Quadrivalent HPV vaccine effectiveness against cervical intraepithelial lesion grade 2 or worse in Norway: A registry-based study of 0,9 million Norwegian women.

In Norway, single cohort vaccination with quadrivalent HPV (qHPV) vaccine targeting 12-year-old girls took place from 2009-2016. In 2020, the oldest vaccinated cohort was 23 years old and had approached the age where risk of being diagnosed with cervical intraepithelial lesion grade 2 or worse (CIN2+) increases rapidly. The aim of this cohort study was to assess direct qHPV vaccine effectiveness (VE) against CIN2+ among Norwegian women aged 16-30 in 2007-2020. By using population-based health registries and individual-level data on vaccination status and potential subsequent CIN2+ incidence, we found 82% qHPV VE among women vaccinated before the age of 17.

Sociodemographic characteristics associated with cervical cancer screening participation by send-to-all and opt-in HPV self-sampling: Who benefits? Results from a randomized controlled trial among long-term non-attending women in Norway.

With the objective to investigate associations between sociodemographic characteristics and participation in interventions designed to increase participation in cervical cancer screening among under-screened women, we randomized a random sample of 6000 women in Norway aged 35-69 years who had not attended cervical screening for ≥10 years to receive either (i) a reminder to attend regular screening (control), (ii) an offer to order a self-sampling kit (opt-in), or (iii) a self-sampling kit unsolicited (send-to-all). We analyzed how sociodemographic characteristics were associated with screening participation within and between screening arms. In the send-to-all arm, increased screening participation ranged from 17.1% (95% confidence interval [95% CI] = 10.3% to 23.8%) to 30.0% (95% CI = 21.5% to 38.6%) between sociodemographic groups. In the opt-in arm, we observed smaller, and at times, non-significant increases within the range 0.7% (95% CI = -5.8% to 7.3%) to 19.1% (95% CI = 11.6% to 26.7%). In send-to-all versus control comparisons, there was greater increase in participation for women in the workforce versus not (6.1%, 95% CI = 1.6% to 10.6%), with higher versus lower income (7.6%, 95% CI = 2.2% to 13.1%), and with university versus primary education (8.5%, 95% CI = 2.4% to 14.6%). In opt-in versus control comparisons, there was greater increase in participation for women in the workforce versus not (4.6%, 95% CI = 0.7% to 8.5%), with higher versus lower income (6.3%, 95% CI = 1.5% to 11.1%), but lower increase for Eastern European versus Norwegian background (-12.7%, 95% CI = -19.7% to -5.7%). Self-sampling increased cervical screening participation across all sociodemographic levels, but inequalities in participation should be considered when introducing self-sampling, especially with the goal to reach long-term non-attending women.

Understanding the high-risk human papillomavirus prevalence and associated factors in the European country with a high incidence of cervical cancer.

BACKGROUND: High-risk human papillomavirus (HR-HPV) is a known cause of cervical cancer (CC). Latvia has a high incidence of CC compared with the average incidence in the European Union. This study aims to fill the data gap on the HR-HPV burden in Latvia, providing information on its prevalence and associated factors. METHODS: The cross-sectional study was conducted from February 2021 to April 2022. Participants 25-70 years old visiting a general practitioner (general population) or those referred to a colposcopy clinic with changes in their cervical cytology (colposcopy population) collected vaginal self-sample and completed a paper-based questionnaire. Samples were analyzed with Cobas 6800 System (Roche) for HPV16, HPV18 and other HR-HPV (HPV31/33/35/39/45/51/52/56/58/59/66/68). Descriptive statistics for categorical variables were performed. The Chi-square test was used to determine for the statistical significance of differences in the proportions of the dependent variable between subgroups of the independent variable. Univariate and multivariate binary logistic regression were used to identify factors associated with positive HR-HPV status. Results were considered statistically significant at P < 0.05. RESULTS: A total of 1274 participants provided a valid sample. The prevalence of any HR-HPV infection was 66.8% in the colposcopy group and 11.0% in the general population. Factors associated with positive HR-HPV status were marital status single/divorced/widowed (vs. married/cohabiting) [adjusted OR (aOR) 2.6; P = 0.003], higher number of lifetime sex partners [aOR 5.1 (P < 0.001) and 4.0 (P = 0.001)] for six or more and three to five partners in the general population; in the colposcopy group, the statistical significance remained only for Latvian ethnicity (vs. other) (aOR 1.8; P = 0.008) and current smoking (vs. never) (aOR 1.9; P = 0.01). CONCLUSION: We documented a comparison to European Union HR-HPV infection burden in Latvia. Any HR-HPV positivity was significantly associated with sexual and other health behavior.

