Predictable changes in the accuracy of human papillomavirus tests after vaccination: review with implications for performance monitoring in cervical screening.

Vaccination against human papillomavirus (HPV) is changing the performance of cytology as a cervical screening test, but its effect on HPV testing is unclear. We review the effect of HPV16/18 vaccination on the epidemiology and the detection of HPV infections and high-grade cervical lesions (CIN2+) to evaluate the likely direction of changes in HPV test accuracy. The reduction in HPV16/18 infections and cross-protection against certain non-16/18 high-risk genotypes, most notably 31, 33, and/or 45, will likely increase the test's specificity but decrease its positive predictive value (PPV) for CIN2+. Post-vaccination viral unmasking of non-16/18 genotypes due to fewer HPV16 co-infections might reduce the specificity and the PPV for CIN2+. Post-vaccination clinical unmasking exposing a higher frequency of CIN2+ related to non-16/18 high-risk genotypes is likely to increase the specificity and the PPV of HPV tests. The effect of HPV16/18 vaccination on HPV test sensitivity is difficult to predict based on these changes alone. Programmes relying on HPV detection for primary screening should monitor the frequency of false-positive and false-negative tests in vaccinated (younger) vs. unvaccinated (older) cohorts, to assess the outcomes and performance of their service.

Managing an extension of screening intervals: Avoiding boom and bust in health care workloads.

Extending screening intervals in ongoing cancer screening programmes can lead to challenging year-on-year variations in the number of screening tests. We explored how such variation could be diminished with a managed transition to the extended interval. We defined three extension scenarios: immediate extension for the entire target population; stepped transition by birth cohort; and gradual transition by reducing the number of available screening appointments. These were compared to a situation in which the interval remains unchanged in a demographic model covering a 15-year period. The model was populated with observed parameters from England, a real-world setting recommending cervical screening with 3-year intervals at age 25-49 and 5-year intervals at age 50-64. Informed by typical changes currently considered by several European programmes including the programme in England, we explored the effect on screening test numbers of an extension of the 3-year interval to 5 years for women younger than 50. All three extension scenarios resulted in similar cumulative numbers of screening tests, which were about 30% lower compared to a situation in which the interval would remain unchanged. However, the year-on-year variation in the number of screening tests varied between the scenarios. This variation was around 4-fold for the immediate scenario. In the stepped scenario, the yearly numbers could differ by around 20%, whereas in the gradual scenario they were virtually constant. A managed interval extension, transitioning different groups of the target population at different times, can substantially reduce the yearly variation in screening workload without increasing the total number of screening tests in the long term.

Widening the offer of human papillomavirus self-sampling to all women eligible for cervical screening: Make haste slowly.

Self-collection of samples for human papillomavirus (HPV) testing has the potential to increase the uptake of cervical screening among underscreened women and will likely form a crucial part of the WHO's strategy to eliminate cervical cancer by 2030. In high-income countries with long-standing, organised cervical screening programmes, self-collection is increasingly becoming available as a routine offer for women regardless of their screening histories, including under- and well-screened women. For these contexts, a validated microsimulation model determined that adding self-collection to clinician collection is likely to be cost-effective on the condition that it meets specific thresholds relating to (1) uptake and (2) sensitivity for the detection of high-grade cervical intraepithelial neoplasia (CIN2+). We used these thresholds to review the 'early-adopter' programme-level evidence with a mind to determine how well and how consistently they were being met. The available evidence suggested some risk to overall programme performance in the situation where low uptake among underscreened women was accompanied by a high rate of substituting clinician sampling with self-collection among well-screened women. Risk was further compounded in a situation where the slightly reduced sensitivity of self-sampling vs clinician sampling for the detection of CIN2+ was accompanied with lack of adherence to a follow-up triage test that required a clinician sample. To support real-world programmes on their pathways toward implementation and to avoid HPV self-collection being introduced as a screening measure in good faith but with counterproductive consequences, we conclude by identifying a range of mitigations and areas worthy of research prioritisation.

Concurrent participation in breast, cervical, and colorectal cancer screening programmes in Denmark: A nationwide registry-based study.

