A cost effectiveness analysis of repeat screening for syphilis in pregnancy as an alternative screening strategy in the UK

Syphilis is a treatable sexually transmitted infection (STI) which can be passed from mother to foetus during pregnancy resulting in congenital syphilis. Syphilis infection also increases the risk of adverse pregnancy outcomes such as stillbirth and pre-term delivery. Most cases of congenital syphilis and adverse pregnancy outcomes can be avoided if the infection is diagnosed and correctly treated during pregnancy.

In the UK, pregnant women are offered screening for syphilis, HIV and hepatitis at their first antenatal appointment, typically at or before 12 weeks gestation. Despite the very high coverage of these routine screens plus repeat screening in some higher risk women, a handful of congenital syphilis cases still occur each year, either in women who miss screening or in women who become infected with syphilis after their antenatal screen. For this reason, the UK National Screening Committee (UK NSC) commissioned Aquarius to assess the cost effectiveness of offering a repeat screen to all pregnant women later in pregnancy.

We worked closely with a small group of experts to compare the current strategy – screening in the first trimester only – with an alternative strategy – screening in the first trimester and a repeat screen later in pregnancy.  We developed a decision tree and model inputs which accounted for the sensitivity and specificity of the syphilis assay, the small number of women who do not attend antenatal care until their third trimester (thereby missing the opportunity for repeat screening) and the costs associated with screening, delivery and antenatal care for all women delivering in the UK in one year.

The model revealed that repeat screening would prevent 5.5 cases of congenital syphilis each year but at cost of £1.8 million per case avoided. When a lifetime horizon was considered, the incremental cost-effectiveness ratio (ICER) for the repeat screening strategy was £120,494 per QALY gained – well above the £20k-30k cost per QALY threshold that NICE uses to assess interventions.

The paper concludes that in the UK setting, where prevalence of syphilis is very low, repeat screening for syphilis in pregnancy would not be a cost-effective strategy and alternative strategies should be sought to prevent congenital syphilis.

This is the first published study from outside the US to compare these two screening strategies. The results will be used to inform national screening policy and are relevant countries with similar syphilis prevalence and healthcare costs. 

Huntington S, Weston G, Seedat F, et al Repeat screening for syphilis in pregnancy as an alternative screening strategy in the UK: a cost-effectiveness analysis BMJ Open 2020;10:e038505. doi: 10.1136/bmjopen-2020-038505

Modelling the choice of high-risk human papillomavirus (HR-HPV) assay in the English cervical screening programme

Aquarius developed a decision tree model to compare the use of the Aptima mRNA HR-HPV assay to a DNA HR-HPV assay in the HPV primary screening algorithm in England. Robust results from the model demonstrate that using the mRNA HR-HPV assay is cost saving and avoids unnecessary HPV recall tests, cytology tests and colposcopies compared to using a DNA HR-HPV assay.

In England, women are invited for cervical cancer screening starting at age 25 and are recalled at regular intervals until age 64. In the HPV primary screening algorithm, cervical samples are tested first for HR-HPV. Positive HPV samples are then tested using liquid based cytology to identify abnormal cells.

Aquarius developed a cost consequence analysis decision tree taking the perspective of NHS England and modelling the HPV primary screening algorithm for one simulated cohort of 2,247,439 women aged 25-64 from baseline screen through recall visits. The model endpoint was discharge to routine recall, loss-to-follow up, or referral to colposcopy. A micro-costing approach was used to estimate costs for screening in England, using published data. Head-to-head comparison of mRNA to DNA tests at baseline and with follow-up was not available for the English population. Therefore, data from the HORIZON study in Denmark with similar positivity to that in England was used.

The model indicated that using an mRNA versus DNA assay in the HPV primary screening algorithm in England can save an estimated £15.4 million and require 28,009 fewer unnecessary colposcopies, 90,605 few HR-HPV tests and 253,477 fewer cytology tests.  Uncertainty and scenario analyses demonstrate cost and resource savings will almost certainly be achieved using the mRNA assay.

PublicationWeston G, Dombrowski C, Harvey MJ, et al Use of the Aptima mRNA high-risk human papillomavirus (HR-HPV) assay compared to a DNA HR-HPV assay in the English cervical screening programme: a decision tree model based economic evaluation BMJ Open2020; 10:e031303. doi: 10.1136/bmjopen-2019-031303

Point of care testing: Disruptive innovation – is the NHS ready for it yet?

Our Managing Director, Elisabeth Adams, spoke in November about the importance of exploring the health economics of point of care testing (POCT) at the Royal Society of Medicine Telemedicine and eHealth event in London. The video of her presentation is now online – view the full talk here.

Why is it important to explore the health economics of point of care testing (POCT)?

Evaluating the health economics of POCTs can help us better understand the cost, benefits and value of implementing these tests, compared to standard laboratory tests. We need to explore the acquisition costs of innovative technology like POCTs compared to standard tests, as well as the benefits generated for patients, service providers, clinicians and public health in general. Benefits can include faster results, better care, fewer complications, more efficient services and better use of resources, and knock-on benefits like reduced prevalence of disease. Those making purchasing decisions for new tests need evidence to prove the value of the tests.

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