Real-world effectiveness of HPV vaccination against cervical neoplasia among birth cohorts ineligible for routine vaccination.

Human papillomavirus (HPV) vaccine effectiveness may differ between settings. Here we present the first real-world effectiveness study of HPV vaccination on high-grade cervical lesions from Norway, among women who received HPV vaccine outside the routine program. We performed an observational study of all Norwegian women born 1975 to 1996 and retrieved individual data from nationwide registries on HPV vaccination status and incidence of histologically verified high-grade cervical neoplasia during 2006 to 2016. We estimated the incidence rate ratio (IRR) and 95% confidence intervals (CI) for vaccination vs no vaccination by Poisson regression stratified by age at vaccination <20 years and ≥20 years. The cohort consisted of 832 732 women, of which 46 381 (5.6%) received at least one dose of HPV vaccine by the end of 2016. The incidence rate of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) increased with age regardless of vaccination status and was highest at age 25 to 29, at 637/100 000 among unvaccinated women, 487/100 000 among women vaccinated before age 20 and 831/100 000 among women vaccinated at age 20 or older. The adjusted IRR of CIN2+ between vaccinated and unvaccinated women was 0.62 (95% CI: 0.46-0.84) for women vaccinated below age 20, and 1.22 (95% CI: 1.03-1.43) for women vaccinated at age 20 or older. These findings indicate that HPV vaccination among women too old to be eligible for routine HPV vaccination is effective among women who are vaccinated below age 20 but may not have the desired impact among women who are vaccinated at age 20 or older.

A population-based cohort study on changes in breast, lung and colorectal cancer incidence and mortality among non-Western immigrant women.

BACKGROUND: Cancer risk varies geographically, and migrants are influenced by different risk factors before, during and after migration. Increased migration from non-Western countries to the Nordic countries calls for a better understanding of the migrants' cancer risk and the change in risk patterns over time. The aim of this study was to compare the incidence and mortality of breast, colorectal and lung cancer between non-Western immigrant and the native female population in Denmark, Finland, Iceland, and Norway. MATERIAL AND METHODS: Data from national registries were processed and pre-analysed in each country. Multivariate Poisson regression models were used to model the relative differences in incidence and mortality as rate ratios (RR). The country-specific estimates and summary statistics were pooled together using a random effects model. RESULTS: Non-Western immigrant women had significantly lower breast (RR 0.71, 0.65-0.78), colorectal (RR 0.72, 0.57-0.92) and lung (RR 0.55, 0.42-0.72) cancer incidence rates than native women, and the risk of these cancers among immigrant women increased with duration of residence. Differences were parallel in breast, colorectal and lung cancer mortality (RR 0.64, 0.55-0.74; RR 0.66, 0.48-0.92; RR 0.51, 0.34-0.79). Among immigrant women, higher education increased the risk for breast cancer and decreased it for lung cancer. CONCLUSION: The results significantly complement and add to the previous findings of cancer burden and cancer burden transition among migrants and provide evidence of a prolonged cancer risk advantage among non-Western immigrant women. However, the findings show an increasing risk of lifestyle-related cancers with increasing duration of residence in the host country. Further studies are needed to discover underlying reasons for this phenomenon.

Cervical, liver and stomach cancer incidence and mortality in non-Western immigrant women: a retrospective cohort study from four Nordic countries.

