An economic evaluation of two cervical screening algorithms in Belgium: HR-HPV primary compared to HR-HPV and liquid-based cytology co-testing

OBJECTIVE

To assess the costs and benefits of two algorithms for cervical cancer screening in Belgium (1) high-risk human papillomavirus (HR-HPV) primary screening and (2) HR-HPV and liquid-based cytology (LBC) co-testing.

METHODS

A decision tree was adapted from published work and parameterised using HORIZON study data and Belgian cost and population data. The theoretical model represents two different screening algorithms for a cohort of 577 846 women aged 25-64 attending routine cervical screening. Scenario analyses were used to explore the impact of including vaccinated women and alternative pricing approaches. Uncertainty analyses were conducted.

RESULTS

The cost per woman screened was €113.50 for HR-HPV primary screening and €101.70 for co-testing, representing a total cost of €65 588 573 and €58 775 083, respectively, for the cohort; a 10% difference. For one screening cycle, compared to HR-HPV primary, co-testing resulted in 13 173 more colposcopies, 67 731 more HR-HPV tests and 477 020 more LBC tests. Co-testing identified 2351 more CIN2+ cases per year (27% more than HR-HPV primary) and 1602 more CIN3+ cases (24% more than HR-HPV primary) than HR-HPV primary.

CONCLUSION

In Belgium, a co-testing algorithm could increase cervical pre-cancer detection rates compared to HR-HPV primary. Co-testing would cost less than HR-HPV primary if the cost of the HPV test and LBC were cost-neutral compared to the current cost of LBC screening but would cost more if the cost per HPV test and LBC were the same in both co-testing and HR-HPV primary strategies.

Comparing the Costs and Diagnostic Outcomes of Replacing Cytology with the QIAsure DNA Methylation Test as a Triage within HPV Primary Cervical Cancer Screening in The Netherlands

Detecting hypermethylation of tumour suppressor genes could provide an alternative to liquid-based cytology (LBC) triage within HPV primary cervical screening. The impact of using the QIAsure® FAM19A4/mir124-2 DNA Methylation Test (QIAGEN, N.V, Hilden, Germany) on CIN3+ diagnoses, retention, unnecessary colposcopies, and programme costs is unknown. A decision-tree model was developed to compare LBC with the QIAsure Methylation testing to guide colposcopy referral. Incorporating clinician- and self-sampling pathways the model was informed by the Dutch cervical cancer screening programme, published studies, and manufacturer data. Clinical and cost outcomes were assessed using two scenarios for DNA methylation testing and LBC relative performance. Sensitivity analyses (deterministic and probabilistic) were performed to assess model and parameter uncertainty. A range of self-sampling uptake was assessed in scenario analyses. For the screening cohort (n = 807,269) where 22.1% self-sampled, the number of unnecessary colposcopies and CIN3+ diagnoses varied according to the relative performance of methylation testing and LBC. Irrespective of relative performance, the cost per complete screen was lower and fewer people were lost to follow-up when using DNA methylation testing. The results indicate that, within an HPV primary screening programme that incorporates self-sampling, using the QIAsure Methylation Test for triage reduces the cost per screen compared to LBC.

Estimating the Health and Economic Impact of Improved Management in Prevalent Chronic Obstructive Pulmonary Disease Populations in England, Germany, Canada, and Japan: A Modelling Study

Introduction

COPD is a leading cause of morbidity and mortality globally. Management is complex and costly. Although international quality standards for diagnosis and management exist, opportunities remain to improve outcomes, especially in reducing avoidable hospitalisations.

Objective

To estimate the potential health and economic impact of improved adherence to guideline-recommended care for prevalent, on-treatment COPD populations in four high-income settings.

Methods

A disease simulation model was developed to evaluate the impact of theoretical improvements to COPD management, comparing outcomes for usual care and policy scenarios for interventions that reduce avoidable hospitalisations: 1) increased attendance (50% vs 31-38%) of early follow-up review after severe exacerbation hospitalisation; 2) increased access (30% vs 5-10%) to an integrated disease management (IDM) programme that provides guideline adherent care.

Results

For cohorts of 100,000 patients, Policy 1 yielded additional life years (England: 523; Germany: 759; Canada: 1316; Japan: 512) and lifetime cost savings (-£2.89 million; -€6.58 million; -$40.08 million; -¥735.58 million). For Policy 2, additional life years (2299; 3619; 3656) and higher lifetime total costs (£38.15 million; €35.58 million; ¥1091.53 million) were estimated in England, Germany and Japan, and additional life years (4299) and cost savings (-$20.52 million) in Canada. Scenarios found that the cost impact depended on the modelled intervention effect size.

Conclusion

Interventions that reduce avoidable hospitalisations are estimated to improve survival and may generate cost savings. This study provides evidence on the theoretical impact of policies to improve COPD care and highlights priority areas for further research to support evidence-based policy decisions.

An economic evaluation of two PCR-based respiratory panel assays for patients admitted to hospital with community-acquired pneumonia (CAP) in the UK, France and Spain

BACKGROUND

On admission to hospital, patients with community-acquired pneumonia (CAP), undergo extensive diagnostic testing. Two high-throughput laboratory-based PCR panels which return a result in 5.5 hours (h) have been developed to test for pathogens commonly associated with upper (Respiratory 1 Panel) and lower (Respiratory 3 Panel) respiratory tract infections (GeneFirst, Oxford). These could replace multiple diagnostic tests currently used.

METHODS

An online survey, completed by senior clinicians in the UK, France and Spain, was used to collect data on the diagnostic testing of immunocompetent and immunocompromised adults admitted to hospital with CAP, including the cost of diagnostics. Data were used to inform a cost-comparison model. For each country, the average cost of diagnostic testing per patient was calculated separately for immunocompetent and immunocompromised patients. The model compared three testing strategies with standard of care (SoC). In the Panel 1 strategy, the Respiratory 1 Panel was used for patients that would otherwise have tests which could be replaced by Respiratory 1 Panel, equivalent strategies for Respiratory 3 Panel and for both panels combined were assessed.