Women in Denmark are invited to breast, cervical, and colorectal cancer screening in their fifties and sixties. We determined the patterns of concurrent participation in the three programmes. Participation in organised cancer screening was determined using the highly complete Danish population and health care registers for all women aged 53-65 years on 31 March 2018 who continuously resided in Denmark since 1 April 2012. Data were linked using unique personal identification numbers. We studied overall and cancer-specific proportions of women undergoing screening for all three, two, one, and none of the cancers. Among all 468,507 women, 406,306 (87%) participated in breast, 345,768 (74%) in cervical, and 316,496 (68%) in colorectal cancer screening. Despite high participation, only 255,698 (55%) women were screened for all three cancers, while 123,469 (26%) were screened for two, 54,538 (12%) for one, and 34,802 (7%) were not screened for any cancer. Cancer-specific patterns were highly heterogeneous across the population but changed little after accounting for women's medical history. A significant proportion of women who are screened for a specific cancer remain unscreened for other cancers. The consistency of these data at the international level requires a reconsideration of invitational practices for organised screening.

Acceleration of cervical cancer diagnosis with human papillomavirus testing below age 30: Observational study.

Several international cervical screening guidelines advise against using high-risk human papillomavirus (HR-HPV) testing in women younger than 30. The rationale for this in young women, lies in the potential for additional detection of both low-grade and high-grade cervical intraepithelial neoplasia (CIN) leading to unnecessary treatments without reducing the burden of cervical cancer. We studied 56 544 women screened at 24 to 29 with HR-HPV testing and 116 858 screened with liquid-based cytology (LBC) in the English HPV screening pilot. They were compared to 528 460 women screened at the age of 30 to 49. We studied the detection of cervical cancer and CIN2/3 across two consecutive screening rounds 3 years apart. At 24 to 29, a positive HR-HPV test detected more cases of cervical cancer in the prevalence round than did a positive LBC test (1.36/1000 screened vs 0.82/1000, ORadj : 1.61, 95% CI: 1.18-2.19). In women with a negative HR-HPV test, cervical cancer was diagnosed before or at the incidence round in 0.07/1000. After a negative LBC test, cancer detection reached 0.47/1000 and 40% of these cases were diagnosed at FIGO stage IB+. HR-HPV testing increased the detection of CIN2/3 diagnoses in two consecutive rounds combined by 30% (71.9/1000 vs 55.2/1000). The patterns of detection of cervical cancer and CIN2/3 were almost identical at older ages. These data support using HR-HPV testing for screening of women younger than 30, which not only accelerates the diagnosis of cervical cancer but leads to a similar relative increase in CIN2/3 diagnosis to that found in women aged 30 to 49.

The impact of catch-up bivalent human papillomavirus vaccination on cervical screening outcomes: an observational study from the English HPV primary screening pilot.

BACKGROUND: In England, bivalent vaccination (Cervarix) against high-risk human papillomavirus (HR-HPV) genotypes 16/18 was offered in a population-based catch-up campaign in 2008-2010 to girls aged 14-17 years. These women are now entering the national cervical screening programme. We determined the impact of catch-up bivalent vaccination on their screening outcomes. METHODS: We studied the overall and genotype-specific screening outcomes in 108,138 women aged 24-25 (offered vaccination) and 26-29 years (not offered vaccination) included in the English HPV screening pilot between 2013 and 2018. RESULTS: At 24-25 years, the detection of high-grade cervical intraepithelial neoplasia (CIN2+) associated with HPV16/18 decreased from 3 to 1% (p < 0.001), with estimated vaccine effectiveness of 87% (95% CI: 82-91%). The detection of any CIN2+ halved from 6 to 3% (p < 0.001), with an estimated vaccine effectiveness of 72% (95% CI: 66-77%). The positive predictive value of a colposcopy for CIN2+ decreased for both low-grade (p < 0.001) and high-grade (p = 0.02) abnormalities on triage cytology. The decreases in screen-detected abnormalities at age 26-29 were of a substantially smaller magnitude. CONCLUSIONS: These data confirm high effectiveness of bivalent HPV vaccination delivered through a population-based catch-up campaign in England. These findings add to the rationale for extending screening intervals for vaccinated cohorts.

Age-specific outcomes from the first round of HPV screening in unvaccinated women: Observational study from the English cervical screening pilot.