BACKGROUND: Cervical, liver and stomach cancers are the most common infection-associated malignancies and the leading cause of morbidity in non-Western regions. We compared the incidence and mortality of these cancers between non-Western immigrant and non-immigrant Nordic female populations. We also analysed the effect of age at immigration, duration of residence and education on cancer burden. MATERIAL AND METHODS: Study population consisted of women residents in Denmark, Finland, Iceland and Norway in 1973-2020. Non-Western women contributed 3.1% of the total 260 million person-years at risk. All women were followed from their 20th birthday, or from the date of immigration if after, until the date of their first primary cancer diagnosis, death, emigration, or the end of the country-specific study period. All data were adjusted for 10-year age groups and calendar periods, and immigrant data was further broken down by region of birth, age at immigration and education level. Country-specific estimates were produced by multivariable Poisson regression and pooled in Finland with a random effects model. RESULTS: Altogether, there were 60 982 cases of cervical, liver and stomach cancer in the study population, causing 36 582 deaths. The immigrant women had significantly higher liver (rate ratio [RR] 1.78, 95% confidence interval (CI) 1.03-3.06) and stomach cancer incidence (RR 1.68, CI 1.29-2.18), and stomach cancer mortality (RR 1.49, CI 1.17-1.92) than non-immigrant women. In the immigrant population, high education was related to lower incidence and mortality of studied cancers. The rate ratio of cervical cancer decreased with duration of residence and increased with rising age at immigration. CONCLUSION: Due to the increased incidence and mortality of infection-related cancers and changes in cancer patterns by age at immigration and duration of residence, attention should be paid to targeted health care services for immigrants. Special efforts should be given to women who have spent their youth in high-risk areas.

An overview of cervical cancer epidemiology and prevention in the Baltic States.

AIMS: To inform future Baltic States-specific policy analyses, we aimed to provide an overview of cervical cancer epidemiology and existing prevention efforts in Estonia, Latvia and Lithuania. METHODS: A structured desk review: we compiled and summarized data on current prevention strategies, population demography and epidemiology (high risk human papillomavirus (HPV) prevalence and cervical cancer incidence and mortality over time) for each Baltic State by reviewing published literature and official guidelines, performing registry-based analyses using secondary data and having discussions with experts in each country. RESULTS: We observed important similarities in the three Baltic States: high burden of the disease (high incidence and mortality of cervical cancer, changes in TNM (Classification of Malignant Tumors) stage distribution towards later stage at diagnosis), high burden of high-risk HPV in general population and suboptimal implementation of the preventive strategies as low screening and HPV vaccination coverage. CONCLUSIONS: Cervical cancer remains a substantial health problem in the region and the efforts in addressing barriers by implementing a four-step plan for elimination cervical cancer in Europe should be made. This goal is achievable through evidence-based steps in four key areas: vaccination, screening, treatment, and public awareness.

Matrix factorization for the reconstruction of cervical cancer screening histories and prediction of future screening results.

BACKGROUND: Mass screening programs for cervical cancer prevention in the Nordic countries have strongly reduced cancer incidence and mortality at the population level. An alternative to the current mass screening is a more personalised screening strategy adapting the recommendations to each individual. However, this necessitates reliable risk prediction models accounting for disease dynamics and individual data. Herein we propose a novel matrix factorisation framework to classify females by the time-varying risk of being diagnosed with cervical cancer. We cast the problem as a time-series prediction model where the data from females in the Norwegian screening population are represented as sparse vectors in time and then combined into a single matrix. Using novel temporal regularisation and discrepancy terms for the cervical cancer screening context, we reconstruct complete screening profiles from this scarce matrix and use these to predict the next exam results indicating the risk of cervical cancer. The algorithm is validated on both synthetic and registry screening data by measuring the probability of agreement (PoA) between Kaplan-Meier estimates. RESULTS: In numerical experiments on synthetic data, we demonstrate that the novel regularisation and discrepancy term can improve the data reconstruction ability as well as prediction performance over varying data scarcity. Using a hold-out set of screening data, we compare several numerical models and find that the proposed framework attains the strongest PoA. We observe strong correlations between the empirical survival curves from our method and the hold-out data, and evaluate the ability of our framework to predict the females' next results for up to five years ahead in time using only their current screening histories as input. CONCLUSIONS: We have proposed a matrix factorization model for predicting future screening results and evaluated its performance in a female cohort to demonstrate the potential for developing prediction models for more personalized cervical cancer screening.