RESULTS

In total, 48 surveys were completed (UK = 17; France = 15; Spain = 16). Compared with SoC, the Panel 1 + 3 strategy was most favourable, resulting in cost savings for immunocompetent and immunocompromised patients respectively, of €22.09 (£18.50) and €26.12 (£21.88) in the UK, €99.60 and €108.77 in France and €27.07 and €51.87 in Spain.

CONCLUSION

In all three countries, the use of these respiratory panels could reduce the average cost of diagnostics used for patients admitted to hospital with CAP.

Assessment of online self-testing and self-sampling service providers for sexually transmitted infections against national standards in the UK in 2020

OBJECTIVES

Online testing for STIs may help overcome barriers of traditional face-to-face testing, such as stigma and inconvenience. However, regulation of these online tests is lacking, and the quality of services is variable, with potential short-term and long-term personal, clinical and public health implications. This study aimed to evaluate online self-testing and self-sampling service providers in the UK against national standards.

METHODS

Providers of online STI tests (self-sampling and self-testing) in the UK were identified by an internet search of Google and Amazon (June 2020). Website information on tests and associated services was collected and further information was requested from providers via an online survey, sent twice (July 2020, April 2021). The information obtained was compared with British Association for Sexual Health and HIV and Faculty of Sexual and Reproductive Healthcare guidelines and standards for diagnostics and STI management.

RESULTS

31 providers were identified: 13 self-test, 18 self-sample and 2 laboratories that serviced multiple providers. Seven responded to the online survey. Many conflicts with national guidelines were identified, including: lack of health promotion information, lack of sexual history taking, use of tests licensed for professional-use only marketed for self-testing, inappropriate infections tested for, incorrect specimen type used and lack of advice for postdiagnosis management.

CONCLUSIONS

Very few online providers met the national STI management standards assessed, and there is concern that this will also be the case for service provision aspects that were not covered by this study. For-profit providers were the least compliant, with concerning implications for patient care and public health. Regulatory change is urgently needed to ensure that all online providers are compliant with national guidelines to ensure high-quality patient care, and providers are held to account if non-compliant.

Effectiveness of a behavioural intervention delivered by text messages (safetxt) on sexually transmitted reinfections in people aged 16-24 years: randomised controlled trial

OBJECTIVE

To quantify the effects of a series of text messages (safetxt) delivered in the community on incidence of chlamydia and gonorrhoea reinfection at one year in people aged 16-24 years.

DESIGN

Parallel group randomised controlled trial.

SETTING

92 sexual health clinics in the United Kingdom.

PARTICIPANTS

People aged 16-24 years with a diagnosis of, or treatment for, chlamydia, gonorrhoea, or non-specific urethritis in the past two weeks who owned a mobile phone.

INTERVENTIONS

3123 participants assigned to the safetxt intervention received a series of text messages to improve sex behaviours: four texts daily for days 1-3, one or two daily for days 4-28, two or three weekly for month 2, and 2-5 monthly for months 3-12. 3125 control participants received a monthly text message for one year asking for any change to postal or email address. It was hypothesised that safetxt would reduce the risk of chlamydia and gonorrhoea reinfection at one year by improving three key safer sex behaviours: partner notification at one month, condom use, and sexually transmitted infection testing before unprotected sex with a new partner. Care providers and outcome assessors were blind to allocation.

MAIN OUTCOME MEASURES

The primary outcome was the cumulative incidence of chlamydia or gonorrhoea reinfection at one year, assessed by nucleic acid amplification tests. Safety outcomes were self-reported road traffic incidents and partner violence. All analyses were by intention to treat.

RESULTS

6248 of 20 476 people assessed for eligibility between 1 April 2016 and 23 November 2018 were randomised. Primary outcome data were available for 4675/6248 (74.8%). At one year, the cumulative incidence of chlamydia or gonorrhoea reinfection was 22.2% (693/3123) in the safetxt arm versus 20.3% (633/3125) in the control arm (odds ratio 1.13, 95% confidence interval 0.98 to 1.31). The number needed to harm was 64 (95% confidence interval number needed to benefit 334 to ∞ to number needed to harm 24) The risk of road traffic incidents and partner violence was similar between the groups.

CONCLUSIONS

The safetxt intervention did not reduce chlamydia and gonorrhoea reinfections at one year in people aged 16-24 years. More reinfections occurred in the safetxt group. The results highlight the need for rigorous evaluation of health communication interventions.

TRIAL REGISTRATION

ISRCTN registry ISRCTN64390461.

Modelling the Effect of COVID-19 Mass Vaccination on Acute Hospital Admissions

BACKGROUND

Managing high levels of acute COVID-19 bed occupancy can affect the quality of care provided to both affected patients and those requiring other hospital services. Mass vaccination has offered a route to reduce societal restrictions while protecting hospitals from being overwhelmed. Yet, early in the mass vaccination effort, the possible impact on future bed pressures remained subject to considerable uncertainty. The aim of this study was to model the effect of vaccination on projections of acute and intensive care bed demand within a one million resident healthcare system located in South West England.

METHODS

An age-structured epidemiological model of the Susceptible-Exposed-Infectious-Recovered (SEIR) type was fitted to local data up to the time of the study, in early March 2021. Model parameters and vaccination scenarios were calibrated through a system-wide multi-disciplinary working group, comprising public health intelligence specialists, healthcare planners, epidemiologists, and academics. Scenarios assumed incremental relaxations to societal restrictions according to the envisaged UK Government timeline, with all restrictions to be removed by 21 June 2021.

RESULTS

Achieving 95% vaccine uptake in adults by 31 July 2021 would not avert a third wave in autumn 2021 but would produce a median peak bed requirement approximately 6% (IQR: 1% to 24%) of that experienced during the second wave (January 2021). A two-month delay in vaccine rollout would lead to significantly higher peak bed occupancy, at 66% (11% to 146%) of that of the second wave. If only 75% uptake was achieved (the amount typically associated with vaccination campaigns) then the second wave peak for acute and intensive care beds would be exceeded by 4% and 19% respectively, an amount which would seriously pressure hospital capacity.

