work and contribution to this analysis