HPV self-sampling among long-term non-attenders to cervical cancer screening in Norway: a pragmatic randomised controlled trial.

BACKGROUND: Cervical cancer screening participation is suboptimal in most settings. We assessed whether human papillomavirus (HPV) self-sampling may increase screening participation among long-term non-attenders in Norway. METHODS: A pragmatic randomised controlled trial with participation as the primary outcome was initiated in the national cervical screening programme in March 2019. A random sample of 6000 women aged 35-69 years who had not attended screening for at least 10 years were randomised 1:1:1 to receive either (i) a reminder to attend regular screening (control), (ii) an offer to order a self-sampling kit (opt-in) for HPV testing or (iii) a self-sampling kit unsolicited (send-to-all) for HPV testing. RESULTS: Total participation was 4.8%, 17.0% and 27.7% among control, opt-in and send-to-all (P < 0.0001; participation difference (%) send-to-all vs. control: 22.9 (95%CI: 20.7, 25.2); opt-in vs. control: 12.3 (95%CI: 10.3, 14.2); send-to-all vs. opt-in: 10.7 (95% CI: 8.0, 13.3)). High-risk HPV was detected in 11.5% of self-samples and 9.2% of clinician-collected samples (P = 0.40). Most women (92.5%) who returned a positive self-sample attended the clinic for triage testing. Of the 933 women screened, 33 (3.5%) had CIN2 + (1.1%, 3.7%, 3.8% among control, opt-in, and send-to-all, respectively), and 11 (1.2%) had cervical cancer (0%, 1.2%, 1.3% among control, opt-in, send-to-all, respectively). CONCLUSION: Opt-in and send-to-all self-sampling increased screening participation among long-term, higher-risk non-attenders. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT03873376.

Regional differences in cervical cancer incidence and associated risk behaviors among Norwegian women: a population-based study.

BACKGROUND: Cervical cancer incidence is influenced by screening and risk factors in the population. The main risk factor for cervical cancer is sexually transmitted human papillomavirus (HPV), which is sexually transmitted and thus associated with sexual behavior. Smoking, parity and hormonal contraceptive use may also be associated with cervical cancer risk. We compared incidence, screening coverage and risk behaviors for cervical cancer between health regions in Norway. METHODS: We obtained data on incidence of cervical cancer among Norwegian women during 1992-2016 and data on screening coverage from the Cancer Registry of Norway. We obtained data on sexual behavior and smoking from a population-based survey of 16,575 Norwegian women who were 18-45 years old in 2005. RESULTS: Cervical cancer incidence was higher in the northern and southeastern region than in the middle and western region (range in incidence per 100,000 person-years during 1992-2016; north: 10.5 to 14.6; southeast: 9.3 to 12.9; mid: 6.8 to 9.5; west: 8.4 to 10.0). The incidence decreased modestly in the north (average annual percentage change (95% confidence interval) - 1.0 (- 1.2 to - 0.7)) and southeast (- 0.7 (- 1.0 to - 0.3)), but did not change significantly in the mid (- 0.3 (- 1.0 to 0.4)) and west (- 0.3 (- 0.6 to 0.0)). Compared to the national average, women in the north had earlier sexual debut, more partners and higher prevalence of ever having had a sexually transmitted infection (STI), while the opposite was observed among women in the west. Women in the middle and southeastern regions tended to be similar to the national average for sexual behaviors. Although less pronounced, the prevalence of smoking showed regional patterns similar to that observed for sexual behaviors, while ever-use of hormonal contraceptives and cervical screening coverage was similar between regions. CONCLUSIONS: There were regional differences in cervical cancer incidence during the era of nationally organized cervical screening in Norway. To some extent, these differences corresponded to regional differences in risk behavior for cervical cancer in the Norwegian female population.