CONCLUSION

Modelling influenced decision making among senior managers in setting COVID-19 bed capacity levels, as well as highlighting the importance of public health in promoting high vaccine uptake among the population. Forecast accuracy has since been supported by actual data collected following the analysis, with observed peak bed occupancy falling comfortably within the inter-quartile range of modelled projections.

Preferences for chlamydia testing and management in Hong Kong: a discrete choice experiment

OBJECTIVES

As most chlamydia cases are asymptomatic, regular testing and timely management may be necessary for control. We aimed to determine the preferences of people living in Hong Kong for chlamydia testing and management services.

METHODS

An online panel of sexually active individuals living in Hong Kong completed the survey with two discrete choice experiments (DCEs). The first DCE examined the preferred attributes of a chlamydia testing service (cost, location, appointment time, speed of results, delivery of results and availability of other STI testing). The second DCE examined the preferred attributes of a chlamydia management service (cost, access to patient-delivered partner therapy, location, travel time, type of person consulted and attitude of staff).

RESULTS

In total, 520 individuals participated: average age 36.8 years (SD 9.9), 40% males and 66% had a bachelor's degree or higher. Choosing to test was most influenced by cost, followed by speed of results, delivery of results, extra STI testing, appointment available and the least important was the location of testing. Choosing to attend for management was most influenced by staff's attitude, followed by cost, who they consult, access to patient-delivered partner therapy, travel time and the least important was treatment location.

CONCLUSION

To design effective chlamydia testing and management services, it is vital to respond to patient needs and preferences. For people living in Hong Kong, cost and staff attitude were the most important factors for deciding whether to test or be managed for chlamydia, respectively.

Serological Evidence of Human Infection with Coxiella burnetii after Occupational Exposure to Aborting Cattle

Cattle are broadly deemed a source of Coxiella burnetii; however, evidence reinforcing their role in human infection is scarce. Most published human Q fever outbreaks relate to exposure to small ruminants, notably goats. Anti-phase II C. burnetii IgG and IgM were measured by indirect fluorescent antibody tests in 27 farm and veterinary diagnostic laboratory workers to ascertain whether occupational exposure to cattle aborting due to C. burnetii was the probable source of exposure. Four serological profiles were identified on the basis of anti-phase II IgG and IgM titres. Profile 1, characterised by high IgM levels and concurrent, lower IgG titres (3/27; 11.1%); Profile 2, with both isotypes with IgG titres higher than IgM (2/27; 7.4%); Profile 3 with only IgG phase II (5/27; 18.5%); and Profile 4, in which neither IgM nor IgG were detected (17/27; 63.0%). Profiles 1 and 2 are suggestive of recent C. burnetii exposure, most likely 2.5-4.5 months before testing and, hence, during the window of exposure to the bovine abortions. Profile 3 suggested C. burnetii exposure that most likely predated the window of exposure to aborting cattle, while Profile 4 represented seronegative individuals and, hence, likely uninfected. This study formally linked human Q fever to exposure to C. burnetii infected cattle as a specific occupational hazard for farm and laboratory workers handling bovine aborted material.

Evidence of changing sexual behaviours and clinical attendance patterns, alongside increasing diagnoses of STIs in MSM and TPSM

Background

Due to rising numbers of STI diagnosis and increasing prevalence of antimicrobial resistance, we explored trends in STI testing frequency and diagnoses, alongside sexual decision making and attitudes concerning condom use and HIV pre-exposure prophylaxis (PrEP) at a large urban UK sexual health clinic.

Methods

We examined 66 528 electronic patient records covering 40 321 attendees between 2016 and 2019, 3977 of whom were men who have sex with men or trans persons who have sex with men (MSM/TPSM). We also explored responses from MSM/TPSM attendees sent an electronic questionnaire between November 2018 and 2019 (n=1975) examining behaviours/attitudes towards PrEP. We measured trends in STI diagnoses and sexual behaviours including condomless anal intercourse (CAI), using linear and logistic regression analyses.

Results

Tests resulting in gonorrhoea, chlamydia or syphilis diagnoses increased among MSM/TPSM from 13.5% to 18.5% between 2016 and 2019 (p<0.001). The average MSM/TPSM STI testing frequency increased from 1.5/person/year to 2.1/person/year (p=0.017). Gay MSM/TPSM had the highest proportions of attendances resulting in diagnoses, increasing from 15.1% to 19.6% between 2016 and 2019 (p<0.001) compared with bisexual/other MSM/TPSM increasing from 6.9% to 14.5% (p<0.001), alongside smaller but significant increases in non-MSM/TPSM from 5.9% to 7.7% (p<0.001).

The proportion of MSM/TPSM clinic attendees reporting CAI in the previous 3 months prior to at least one appointment in a given year increased significantly from 40.6% to 45.5% between 2016 and 2019 (p<0.0001) and average number of partners from 3.8 to 4.5 (p=0.002). Of 617 eligible questionnaire responses, 339/578 (58.7%) HIV-negative and 29/39 (74.4%) HIV-positive MSM/TPSM indicated they would be more likely to have CAI with someone on PrEP versus not on PrEP. 358/578 (61.9%) HIV-negative respondents said that PrEP use would make them more likely to have CAI with HIV-negative partners.

Conclusion

Rising numbers of STI diagnoses among MSM/TPSM are not attributable to increased testing alone. Increased CAI and number of partners may be attributable to evolving sexual decision making among PrEP users and their partners. Proportionally, bisexual/other MSM/TPSM have the steepest increase in STI diagnoses.

