Dental healthcare costs of children living in Amsterdam and associated socio-demographic characteristics.

OBJECTIVES: The aim of this study was to assess associations between socio-demographic characteristics and dental costs of children living in Amsterdam. Having incurred dental costs was an indicator for having visited the dentist. Having incurred low or high dental costs may indicate the type of dental care provided (periodic examination, preventive care or restorative treatment). METHODS: This study followed a cross-sectional, observational design. The research population contained all children up until 17 years living in Amsterdam in 2016. Dental costs from all Dutch healthcare insurance companies were obtained via Vektis, and socio-demographic data were obtained from Statistics Netherlands (CBS). The study population was stratified into age groups: 0-4 and 5-17 years. Dental costs were classified as no dental costs (0 euros), low dental costs (>0 to <100 euros) or high dental costs (≥100 euros). Univariable and multivariable logistic regression analyses were performed to study the distribution of dental costs and associations with socio-demographic child and parent variables. RESULTS: In the population of 142 289 children, 44 887 (31.5%) incurred no dental costs, 32 463 (22.8%) incurred low dental costs and 64 939 (45.6%) incurred high dental costs. Among children of 0-4 years, a much larger proportion (70.2%) incurred no dental costs, compared to those of 5-17 years (15.8%). In both age groups, migration background (adjusted Odds Ratio (aOR) range 1.23-1.98), low(er) household income (aOR range 0.45-0.93), low(er) parental educational level (aOR range 0.51-0.87) and living in a single-parent household (aOR range 0.89-0.91) were strongly associated with incurring high (vs. low) dental costs. Furthermore, in 5-17-year-old children, a lower level of secondary or vocational education (aOR range 1.12-1.17) and living in households receiving social benefits (aOR 1.23) were associated with incurring high dental costs. CONCLUSIONS: Among children living in Amsterdam in 2016, one in three children did not visit a dentist. For children that did visit a dentist, those with a migration background, low parental educational level and from a low household income were more likely to incur high dental costs, which could be indicative for additional restorative treatment. Hence, patterns of oral healthcare consumption, specified by type of dental care over time, and their association with oral health status, are targets for future research.

Review of long-term immunogenicity following HPV vaccination: Gaps in current knowledge.

The licensed HPV vaccines are highly efficacious and induce high levels of neutralizing antibody levels, the assumed mediators of protection. However, a correlate of protection against HPV is lacking, and the evidence is still limited as to long-term persistence of antibodies, especially following reduced dosing schedules. The World Health Organization (WHO) urges immunization of young girls as part of the strategy to eliminate cervical cancer, thus long-lasting protection is required. The current review describes long-term follow-up regarding vaccine-induced seropositivity and antibody level development following the different vaccines and dosing schedules. Implications and opportunities of long-term vaccine-induced immune responses are discussed, such as the gaps in monitoring of long-term immunogenicity, the possibilities of reduced dosing schedules, and the importance of evidence for durable immunity.

Measuring vaccine effectiveness against persistent HPV infections: a comparison of different statistical approaches.

BACKGROUND: Persistent high-risk human papillomavirus (HPV) infection is endorsed by the World Health Organization as an intermediate endpoint for evaluating HPV vaccine effectiveness/efficacy. There are different approaches to estimate the vaccine effectiveness/efficacy against persistent HPV infections. METHODS: We performed a systematic literature search in Pubmed to identify statistical approaches that have been used to estimate the vaccine effectiveness/efficacy against persistent HPV infections. We applied these methods to data of a longitudinal observational study to assess their performance and compare the obtained vaccine effectiveness (VE) estimates. RESULTS: Our literature search identified four approaches: the conditional exact test for comparing two independent Poisson rates using a binomial distribution, Generalized Estimating Equations for Poisson regression, Prentice Williams and Peterson total time (PWP-TT) and Cox proportional hazards regression. These approaches differ regarding underlying assumptions and provide different effect measures. However, they provided similar effectiveness estimates against HPV16/18 and HPV31/33/45 persistent infections in a cohort of young women eligible for routine HPV vaccination (range VE 93.7-95.1% and 60.4-67.7%, respectively) and seemed robust to violations of underlying assumptions. CONCLUSIONS: As the rate of subsequent infections increased in our observational cohort, we recommend PWP-TT as the optimal approach to estimate the vaccine effectiveness against persistent HPV infections in young women. Confirmation of our findings should be undertaken by applying these methods after longer follow-up in our study, as well as in different populations.

High Effectiveness of the Bivalent Human Papillomavirus (HPV) Vaccine Against Incident and Persistent HPV Infections up to 6 Years After Vaccination in Young Dutch Women.