OBJECTIVE: To report detailed age-specific outcomes from the first round of an English pilot studying the implementation of high-risk human papillomavirus (HR-HPV) testing in primary cervical screening. DESIGN: Observational study with screening in 2013-2016, followed by two early recalls and/or colposcopy until the end of 2019. SETTING: Six NHS laboratory sites. POPULATION: A total of 1 341 584 women undergoing screening with HR-HPV testing or liquid-based cytology (LBC). METHODS: Early recall tests and colposcopies were recommended, depending on the nature of the screening-detected abnormality. MAIN OUTCOME MEASURES: We reported standard screening process indicators, e.g. proportions with an abnormality, including high-grade cervical intraepithelial neoplasia (CIN2+) or cancer, and the positive predictive value (PPV) of colposcopy for CIN2+, by screening test and age group. RESULTS: Among unvaccinated women screened with HR-HPV testing at age 24-29 years, 26.9% had a positive test and 10.4% were directly referred to colposcopy following cytology triage, with a PPV for CIN2+ of 47%. At 50-64 years of age, these proportions were much lower: 5.3%, 1.2% and 27%, respectively. The proportions of women testing positive for HR-HPV without cytological abnormalities, whose early recall HR-HPV tests returned negative results, were similar across the age spans: 54% at 24-29 years and 55% at 50-64 years. Two-thirds of infections at any age were linked to non-16/18 genotypes. Among women with CIN2, CIN3 or cervical cancer, however, the proportion of non-16/18 infections increased with age. As expected, the detection of abnormalities was lower following screening with LBC. CONCLUSIONS: These data provide a reliable reference for future epidemiological studies, including those concerning the effectiveness of HPV vaccination. TWEETABLE ABSTRACT: Data from the English pilot study provide a comprehensive overview of abnormalities detected through HPV screening.

Supporting the implementation of new healthcare technologies by investigating generalisability of pilot studies using area-level statistics.

BACKGROUND: Implementation of new technologies into national health care systems requires careful capacity planning. This is sometimes informed by data from pilot studies that implement the technology on a small scale in selected areas. A critical consideration when using implementation pilot studies for capacity planning in the wider system is generalisability. We studied the feasibility of using publicly available national statistics to determine the degree to which results from a pilot might generalise for non-pilot areas, using the English human papillomavirus (HPV) cervical screening pilot as an exemplar. METHODS: From a publicly available source on population indicators in England ("Public Health Profiles"), we selected seven area-level indicators associated with cervical cancer incidence, to produce a framework for post-hoc pilot generalisability analysis. We supplemented these data by those from publicly available English Office for National Statistics modules. We compared pilot to non-pilot areas, and pilot regimens (pilot areas using the previous standard of care (cytology) vs. the new screening test (HPV)). For typical process indicators that inform real-world capacity planning in cancer screening, we used standardisation to re-weight the values directly observed in the pilot, to better reflect the wider population. A non-parametric quantile bootstrap was used to calculate 95% confidence intervals (CI) for differences in area-weighted means for indicators. RESULTS: The range of area-level statistics in pilot areas covered most of the spectrum observed in the wider population. Pilot areas were on average more deprived than non-pilot areas (average index of multiple deprivation 24.8 vs. 21.3; difference: 3.4, 95% CI: 0.2-6.6). Participants in HPV pilot areas were less deprived than those in cytology pilot areas, matching area-level statistics. Differences in average values of the other six indicators were less pronounced. The observed screening process indicators showed minimal change after standardisation for deprivation. CONCLUSIONS: National statistical sources can be helpful in establishing the degree to which the types of areas outside pilot studies are represented, and the extent to which they match selected characteristics of the rest of the health care system ex-post. Our analysis lends support to extrapolation of process indicators from the HPV screening pilot across England.

Attendance at early recall and colposcopy in routine cervical screening with human papillomavirus testing.

Attendance at early recall and colposcopy is crucial to attaining the benefits of primary high-risk human papillomavirus (HR-HPV)-based screening. Within the English HPV pilot, we analysed deprivation- and age-related patterns of attendance at colposcopy and 12- and 24-month early recall of HR-HPV positive women screened in 2013 to 2015 (N = 36 466). We fitted logistic regression models for adjusted odds ratios (OR). Despite high overall attendance, area deprivation had a small but significant impact at both early recalls, for example, attendance at 24 months was 86.3% and 83.0% in less vs more deprived areas, respectively (ORadj : 0.76; 95% CI: 0.67-0.87). Older women (≥30 years) were more likely to attend early recall than younger women (<30 years), for example, attendance at 24 months was 86.1% vs 82.3%, respectively (ORadj : 1.32, 95% CI: 1.16-1.51). Most women attended colposcopy following a baseline referral, with 96.9% attendance among more deprived and 97.8% among less deprived areas (ORadj : 0.70; 95% CI: 0.55-0.88). Differences in colposcopy attendance by deprivation level at 12 and 24 months were of approximately the same magnitude. In conclusion, attendance at early recall and colposcopy was reassuringly high. Although there were statistically significant differences by deprivation and age group, these were small in absolute terms.