A hitchhiker guide to manta rays: Patterns of association between Mobula alfredi, M. birostris, their symbionts, and other fishes in the Maldives

Despite being among the largest and most charismatic species in the marine environment, considerable gaps remain in our understanding of the behavioural ecology of manta rays (Mobula alfredi, M. birostris). Manta rays are often sighted in association with an array of smaller hitchhiker fish species, which utilise their hosts as a sanctuary for shelter, protection, and the sustenance they provide. Species interactions, rather than the species at the individual level, determine the ecological processes that drive community dynamics, support biodiversity and ecosystem health. Thus, understanding the associations within marine communities is critical to implementing effective conservation and management. However, the underlying patterns between manta rays, their symbionts, and other hitchhiker species remain elusive. Here, we explore the spatial and temporal variation in hitchhiker presence with M. alfredi and M. birostris throughout the Maldives and investigate the factors which may influence association using generalised linear mixed effects models (GLMM). For the first time, associations between M. alfredi and M. birostris with hitchhiker species other than those belonging to the family Echeneidae are described. A variation in the species of hitchhiker associated with M. alfredi and M. birostris was identified, with sharksucker remora (Echeneis naucrates) and giant remora (Remora remora) being the most common, respectively. Spatiotemporal variation in the presence of manta rays was identified as a driver for the occurrence of ephemeral hitchhiker associations. Near-term pregnant female M. alfredi, and M. alfredi at cleaning stations, had the highest likelihood of an association with adult E. naucrates. Juvenile E. naucrates were more likely to be associated with juvenile M. alfredi, and a seasonal trend in E. naucrates host association was identified. Remora were most likely to be present with female M. birostris, and a mean number of 1.5 ± 0.5 R. remora were observed per M. birostris. It is hoped these initial findings will serve as the basis for future work into the complex relationships between manta rays and their hitchhikers.

Developing a model to predict individualised treatment for gonorrhoea: a modelling study

OBJECTIVE

To develop a tool predicting individualised treatment for gonorrhoea, enabling treatment with previously recommended antibiotics, to reduce use of last-line treatment ceftriaxone.

DESIGN

A modelling study.

SETTING

England and Wales.

PARTICIPANTS

Individuals accessing sentinel health services.

INTERVENTION

Developing an Excel model which uses participants' demographic, behavioural and clinical characteristics to predict susceptibility to legacy antibiotics. Model parameters were calculated using data for 2015-2017 from the Gonococcal Resistance to Antimicrobials Surveillance Programme.

MAIN OUTCOME MEASURES

Estimated number of doses of ceftriaxone saved, and number of people delayed effective treatment, by model use in clinical practice. Model outputs are the predicted risk of resistance to ciprofloxacin, azithromycin, penicillin and cefixime, in groups of individuals with different combinations of characteristics (gender, sexual orientation, number of recent sexual partners, age, ethnicity), and a treatment recommendation.

RESULTS

Between 2015 and 2017, 8013 isolates were collected: 64% from men who have sex with men, 18% from heterosexual men and 18% from women. Across participant subgroups, stratified by all predictors, resistance prevalence was high for ciprofloxacin (range: 11%-51%) and penicillin (range: 6%-33%). Resistance prevalence for azithromycin and cefixime ranged from 0% to 13% and for ceftriaxone it was 0%. Simulating model use, 88% of individuals could be given cefixime and 10% azithromycin, saving 97% of ceftriaxone doses, with 1% of individuals delayed effective treatment.

CONCLUSIONS

Using demographic and behavioural characteristics, we could not reliably identify a participant subset in which ciprofloxacin or penicillin would be effective. Cefixime resistance was almost universally low; however, substituting ceftriaxone for near-uniform treatment with cefixime risks re-emergence of resistance to cefixime and ceftriaxone. Several subgroups had low azithromycin resistance, but widespread azithromycin monotherapy risks resistance at population level. However, this dataset had limitations; further exploration of individual characteristics to predict resistance to a wider range of legacy antibiotics may still be appropriate.

Molecular prevalence of Coxiella burnetii in bulk-tank milk from bovine dairy herds: Systematic review and meta-analysis

Coxiella burnetii is an obligate intracellular zoonotic bacterium that causes Q fever. Ruminants, including cattle, are broadly known to be reservoirs for this bacterium. Since 2006, many research groups have evaluated the herd-level prevalence of C. burnetii in cattle by molecular techniques on composite milk samples. This study explored the global C. burnetii herd-level prevalence from studies done on bovine bulk-tank milk (BTM) samples using PCR-based analysis. Also, moderators were investigated to identify sources of heterogeneity. Databases (CAB Abstracts, Medline via Ovid, PubMed, Web of Science and Google Scholar) were searched for index articles on C. burnetii prevalence in BTM samples by PCR published between January-1973 and November-2018. Numerous studies (1054) were initially identified, from which seventeen original publications were included in the meta-analysis based on the pre-defined selection criteria. These studies comprised 4031 BTM samples from twelve countries. A random-effects model was used because of considerable heterogeneity (I² = 98%) to estimate the herd-level prevalence of C. burnetii as 37.0%(CI_95%25.2–49.5%). The average herd size appeared to account for a high level of the heterogeneity. No other moderators (geographic location, gross national income or notification criteria for Q fever) seemed to be determinant. This systematic evaluation demonstrated a high molecular prevalence of C. burnetii in BTM samples both in European and non-European countries, evidencing a widespread herd-level circulation of this agent in bovine dairy farms around the world. Meta-regression showed herd size as the most relevant moderator with the odds of a BTM sample testing positive doubling with every unit increase.

•

First meta-analysis of the PCR-based prevalence of C. burnetii in bovine milk

•

Results showed a high molecular prevalence of C. burnetii in bulk-tank milk samples.

•

C. burnetii is widely distributed in dairy farms in Europe and the wider world.

•

Current results reinforce the need for further investigations on this zoonosis.

Safetxt: a safer sex intervention delivered by mobile phone messaging on sexually transmitted infections (STI) among young people in the UK - protocol for a randomised controlled trial

INTRODUCTION

Young people aged 16 to 24 have the highest prevalence of genital chlamydia and gonorrhoea compared with other age groups and re-infection rates following treatment are high. Long-term adverse health effects include subfertility and ectopic pregnancy, particularly among those with repeated infections. We developed the safetxt intervention delivered by text message to reduce sexually transmitted infection (STI) by increasing partner notification, condom use and (STI) testing among young people in the UK.