Background: Monitoring vaccine effectiveness (VE) in vaccination programs is of importance for assessing the impact of immunization. This study aimed to estimate the VE of the bivalent human papillomavirus (HPV) vaccine against incident and 12-month persistent infections up to 6 years after vaccination. Methods: In 2009-2010, girls eligible for the vaccination catch-up campaign (ie, those aged 14-16 years) were enrolled into a prospective cohort. Annually, participants completed a questionnaire and submitted a self-collected vaginal swab sample for HPV testing by the SPF10-LiPA25 assay. We compared sociodemographic characteristics and infection rates between vaccinated and unvaccinated girls. The VE was adjusted for characteristics related to HPV vaccination status. We used combined end points for VE estimation. Results: In total, 1635 women, of whom 54% were fully vaccinated, were included for VE estimation. The adjusted VE against HPV16 and 18 persistent infections amounted to 97.7% (95% confidence interval [CI], 83.5%-99.7%). We found a VE against HPV31, 33, and 45 persistent infections of 61.8% (95% CI, 16.7%-82.5%). We found no indications that the protection against vaccine or cross-protective types changes over time. Conclusion: Our findings of nearly full protection against vaccine-type persistent infections and significant cross-protection to nonvaccine types in a population-based cohort study confirm the effectiveness of the bivalent HPV vaccine as estimated in trials. We found no indications for waning protection up to 6 years after vaccination.

Performance of a bedside test for tetanus immunity: results of a cross-sectional study among three EDs in the Netherlands in 2012-2013.

INTRODUCTION: Despite sustained high vaccination coverage and a national guideline by the Health Council (HC-guideline) on tetanus postexposure prophylaxis (T-PEP), tetanus sporadically occurs in the Netherlands. This study aims to assess the added value of a bedside test for tetanus immunity (Tetanos Quick Stick (TQS); Ingen BioSciences Group, France), in the context of routine T-PEP in two adult cohorts: those born before introduction of tetanus toxoid vaccination in the National Immunization Programme (NIP) in 1957 (pre-NIP-cohort; n=196) and those born after (NIP-cohort; n=405). METHODS: Adults included at the time of visiting one of three participating EDs received T-PEP as per routine recommendations. Subsequently, a nurse performed the TQS and filled in a questionnaire. We compared the indication for T-PEP based on TQS results with those based on the HC-guideline and with actually administration of T-PEP, stratified by cohort. RESULTS: Among the pre-NIP and NIP-cohort, 16% and 9%, respectively, received T-PEP, while this was not indicated based on the HC-guideline. Furthermore, 8% and 7%, respectively, did not get T-PEP, although it was indicated by the guideline. Comparing the indication derived from the HC-guideline with TQS result found that 22% (pre-NIP-cohort) and 8% (NIP-cohort) were not eligible for T-PEP according to the HC-guideline but had a negative TQS. Conversely, 36% (pre-NIP-cohort) and 73% (NIP-cohort) were eligible for T-PEP according to the HC-guideline but had positive TQS, indicating sufficient tetanus protection. CONCLUSION: Use of the TQS would allow better targeting of T-PEP. Furthermore, stricter adherence to the HC-guideline can prevent overimmunisation and decrease the risk of tetanus.

Comparing vaccines: a systematic review of the use of the non-inferiority margin in vaccine trials.

BACKGROUND: Non-inferiority (NI) randomized controlled trials (RCTs) aim to demonstrate that a new treatment is no worse than a comparator that has already shown its efficacy over placebo within a pre-specified margin. However, clear guidelines on how the NI margin should be determined are lacking for vaccine trials. A difference (seroprevalence/risk) of 10% or a geometric mean titre/concentration (GMT) ratio of 1.5 or 2.0 in antibody levels is implicitly recommended for vaccine trials. We aimed to explore which NI margins were used in vaccine RCTs and how they were determined. METHODS: A systematic search for NI vaccine RCTs yielded 177 eligible articles. Data were extracted from these articles using a standardized form and included general characteristics and characteristics specific for NI trials. Relations between the study characteristics and the NI margin used were explored. RESULTS: Among the 143 studies using an NI margin based on difference (n=136 on immunogenicity, n=2 on efficacy and n=5 on safety), 66% used a margin of 10%, 23% used margins lower than 10% (range 1-7.5%) and 11% used margins larger than 10% (range 11.5-25%). Of the 103 studies using a NI margin based on the GMT ratio, 50% used a margin of 0.67/1.5 and 49% used 0.5/2.0. As observed, 85% of the studies did not discuss the method of margin determination; and 19% of the studies lacked a confidence interval or p-value for non-inferiority. CONCLUSION: Most NI vaccine RCTs used an NI margin of 10% for difference or a GMT ratio of 1.5 or 2.0 without a clear rationale. Most articles presented enough information for the reader to make a judgement about the NI margin used and the conclusions. The reporting on the design, margins used and results of NI vaccine trials could be improved; more explicit guidelines may help to achieve this end.