Recovery strategies following COVID-19 disruption to cervical cancer screening and their impact on excess diagnoses.

BACKGROUND: The COVID-19 pandemic has disrupted cervical cancer screening services. Assuming increases to screening capacity are unrealistic, we propose two recovery strategies: one extends the screening interval by 6 months for all and the other extends the interval by 36/60 months, but only for women who have already missed being screened. METHODS: Using routine statistics from England we estimate the number of women affected by delays to screening. We used published research to estimate the proportion of screening age women with high-grade cervical intraepithelial neoplasia and progression rates to cancer. Under two recovery scenarios, we estimate the impact of COVID-19 on cervical cancer over one screening cycle (3 years at ages 25-49 and 5 years at ages 50-64 years). The duration of disruption in both scenarios is 6 months. In the first scenario, 10.7 million women have their screening interval extended by 6 months. In the second, 1.5 million women (those due to be screened during the disruption) miss one screening cycle, but most women have no delay. RESULTS: Both scenarios result in similar numbers of excess cervical cancers: 630 vs. 632 (both 4.3 per 100,000 women in the population). However, the scenario in which some women miss one screening cycle creates inequalities-they would have much higher rates of excess cancer: 41.5 per 100,000 delayed for screened women compared to those with a 6-month delay (5.9 per 100,000). CONCLUSION: To ensure equity for those affected by COVID-19 related screening delays additional screening capacity will need to be paired with prioritising the screening of overdue women.

Variations in pathways and resource use in follow-up after abnormal mammography screening: a nationwide register-based study.

PURPOSE: Mammography screening reduces breast cancer mortality, but a successful screening programme depends on both high participation and a sufficient follow-up of abnormalities. This study investigated patterns of follow-up after abnormal screening mammography in Denmark, and whether the variation was associated with health care resource use. METHODS: We included 19,458 women aged 50-69 years with an abnormal screening mammography during a 3-year period of 2014-2016. Women were followed until the end of 2018. Their follow-up pathway was categorized in terms of the timeliness, appropriateness (i.e. whether all recommended diagnostic tests were utilized), and the ratio of benign vs. malignant surgeries. Further, we estimated health care resource use including post-diagnostic imaging and surgery procedures. RESULTS: Ninety-seven percent of women had a diagnostic follow-up test within 6 months and 94% of those had diagnostic procedures in accordance with the recommendations. The proportion with timely follow-up (i.e. within 1 month) was 83%, but varied significantly between administrative regions (p < 0.001), and also between women with a screen-detected cancer and those with a false-positive mammogram (87% vs. 81%, p < 0.001). The ratio between having a benign versus a malignant surgery was 1:8, but it varied depending on which tests were used for diagnosis. The average number of procedures was, generally, in accordance with the recommendations. CONCLUSION: In most cases, follow-up after abnormal screening mammography followed national recommendations. We nevertheless found that this was not always the case in certain subgroups and administrative regions.

Gaps between recommendations and their implementation: A register-based study of follow-up after abnormalities in cervical cancer screening.

Follow-up after screen-detected abnormalities is crucial for the success of cervical cancer screening programs but is usually not closely monitored in official screening statistics. We determined how the follow-up deviated from the recommendations in the Danish organized program. Using Danish nationwide population-based registers, the follow-up pathways of 60,199 women aged 23-59 with non-negative screening samples from 2012 to 2014 were mapped until end of 2018. We studied the timeliness and appropriateness of follow-up tests after cervical cytology screening and the total resource use in accordance with the national recommendations. Regression analyses were used to determine variations in adherence according to age, provider type, region, and history of abnormalities. Among women referred for immediate colposcopy, 91.3% (95% CI: 90.9%-91.6%) attended within four months as recommended, whereas up to about half of the women with a recommendation for a repeat test received this test either too early or very late. Overall, only 43% (95% CI: 42.9%-43.7%) of women with non-negative screening tests received the recommended follow-up, whereas 18% (95% CI: 17.6%-18.2%) received more than was recommended, 35% (95% CI: 34.4%-35.1%) received some follow-up but less than recommended and 4% (95% CI: 3.9%-4.2%) were not followed up at all. These proportions varied by screening diagnosis, woman's age, type of health care provider, region, and history of abnormalities. On average, women underwent more tests of each type than recommended by the guidelines. Deviations from follow-up recommendations are very frequent even in organized cervical screening programs and should be routinely monitored by screening program statistics.