METHODS AND ANALYSIS

A single-blind randomised trial to reliably establish the effect of the safetxt intervention on chlamydia and gonorrhoea infection at 1 year. We will recruit 6250 people aged 16 to 24 years who have recently been diagnosed with chlamydia, gonorrhoea or non-specific urethritis from health services in the UK. Participants will be allocated to receive the safetxt intervention (text messages designed to promote safer sexual health behaviours) or to receive the control text messages (monthly messages asking participants about changes in contact details) by an automated remote online randomisation system. The primary outcome will be the cumulative incidence of chlamydia and gonorrhoea infection at 1 year assessed by nucleic acid amplification tests. Secondary outcomes include partner notification, correct treatment of infection, condom use and STI testing prior to sex with new partners.

ETHICS AND DISSEMINATION

Ethics approval was obtained from NHS Health Research Authority - London - Riverside Research Ethics Committee (REC reference: 15/LO/1665) and the London School of Hygiene & Tropical Medicine. We will submit the results of the trial for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

International Standard Randomised Controlled Trials Number: ISRCTN64390461. Registered on 17^th March 2016. WHO trial registration data set available at: http://apps.who.int/trialsearch/Trial2.aspx?TrialID=ISRCTN64390461.

TRIAL PROTOCOL VERSION

12, 19^th July 2018.

Agent-based modelling study of antimicrobial-resistant Neisseria gonorrhoeae transmission in men who have sex with men: towards individualised diagnosis and treatment

Background Antimicrobial-resistant (AMR) gonorrhoea is a global public health threat. Discriminatory point-of-care tests (POCT) to detect drug sensitivity are under development, enabling individualised resistance-guided therapy.

METHODS

An individual-based dynamic transmission model of gonorrhoea infection in MSM living in London has been developed, incorporating ciprofloxacin-sensitive and resistant strains. The time-dependent sexual contact network is captured by periodically restructuring active connections to reflect the transience of contacts. Different strategies to improve treatment selection were explored, including discriminatory POCT and selecting partner treatment based on either the index case or partner susceptibility. Outcomes included population prevalence of gonorrhoea and drug dose counts.

RESULTS

It is shown that using POCT to detect ciprofloxacin-sensitive infections could result in a large decrease in ceftriaxone doses (by 70% compared with the reference case in the simulations of this study). It also suggests that ceftriaxone use can be reduced with existing technologies, albeit to a lesser degree; either using index case sensitivity profiles to direct treatment of partners, or testing notified partners with strain discriminatory laboratory tests before treatment, reduced ceftriaxone use in our model (by 27% and 47% respectively).

CONCLUSIONS

POCT to detect ciprofloxacin-sensitive gonorrhoea are likely to dramatically reduce reliance on ceftriaxone, but requires the implementation of new technology. In the meantime, the proportion of unnecessary ceftriaxone treatment by testing partners before treatment could be reduced significantly. Alternatively, index case sensitivity profiles could be used to select effective treatments for partners.

Online testing for sexually transmitted infections: A whole systems approach to predicting value

BACKGROUND

Online testing for sexually transmitted infections has a lower unit cost than testing in clinical services and economic analysis has focused on the cost per test and cost per diagnosis in clinics and online. However, online services generate new demand for testing and shift activity between services, requiring system-level analysis to effectively predict cost-effectiveness.

METHODS AND FINDINGS

Routinely collected, anonymised, retrospective data on sexual health service activity from all specialist services (clinic and online) within an inner London sexual health economy were collated and harmonised to generate a complete dataset of individual level clinic attendances. Clinic activity and diagnoses were coded using nationally standardised codes assigned by clinicians. Costs were taken from locally or regionally agreed sexual health tariffs. The introduction of online services changed patterns of testing. In an inner London sexual health economy, online STI testing increased total number of tests, the total cost of testing and total diagnoses while slightly reducing the average cost per diagnosis. Two years after the introduction of online services 37% of tests in the were provided online and total diagnoses increased. The positivity of online services is generally lower than that in clinics but varies between contexts. Where the positivity ratio between clinic and online is less than the cost ratio, online services will reduce cost per diagnosis. In this analysis, areas with different classifications as urban and rural had different clinic/online positivity ratios changing the cost effectiveness between areas. Even after the introduction of online services, simple STI testing activity continues in clinics and providers should consider online-first options where clinically appropriate.

CONCLUSIONS

Online services for STI testing are not 'stand alone'. They change STI testing behaviour with impacts on all elements of the sexual health economy. Planning, development and monitoring of such services should reference the dynamic nature of these systems and the role of online services within them.

Spatial Patterns of Primate Electrocutions in Diani, Kenya

Electrocution from power infrastructure threatens many primate species, yet knowledge of effective evidence-based mitigation strategies is limited. Mitigation planning requires an understanding of the spatial distribution of electrocutions to prioritize high-risk areas. In Diani, a coastal Kenyan town, electrocution is an important cause of death for five primate species. In this study we aim to describe the spatial patterns of electrocutions and electric shock incidents (collectively referred to as electrocutions hereafter) and identify electrocution hotspots to guide an effective primate conservation approach in Diani. Colobus Conservation, a not-for-profit organization, has recorded electrocutions and annual primate census data since 1998. We georeferenced 329 electrocution data points and analyzed them using QGIS. We identified and compared hotspots across species, seasons, and time using kernel density estimation and Getis-Ord-Gi*. We employed spatial regression models to test whether primate population density and power line density predicted the location of electrocution hotspots. Electrocutions occurred in hotspots that showed little variation in location between species and seasons. The limited variation in hotspot location over time likely occurred as a result of new building development in Diani and variability in primate detection rates by community members. Primate density and power line density were significant predictors of electrocution density for Angolan black-and-white colobus (Colobus angolensis palliatus) and Sykes monkeys (Cercopithecus mitis albogularis), but the relationship was weak, suggesting the presence of additional risk factors. This study provides a framework for systematic spatial prioritization of power lines that can be used to reduce primate electrocutions in Diani, and can be adopted in other areas of the world where primates are at risk from electrocution.