Elimination of HPV-associated oropharyngeal cancers in Nordic countries.

Incidence of human papillomavirus (HPV, most notably HPV type 16) associated oropharyngeal squamous cell carcinoma (OPSCC) among middle-aged (50-69 year-old) males has tripled in four high income Nordic countries (Denmark, Finland, Norway and Sweden) over the last 30 years. In Finland and Sweden, this increase was preceded by an HPV16 epidemic in fertile-aged populations in the 1980's. The recent implementation of school-based prophylactic HPV vaccination in early adolescent boys and girls will gradually decrease the incidence, and eventually eliminate the HPV-associated OPSCCs (especially tonsillar and base of tongue carcinomas) in the Nordic countries. However, beyond the adolescent and young adult birth cohorts vaccinated, there are approximately 50 birth cohorts (born in 1995 or before) that would benefit from screening for HPV-associated OPSCC. This article reviews the need, prerequisites, proof-of-concept trial and prospects of preventing HPV-associated OPSCC in the Nordic countries.

Impact and cost-effectiveness of strategies to accelerate cervical cancer elimination: A model-based analysis.

Following the global call for action by the World Health Organization to eliminate cervical cancer (CC), we evaluated how each CC policy decision in Norway influenced the timing of CC elimination, and whether introducing nonavalent human papillomavirus (HPV) vaccine would accelerate elimination timing and be cost-effective. We used a multi-modeling approach that captured HPV transmission and cervical carcinogenesis to estimate the CC incidence associated with six past and future CC prevention policy decisions compared with a pre-vaccination scenario involving 3-yearly cytology-based screening. Scenarios examined the introduction of routine HPV vaccination of 12-year-old girls with quadrivalent vaccine in 2009, a temporary catch-up program for females aged up to 26 years in 2016-2018 with bivalent vaccine, the universal switch to bivalent vaccine in 2017, expansion to include 12-year-old boys in 2018, the switch from cytology- to HPV-based screening for women aged 34-69 in 2020, and the potential switch to nonavalent vaccine in 2021. Introducing routine female vaccination in 2009 enabled elimination to be achieved by 2056 and prevented 17,300 cases. Cumulatively, subsequent policy decisions accelerated elimination to 2039. According to our modeling assumptions, switching to the nonavalent vaccine would not be considered 'good value for money' at relevant cost-effectiveness thresholds in Norway unless the incremental cost was $19 per dose or less (range: $17-24) compared to the bivalent vaccine. CC control policies implemented over the last decade in Norway may have accelerated the timeframe to elimination by more than 17 years and prevented over 23,800 cases by 2110.

Real-world data on cervical cancer risk stratification by cytology and HPV genotype to inform the management of HPV-positive women in routine cervical screening.

BACKGROUND: HPV16/18 detection may improve cervical cancer risk stratification and better guide which HPV-positive women warrant immediate colposcopy/biopsy. We estimated risks of cervical precancer and cancer by HPV genotype and cytology during the implementation phase of primary HPV testing in Norway. METHODS: A total of 3111 women, aged 34-69 years, testing HPV-positive at baseline and undergoing cytology testing from February 2015 to April 2018 had data available for analysis. Risk estimates with 95% confidence intervals (95%CIs) of cervical intraepithelial neoplasia grade 3 or more severe (CIN3+) were estimated for cytology results and HPV genotypes (HPV16, HPV18, and other high-risk HPV). RESULTS: CIN3+ risks were higher for HPV16/18 than other high-risk HPV genotypes. Among women with any cytologic abnormality [atypical squamous cells of undetermined significance or worse], immediate risks were 57.8% (95%CI = 53.0-62.6%) for HPV16, 40.2% (95%CI = 32.3-49.2%) for HPV18, and 31.4% (95%CI = 28.7-34.3%) for other high-risk HPV. Among those with normal cytology, CIN3+ risks were 19.9% (95%CI = 15.0-26.1%) for HPV16 positives, 10.8% (95%CI = 5.6-20.5%) for HPV18 positives, and 5.5% (95%CI = 4.2-7.1%) for other high-risk HPV. CONCLUSIONS: The benefits and harms of managing women based on HPV positivity and cytology results can be better balanced by inclusion of HPV genotyping in screening and choosing more conservative management for other high-risk HPV compared to HPV16/18.