Impact of disruptions and recovery for established cervical screening programs across a range of high-income country program designs, using COVID-19 as an example: A modelled analysis.

COVID-19 has disrupted cervical screening in several countries, due to a range of policy-, health-service and participant-related factors. Using three well-established models of cervical cancer natural history adapted to simulate screening across four countries, we compared the impact of a range of standardised screening disruption scenarios in four countries that vary in their cervical cancer prevention programs. All scenarios assumed a 6- or 12-month disruption followed by a rapid catch-up of missed screens. Cervical screening disruptions could increase cervical cancer cases by up to 5-6%. In all settings, more than 60% of the excess cancer burden due to disruptions are likely to have occurred in women aged less than 50 years in 2020, including settings where women in their 30s have previously been offered HPV vaccination. Approximately 15-30% of cancers predicted to result from disruptions could be prevented by maintaining colposcopy and precancer treatment services during any disruption period. Disruptions to primary screening had greater adverse effects in situations where women due to attend for screening in 2020 had cytology (vs. HPV) as their previous primary test. Rapid catch-up would dramatically increase demand for HPV tests in 2021, which it may not be feasible to meet because of competing demands on the testing machines and reagents due to COVID tests. These findings can inform future prioritisation strategies for catch-up that balance potential constraints on resourcing with clinical need.

16/18 genotyping in triage of persistent human papillomavirus infections with negative cytology in the English cervical screening pilot.

BACKGROUND: In the English pilot of primary cervical screening with high-risk human papillomavirus (HR-HPV), we exploited natural viral clearance over 24 months to minimise unnecessary referral of HR-HPV+ women with negative cytology. Three laboratories were permitted to use 16/18 genotyping to select women for referral at 12-month recall. We estimated the clinical impact of this early genotyping referral. METHODS: The observed numbers of women referred to colposcopy and with detected high-grade cervical intraepithelial neoplasia (CIN2+), and of women who did not attend early recall in the three laboratories were compared with those estimated to represent a situation without an early genotyping referral. The 95% confidence intervals (CI) for the differences between the protocols were calculated by using a parametric bootstrap. RESULTS: Amongst 127,238 screened women, 16,097 (13%) had HR-HPV infections. The genotyping protocol required 5.9% (95% CI: 4.4-7.7) additional colposcopies and led to a detection of 1.2% additional CIN2+ (95% CI: 0.6-2.0), while 2.3% (95% CI: 2.1-2.5) fewer HR-HPV+/cytology- women did not attend the early recall compared with the non-genotyping protocol. CONCLUSIONS: In a screening programme with high quality of triage cytology and high adherence to early recall,16/18 genotyping of persistent HPV infections does not substantially increase CIN2+ detection.

As you like it: How the same data can support manifold views of overdiagnosis in breast cancer screening.

Overdiagnosis estimates have varied substantially, causing confusion. The discussions have been complicated by the fact that population and study design have varied substantially between studies. To help assess the impact of study design choices on the estimates, we compared them on a single population. A cohort study from Funen County, Denmark, recently suggested little (∼1%) overdiagnosis. It followed previously screened women for up to 14 years after screening had ended. Using publically available data from Funen, we recreated the designs from five high-estimate, highly cited studies from various countries. Selected studies estimated overdiagnosis to be 25-54%. Their designs were adapted only to the extent that they reflect the start of screening in Funen in 1993. The reanalysis of the Funen data resulted in overdiagnosis estimates that were remarkably similar to those from the original high-estimate age-period studies, 21-55%. In additional analyses, undertaken to elucidate the effect of the individual components of the study designs, overdiagnosis estimates were more than halved after the most likely changes in the background risk were accounted for and decreased additionally when never-screened birth cohorts were excluded from the analysis. The same data give both low and high estimates of overdiagnosis, it all depends on the study design. This stresses the need for a careful scrutiny of the validity of the assumptions underpinning the estimates. Age-period analyses of breast cancer overdiagnosis suggesting very high frequencies of overdiagnosis rested on unmet assumptions. This study showed that overdiagnosis estimates should in the future be requested to adequately control for the background risk and include an informative selection of the studied population to achieve valid and comparable estimates of overdiagnosis.