Comparing the characteristics of users of an online service for STI self-sampling with clinic service users: a cross-sectional analysis

Objectives

Online services for self-sampling at home could improve access to STI testing; however, little is known about those using this new modality of care. This study describes the characteristics of users of online services and compares them with users of clinic services.

Methods

We conducted a cross-sectional analysis of routinely collected data on STI testing activity from online and clinic sexual health services in Lambeth and Southwark between 1January 2016 and 31March 2016. Activity was included for chlamydia, gonorrhoea, HIV and syphilis testing for residents of the boroughs aged 16 years and older. Logistic regression models were used to explore potential associations between type of service use with age group, gender, ethnic group, sexual orientation, positivity and Index of Multiple Deprivation (IMD) quintiles. We used the same methods to explore potential associations between return of complete samples for testing with age group, gender, ethnic group, sexual orientation and IMD quintiles among online users.

Results

6456 STI tests were carried out by residents in the boroughs. Of these, 3582 (55.5%) were performed using clinic services and 2874 (44.5%) using the online service. In multivariate analysis, online users were more likely than clinic users to be aged between 20 and 30 years, female, white British, homosexual or bisexual, test negative for chlamydia or gonorrhoea and live in less deprived areas. Of the individuals that ordered a kit from the online service, 72.5% returned sufficient samples. In multivariate analysis, returners were more likely than non-returners to be aged >20 years and white British.

Conclusion

Nearly half (44.5%) of all basic STI testing was done online, although the characteristics of users of clinic and online services differed and positivity rates for those using the online service for testing were lower. Clinics remain an important point of access for some groups.

Pelvic inflammatory disease risk following negative results from chlamydia nucleic acid amplification tests (NAATs) versus non-NAATs in Denmark: A retrospective cohort

BACKGROUND

Nucleic Acid Amplification Tests (NAATs) are the recommended test type for diagnosing Chlamydia trachomatis (chlamydia). However, less sensitive diagnostic methods-including direct immunofluorescence (IF) and enzyme-linked immunoassay (ELISA)-remain in use in lower resourced settings. We estimate the risk of pelvic inflammatory disease (PID) following undiagnosed infection in women tested with non-NAATs and estimate the health gain from using accurate diagnostic tests.

METHODS AND FINDINGS

We used Denmark's national Chlamydia Study dataset to extract all chlamydia tests performed in women aged 15-34 years (1998-2001). Tests were categorised as non-NAAT (IF/ELISA) or NAAT and limited to each woman's first test in the study period. We linked test data to hospital presentations for PID within 12 months from the Danish National Patient Register. The study included 272,105 women with a chlamydia test, just under half (44.78%, n = 121,857) were tested using NAATs. Overall, 6.38% (n = 17,353) tested positive for chlamydia and 0.64% (n = 1,732) were diagnosed with PID within 12 months. The risk of PID following a positive chlamydia test did not differ by test type (NAAT 0.81% [95% CI 0.61-1.00], non-NAAT 0.78% [0.59-0.96]). The risk of PID following a negative test was significantly lower in women tested with NAATs compared to non-NAATs (0.55% [0.51-0.59] compared to 0.69% [0.64-0.73]; adjusted odds ratio (AOR) 0.83 [0.75-0.93]). We estimate that 18% of chlamydia infections in women tested with a non-NAAT were undiagnosed and that the risk of progression from undiagnosed chlamydia infection to PID within 12 months was 9.52% (9.30-9.68). Using non-NAATs could lead to an excess 120 cases of PID per 100,000 women tested compared to using NAATs. The key limitations of this study are under ascertainment of PID cases, misclassification bias in chlamydia and PID exposure status, bias to the association between clinical presentation and test type and the presence of unmeasured confounders (including other sexually transmitted infection [STI] diagnoses and clinical indication for chlamydia test).

CONCLUSION

This retrospective observational study estimates the positive impact on women's reproductive health from using accurate chlamydia diagnostic tests and provides further evidence for restricting the use of inferior tests. Women with a negative chlamydia test have a 17% higher adjusted risk of PID by 12 months if they are tested using a non-NAAT compared to a NAAT.

Cross-sectional study to evaluate Trichomonas vaginalis positivity in women tested for Neisseria gonorrhoeae and Chlamydia trachomatis, attending genitourinary medicine and primary care clinics in Bristol, South West England

BACKGROUND

Highly sensitive, commercial nucleic acid amplification tests (NAAT) for Trichomonas vaginalis have only recently been recommended for use in the UK. While testing for T. vaginalis is routine in symptomatic women attending genitourinary medicine (GUM) clinics, it is rare in asymptomatic women or those attending primary care. The aim of this study was to evaluate the positivity of T. vaginalis using a commercial NAAT, in symptomatic and asymptomatic women undergoing testing for chlamydia and gonorrhoea in GUM and primary care settings.

METHODS

Samples from 9186 women undergoing chlamydia and gonorrhoea testing in South West England between May 2013 and Jan 2015 were also tested for T. vaginalis by NAAT alongside existing tests.

RESULTS

T. vaginalis positivity using NAAT was as follows: in GUM 4.5% (24/530, symptomatic) and 1.7% (27/1584, asymptomatic); in primary care 2.7% (94/3499, symptomatic) and 1.2% (41/3573, asymptomatic). Multivariable regression found that in GUM older age, black ethnicity and deprivation were independent risk factors for T. vaginalis infection. Older age and deprivation were also risk factors in primary care. Testing women presenting with symptoms in GUM and primary care using TV NAATs is estimated to cost £260 per positive case diagnosed compared with £716 using current microbiological tests.

CONCLUSIONS

Aptima TV outperforms existing testing methods used to identify T. vaginalis infection in this population. An NAAT should be used when testing for T. vaginalis in women who present for testing with symptoms in primary care and GUM, based on test performance and cost.