A hidden Markov model for population-level cervical cancer screening data.

The Cancer Registry of Norway has been administrating a national cervical cancer screening program since 1992 by coordinating triennial cytology exam screenings for the female population between 25 and 69 years of age. Up to 80% of cancers are prevented through mass screening, but this comes at the expense of considerable screening activity and leads to overtreatment of clinically asymptomatic precancers. In this article, we present a continuous-time, time-inhomogeneous hidden Markov model which was developed to understand the screening process and cervical cancer carcinogenesis in detail. By leveraging 1.7 million individual's multivariate time-series of medical exams performed over a 25-year period, we simultaneously estimate all model parameters. We show that an age-dependent model reflects the Norwegian screening program by comparing empirical survival curves from observed registry data and data simulated from the proposed model. The model can be generalized to include more detailed individual-level covariates as well as new types of screening exams. By utilizing individual screening histories and covariate data, the proposed model shows potential for improving strategies for cancer screening programs by personalizing recommended screening intervals.

Factors associated with condom use during sexual intercourse with a new partner among Scandinavian women.

In this population-based, cross-sectional questionnaire study among 18-45-year-old women from Denmark, Sweden, and Norway conducted during 2011-2012 we examine factors associated with using condoms with a new partner. Condom use with a new partner was assessed among 6202 women having had a new partner in the recent six months. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for the associations between sociodemographic and lifestyle factors, and sexual behavior, respectively, and condom use with a new partner using a logistic regression model. Always/almost always ("always") condom use served as the reference category in all analyses and was compared with sometimes/rarely ("sometimes") and never use in two separate analyses. Overall, respectively 36.3%, 26%, and 37.7% reported always, sometimes, or never condom use with a new partner. Married/cohabiting were more likely than single women to never (OR = 2.50, 95% CI: 2.07-3.02) or sometimes (OR = 1.30; 95% CI 1.04-1.62) use condoms with recent new partners. Increasing number of new partners in the recent six months was also associated with condom use with a new partner (never: OR for ≥3 partners = 0.56; 95% CI: 0.47-0.67; sometimes: OR for ≥3 partners = 1.64; 95% CI: 1.38-1.94). Furthermore, women reporting early age at first sexual intercourse, no contraception at first intercourse, or not being vaccinated against human papillomavirus used condoms with new partners less frequently. These findings may suggest that continued awareness about the risk of contracting sexually transmitted infections when practicing condomless sex is important.

Emergency contraceptive pill use among women in Denmark, Norway and Sweden: Population-based survey.