Addition of ultrasound to mammography in the case of dense breast tissue: systematic review and meta-analysis.

BACKGROUND: Mammography is less effective in detecting cancer in dense than in fatty breasts. METHODS: We undertook a systematic search in PubMed to identify studies on women with dense breasts who underwent screening with mammography supplemented with ultrasound. A meta-analysis was undertaken on the proportion of cancers detected only by ultrasound, out of all screen-detected cancers, and the proportion of women with negative mammography who were referred for assessment following ultrasound screening. RESULTS: Twenty-nine studies satisfied our inclusion criteria. The proportion of total cancers detected only by ultrasound was 0.29 (95% CI: 0.27-0.31), consistent with an approximately 40% increase in the detection of cancers compared to mammography. In the studied populations, this translated into an additional 3.8 (95% CI: 3.4-4.2) screen-detected cases per 1000 mammography-negative women. About 13% (32/248) of cancers were in situ from 17 studies with information on this subgroup. Ultrasound approximately doubled the referral for assessment in three studies with these data. CONCLUSIONS: Studies have consistently shown an increased detection of breast cancer by supplementary ultrasound screening. An inclusion of supplementary ultrasound into routine screening will need to consider the availability of ultrasound and diagnostic assessment capacities.

Human papillomavirus self-sampling for screening nonattenders: Opt-in pilot implementation with electronic communication platforms.

In organized cervical screening programs, typically 25% of the invited women do not attend. The Copenhagen Self-sampling Initiative (CSi) aimed to gain experiences on participation among screening nonattenders in the Capital Region of Denmark. Here, we report on the effectiveness of different communication platforms used in the pilot with suggestions for strategies prior to a full-implementation. Moreover, an innovative approach using self-sampling brushes with unique radio frequency identification chips allowed for unprecedented levels patient identification safety. Nonattenders from the capital region of Denmark were identified via the organized national invitation module. Screening history was obtained via the nationwide pathology registry. Twenty-four thousand women were invited, and as an alternative to the regular communication platforms (letter and phone), women could request a home test via a mobile-friendly webpage. Instruction material and video-animation in several languages were made available online. Chi-square test was used to test differences. Out of all invited, 31.7% requested a home test, and 20% returned it to the laboratory. In addition, 10% were screened at the physician after receiving the invitation. Stratified by screening history, long-term unscreened women were less likely to participate than intermittently screened women (28% vs. 16%, p < 0.001). Of all contacts received, 64% (63-65) came via letter, and 31% (95CI: 30-32%) via webpage/mobile-app. Self-sampling was well-accepted among nonattenders. Adopting modern technology-based platforms into the current organized screening program would serve as a convenient communication method between health authority and citizens, allowing easy access for the citizen and reducing the work load in administrating self-sampling approaches.

Differential Detection of Human Papillomavirus Genotypes and Cervical Intraepithelial Neoplasia by Four Commercial Assays.

Laboratories now can choose from >100 human papillomavirus (HPV) assays for cervical screening. Our previous analysis based on the data from the Danish Horizon study, however, showed that four widely used assays, Hybrid Capture 2 (HC2), cobas, CLART, and Aptima, frequently do not detect the same HPV infections. Here, we determined the characteristics of the concordant samples (all four assays returning a positive HPV test result) and discordant samples (all other HPV-positive samples) in primary cervical screening at 30 to 65 years of age (n = 2,859) and in a concurrent referral population from the same catchment area (n = 885). HPV testing followed the manufacturers' protocols. Women with abnormal cytology were managed according to the routine recommendations. Cytology-normal/HPV-positive women were invited for repeated testing in 18 months. Screening history and histologically confirmed cervical intraepithelial neoplasia (CIN) in 2.5 years after the baseline testing were determined from the national pathology register. HPV-positive women undergoing primary screening having concordant samples were more likely to harbor high-risk infections and less likely to harbor only low-risk infections than women with discordant samples. Additionally, assay signal strengths were substantially higher in concordant samples. More than 80% of ≥CIN2 results were found for women with concordant samples, and no ≥CIN2 results were found when the infection was detected by only one assay. These patterns were similar in the referral population despite the younger age and higher number of HPV infections. HPV test result discordance identified a cluster of low-risk HPV infections that were hardly ever associated with high-grade CIN and, almost exclusively, represented false-positive screening findings.