Comparison of the population excess fraction of Chlamydia trachomatis infection on pelvic inflammatory disease at 12-months in the presence and absence of chlamydia testing and treatment: Systematic review and retrospective cohort analysis

BACKGROUND

The impact of Chlamydia trachomatis (chlamydia) control on the incidence of pelvic inflammatory disease (PID) is theoretically limited by the proportion of PID caused by chlamydia. We estimate the population excess fraction (PEF) of treated chlamydia infection on PID at 12-months in settings with widespread chlamydia control (testing and treatment) and compare this to the estimated PEF of untreated chlamydia.

METHODS

We used two large retrospective population-based cohorts of women of reproductive age from settings with widespread chlamydia control to calculate the PEF of treated chlamydia on PID at 12-months. We undertook a systematic review to identify further studies that reported the risk of PID in women who were tested for chlamydia (infected and uninfected). We used the same method to calculate the PEF in eligible studies then compared all estimates of PEF.

RESULTS

The systematic review identified a single study, a randomised controlled trial of chlamydia screening (POPI-RCT). In the presence of testing and treatment <10% of PID at 12-months was attributable to treated (baseline) chlamydia infections (Manitoba: 8.86%(95%CI 7.15-10.75); Denmark: 3.84%(3.26-4.45); screened-arm POPI-RCT: 0.99%(0.00-29.06)). In the absence of active chlamydia treatment 26.44%(11.57-46.32) of PID at 12-months was attributable to untreated (baseline) chlamydia infections (deferred-arm POPI-RCT). The PEFs suggest that eradicating baseline chlamydia infections could prevent 484 cases of PID at 12-months per 100,000 women in the untreated setting and 13-184 cases of PID per 100,000 tested women in the presence of testing and treatment.

CONCLUSION

Testing and treating chlamydia reduced the PEF of chlamydia on PID by 65% compared to the untreated setting. But in the presence of testing and treatment over 90% of PID could not be attributed to a baseline chlamydia infection. More information is needed about the aetiology of PID to develop effective strategies for improving the reproductive health of women.

Risk of reproductive complications following chlamydia testing: a population-based retrospective cohort study in Denmark

BACKGROUND

Uncertainty in the risk of reproductive complications (pelvic inflammatory disease, ectopic pregnancy, and tubal factor infertility) following chlamydia infection and repeat infection hampers the design of evidence-based chlamydia control programmes. We estimate the association between diagnosed chlamydia and episodes of hospital health care (inpatient, outpatient, and emergency department) for a reproductive complication.

METHODS

We constructed and analysed a retrospective population-based cohort of women aged 15-44 years from administrative records in Denmark (1995-2012). We used a subset of the national Danish Chlamydia Study. The master dataset contains all residents of Denmark (including Greenland) who had a positive chlamydia test recorded by a public health microbiology laboratory from Jan 1, 1992, to Nov 2, 2011. Individuals were randomly matched (by age and sex) to four individuals drawn from the population register (Danish Civil Registration System) who did not have a positive chlamydia test during this interval. The outcomes in the study were hospital episodes of health-care (inpatient, outpatient, and emergency department) with a diagnosis of pelvic inflammatory disease, ectopic pregnancy, or tubal factor infertility.

FINDINGS

The 516 720 women (103 344 positive, 182 879 negative, 230 497 never-tested) had a mean follow-up of 7·96 years. Compared with women with only negative tests, the risk of each complication was 30% higher in women with one or more positive tests (pelvic inflammatory disease, adjusted hazard ratio [AHR] 1·50 [95% CI 1·43-1·57]; ectopic pregnancy, AHR 1·31 [1·25-1·38]; tubal factor infertility, AHR 1·37 [1·24-1·52]) and 60% lower in women who were never-tested (pelvic inflammatory disease, AHR 0·33 [0·31-0·35]; ectopic pregnancy, AHR 0·42 [0·39-0·44]; tubal factor infertility AHR 0·29 [0·25-0·33]). A positive test had a minor absolute impact on health as the difference in the lifetime incidence of complications was small between women who tested positive and those who tested negative (pelvic inflammatory disease, 0·6%; ectopic pregnancy, 0·2%; tubal factor infertility, 0·1%). Repeat infections increased the risk of pelvic inflammatory disease by a further 20% (AHR 1·20, 95% CI 1·11-1·31).

INTERPRETATION

A single diagnosed chlamydia infection increased the risk of all complications and a repeat diagnosed infection further increased the risk of pelvic inflammatory disease. Therefore, control programmes must prevent first and repeat infections to improve women's reproductive health.

FUNDING

Unrestricted partial funding from Frederiksberg Kommune, Frederiksberg, Denmark. BD held an Medical Research Council Population Health Scientist Fellowship (G0902120). KT held an National Institute for Health Research Post-Doctoral Fellowship 2009-02-055.

Heterogeneity in risk of pelvic inflammatory diseases after chlamydia infection: a population-based study in Manitoba, Canada

BACKGROUND

The association between chlamydia infection and pelvic inflammatory disease (PID) is a key parameter for models evaluating the impact of chlamydia control programs. We quantified this association using a retrospective population-based cohort.

METHODS

We used administrative health data sets to construct a retrospective population-based cohort of women and girls aged 12-24 years who were resident in Manitoba, Canada, between 1992 and 1996. We performed survival analysis on a subcohort of individuals who were tested for chlamydia to estimate the risk of PID diagnosed in a primary care, outpatient, or inpatient setting after ≥ 1 positive chlamydia test.

RESULTS

A total of 73 883 individuals contributed 625 621 person years of follow-up. Those with a diagnosis of chlamydia had an increased risk of PID over their reproductive lifetime compared with those who tested negative (adjusted hazard ratio [AHR], 1.55; 95% confidence interval [CI], 1.43-1.70). This risk increased with each subsequent infection: the AHR was 1.17 for first reinfection (95% CI, 1.06-1.30) and 1.35 for the second (95% CI, 1.04-1.75). The increased risk of PID from reinfection was highest in younger individuals (AHR, 4.55 (95% CI, 3.59-5.78) in individuals aged 12-15 years at the time of their second reinfection, compared with individuals older than 30 years).