INTRODUCTION: Emergency contraceptive pill (ECP) use is reported to have increased in several countries over time. In this multi-country population-based questionnaire study, we aimed to describe the patterns of ECP use and identify factors associated with its use. MATERIAL AND METHODS: In 2011-2012, women aged 18-45 years were randomly selected from national registers in Denmark, Norway and Sweden and invited to respond to questions related to lifestyle and contraceptive use. We used generalized logistic models to estimate odds ratios (ORs) and 95% confidence intervals (CI) comparing women who had used ECP with women who had never used ECP. RESULTS: Of the 45 445 women, 33.9% (Denmark = 32.3%, Norway = 35.1%, Sweden = 34.6%) had used ECP at least once in their lifetime. Among ECP users, 15.8% had used ECP within the last year and 50.0% had used ECP more than once in their life. After adjusting for country, age at response and response type, ECP use was associated with higher education (OR 2.09, 95% CI 1.54-2.84) and being single, divorced or widowed (OR 3.17, 95% CI 2.87-3.49). Binge drinking and smoking increased the odds of ECP use. Furthermore, early age at first intercourse (OR 1.29, 95% CI 1.08-1.55), having a new partner in the last 6 months (≥3 partners: OR 6.44, 95% CI 5.46-7.60) and lack of condom use with a recent new partner (OR 1.42, 95% CI 1.22-1.66) were found to be associated with ECP use. CONCLUSIONS: Our study shows that ECP use is common among Scandinavian women. Higher education and being single were associated with increased odds of ECP use. Risk behaviors such as smoking and early age at first sex were also associated with increased odds of ECP use. Since ECP use is not protective against sexually transmitted infections, our findings highlight the need to encourage awareness and regular use of condoms to prevent sexually transmitted diseases in women.

Age at first intercourse, number of partners and sexually transmitted infection prevalence among Danish, Norwegian and Swedish women: estimates and trends from nationally representative cross-sectional surveys of more than 100 000 women.

INTRODUCTION: Sexual behavior at the population level impacts on public health. Recent representative sexual behavior data are lacking. MATERIAL AND METHODS: Cross-sectional surveys in 2005 and 2012 on women age 18-45 years randomly selected from the general population in Denmark (n = 40 804), Norway (n = 30 331) and Sweden (n = 32 114). RESULTS: Median (interquartile range) age at first intercourse was 16 (15-18) years in Denmark, 17 (16-18) years in Norway, and 17 (15-18) years in Sweden. Women in the most recent birth cohort had sexual debut at the lowest age, and were most likely to have sexual debut before the legal age of consent. Proportions with debut age ≤14 years among women born 1989-1994 vs 1971-1976, odds ratio (95% confidence interval) were: 18.4% vs 10.9%, 1.95 (1.74-2.18) in Denmark, 12.9% vs 6.3%, 2.38 (2.01-2.82) in Norway, 17.8% vs 11.4%, 1.75 (1.55-1.98) in Sweden. Median (interquartile range) number of lifetime sexual partners was 6 (3-10) in Denmark, 5 (2-10) in Norway, and 6 (3-11) in Sweden. The proportion of women reporting >10 sexual partners was also highest in the most recent survey. The percentage with odds ratio (95% confidence interval) in 2012 vs 2005 surveys were: 24.9% vs 22.8%, 1.13 (1.07-1.18) for Denmark; 23.8% vs 19.8%, 1.27 (1.19-1.34) for Norway; and 28.3% vs 23.8%, 1.31 (1.24-1.38) for Sweden. Similarly, the proportion of women reporting ever having had a sexually transmitted infection among women age <30 years were: 29.4% vs 26.4%, 1.21 (1.13-1.31) in Denmark, 28.9% vs 25.0%, 1.20 (1.10-1.31) in Norway, and 29.4% vs 22.2%, 1.45 (1.33-1.58) in Sweden. CONCLUSIONS: Scandinavian women reported lower age at first intercourse in younger birth cohorts. Moreover, they reported more lifetime sexual partners and a higher prevalence of ever having a sexually transmitted infection in 2012 than in 2005. Our findings may inform the interpretation of trends in outcomes associated with sexual health, and public health policies.

Recent increase in incidence of cervical precancerous lesions in Norway: Nationwide study from 1992 to 2016.

We analysed patterns in the incidence of cervical intraepithelial neoplasia grades 2 and 3 (CIN2, CIN3) and adenocarcinoma in situ (AIS) by age and histology in 1992-2016 in Norway and described changes in screening tests. Incident cases of CIN2, CIN3, AIS and cervical cancer were identified in the Cancer Registry of Norway, as were all women with at least one screening test. The annual percentage change statistic was used to assess point estimates and changes in age-specific and age-standardised incidence rates (IR). Women aged 25-29 years had the highest incidence of cervical precancerous lesions (CIN2: 192.9/10, CIN3: 737.2/10, AIS: 32.5/105 in 2016). The IR of CIN2 increased for all screening ages (25-69 years) from 3.6% to 6.7% per year. CIN3 incidence increased by 1.6% (95% confidence interval [CI] 0.6-2.6) annually. A steep increase in AIS incidence was observed in all age groups (7.1% per year, 95% CI 5.3-8.8). Changes in screening tests and the histological verification of cervical precancerous lesions alone cannot explain the steady increase in incidence we observed over the 25-year study period, and increased exposure to human papillomavirus (HPV) likely plays a role. Age-appropriate treatment of screening-detected cervical precancerous lesions is needed for effective cervical cancer control while avoiding overtreatment and related health risks. In order to perform an appropriate harm-benefit evaluation of cervical cancer control efforts, detailed information on screening technology and background risks, including HPV vaccination status, is needed to create optimal public health policy.

Bayesian multitask learning regression for heterogeneous patient cohorts.

Multitask learning (MTL) leverages commonalities across related tasks with the aim of improving individual task performance. A key modeling choice in designing MTL models is the structure of the tasks' relatedness, which may not be known. Here we propose a Bayesian multitask learning model that is able to infer the task relationship structure directly from the data. We present two variations of the model in terms of a priori information of task relatedness. First, a diffuse Wishart prior is placed on a task precision matrix so that all tasks are assumed to be equally related a priori. Second, a Bayesian graphical LASSO prior is used on the task precision matrix to impose sparsity in the task relatedness. Motivated by machine learning applications in the biomedical domain, we emphasize interpretability and uncertainty quantification in our models. To encourage model interpretability, linear mappings from the shared input spaces to task-dependent output spaces are used. To encourage uncertainty quantification, conjugate priors are used so that full posterior inference is possible. Using synthetic data, we show that our model is able to recover the underlying task relationships as well as features jointly relevant for all tasks. We demonstrate the utility of our model on three distinct biomedical applications: Alzheimer's disease progression, Parkinson's disease assessment, and cervical cancer screening compliance. We show that our model outperforms Single Task (STL) models in terms of predictive performance, and performs better than existing MTL methods for the majority of the scenarios.

A 12-Year Follow-up on the Long-Term Effectiveness of the Quadrivalent Human Papillomavirus Vaccine in 4 Nordic Countries.

Background: The long-term effectiveness of the quadrivalent human papillomavirus (qHPV) vaccine was assessed by monitoring the combined incidence of cervical intraepithelial neoplasia (CIN2, CIN3), adenocarcinoma in situ (AIS), and cervical cancer related to HPV16 or HPV18. Methods: Women from Nordic countries of Denmark, Iceland, Norway, and Sweden who received a 3-dose regimen of the qHPV vaccine in the beginning of FUTURE II (Females United to Unilaterally Reduce Endo/Ectocervical Disease; V501-015, base study NCT00092534) are followed through different national registries. Effectiveness analyses were conducted approximately 2 years following completion of the base study and occur approximately every 2 years thereafter for 10 years (ie, 14 years from day 1 of the base study). Vaccine effectiveness against HPV16/18-related CIN2 or worse (CIN2+) was estimated by comparing the observed incidence with the expected incidence of CIN2+ in an unvaccinated cohort using historical registry data. Results: In the per-protocol population (2084 women) analysis of effectiveness after the first 12 years, there were no breakthrough cases of HPV16/18 CIN2+ after 9437 person- years of follow-up. Statistical power was sufficient to conclude that qHPV vaccine effectiveness remains above 90% for at least 10 years. The number of person-years during the follow-up interval of 10-12 years is continuing to accrue and shows a trend toward continuing effectiveness of the vaccine during that period. Conclusion: The qHPV vaccine shows continued protection in women through at least 10 years, with a trend for continued protection through 12 years of follow-up. Clinical Trials Registration: NCT00092534. Study Identification: V501-015.