CONCLUSIONS

There is heterogeneity in the risk of PID after a chlamydia infection. Describing the progression to PID in mathematical models as an average rate may be an oversimplification; more accurate estimates of the cost-effectiveness of screening may be obtained by using an individual-based measure of risk. Health inequalities may be reduced by targeting health promotion interventions at sexually active girls younger than 16 years and those with a history of chlamydia.

How robust are the natural history parameters used in chlamydia transmission dynamic models? A systematic review

Transmission dynamic models linked to economic analyses often form part of the decision making process when introducing new chlamydia screening interventions. Outputs from these transmission dynamic models can vary depending on the values of the parameters used to describe the infection. Therefore these values can have an important influence on policy and resource allocation. The risk of progression from infection to pelvic inflammatory disease has been extensively studied but the parameters which govern the transmission dynamics are frequently neglected. We conducted a systematic review of transmission dynamic models linked to economic analyses of chlamydia screening interventions to critically assess the source and variability of the proportion of infections that are asymptomatic, the duration of infection and the transmission probability. We identified nine relevant studies in Pubmed, Embase and the Cochrane database. We found that there is a wide variation in their natural history parameters, including an absolute difference in the proportion of asymptomatic infections of 25% in women and 75% in men, a six-fold difference in the duration of asymptomatic infection and a four-fold difference in the per act transmission probability. We consider that much of this variation can be explained by a lack of consensus in the literature. We found that a significant proportion of parameter values were referenced back to the early chlamydia literature, before the introduction of nucleic acid modes of diagnosis and the widespread testing of asymptomatic individuals. In conclusion, authors should use high quality contemporary evidence to inform their parameter values, clearly document their assumptions and make appropriate use of sensitivity analysis. This will help to make models more transparent and increase their utility to policy makers.

The impact of needle and syringe provision and opiate substitution therapy on the incidence of hepatitis C virus in injecting drug users: pooling of UK evidence

AIMS

To investigate whether opiate substitution therapy (OST) and needle and syringe programmes (NSP) can reduce hepatitis C virus (HCV) transmission among injecting drug users (IDUs).

DESIGN

Meta-analysis and pooled analysis, with logistic regression allowing adjustment for gender, injecting duration, crack injecting and homelessness.

SETTING

Six UK sites (Birmingham, Bristol, Glasgow, Leeds, London and Wales), community recruitment.

PARTICIPANTS

A total of 2986 IDUs surveyed during 2001-09.

MEASUREMENT

Questionnaire responses were used to define intervention categories for OST (on OST or not) and high NSP coverage (≥100% versus <100% needles per injection). The primary outcome was new HCV infection, measured as antibody seroconversion at follow-up or HCV antibody-negative/RNA-positive result in cross-sectional surveys.

FINDINGS

Preliminary meta-analysis showed little evidence of heterogeneity between the studies on the effects of OST (I2=48%, P=0.09) and NSP (I2=0%, P=0.75), allowing data pooling. The analysis of both interventions included 919 subjects with 40 new HCV infections. Both receiving OST and high NSP coverage were associated with a reduction in new HCV infection [adjusted odds ratios (AORs)=0.41, 95% confidence interval (CI): 0.21-0.82 and 0.48, 95% CI: 0.25-0.93, respectively]. Full harm reduction (on OST plus high NSP coverage) reduced the odds of new HCV infection by nearly 80% (AOR=0.21, 95% CI: 0.08-0.52). Full harm reduction was associated with a reduction in self-reported needle sharing by 48% (AOR 0.52, 95% CI: 0.32-0.83) and mean injecting frequency by 20.8 injections per month (95% CI: -27.3 to -14.4).

CONCLUSIONS

There is good evidence that uptake of opiate substitution therapy and high coverage of needle and syringe programmes can substantially reduce the risk of hepatitis C virus transmission among injecting drug users. Research is now required on whether the scaling-up of intervention exposure can reduce and limit hepatitis C virus prevalence in this population.

Predicting the population impact of chlamydia screening programmes: comparative mathematical modelling study

BACKGROUND

Published individual-based, dynamic sexual network modelling studies reach different conclusions about the population impact of screening for Chlamydia trachomatis. The objective of this study was to conduct a direct comparison of the effect of organised chlamydia screening in different models.

METHODS

Three models simulating population-level sexual behaviour, chlamydia transmission, screening and partner notification were used. Parameters describing a hypothetical annual opportunistic screening program in 16-24 year olds were standardised, whereas other parameters from the three original studies were retained. Model predictions of the change in chlamydia prevalence were compared under a range of scenarios.

RESULTS

Initial overall chlamydia prevalence rates were similar in women but not men and there were age and sex-specific differences between models. The number of screening tests carried out was comparable in all models but there were large differences in the predicted impact of screening. After 10 years of screening, the predicted reduction in chlamydia prevalence in women aged 16-44 years ranged from 4% to 85%. Screening men and women had a greater impact than screening women alone in all models. There were marked differences between models in assumptions about treatment seeking and sexual behaviour before the start of the screening intervention.

CONCLUSIONS

Future models of chlamydia transmission should be fitted to both incidence and prevalence data. This meta-modelling study provides essential information for explaining differences between published studies and increasing the utility of individual-based chlamydia transmission models for policy making.

Modelling the effectiveness of chlamydia screening in England

BACKGROUND

Several developed countries have initiated chlamydia screening programmes. Screening for a sexually transmitted infection has both direct individual and indirect population-wide effects. Mathematical models can incorporate these non-linear effects and estimate the likely impact of different screening programmes and identify areas where more data are needed.

METHODS

A stochastic, individual based dynamic network model, parameterised from UK screening studies and data on sexual behaviour and chlamydia epidemiology, was used to investigate the likely impact of opportunistic screening on chlamydia prevalence. Three main strategies were considered for <25 year olds: (1) annual offer to women; (2) annual offer to women or if changed partner within last 6 months; (3) annual offer to men and women. Sensitivity analyses were performed for key screening parameters including uptake rate, targeted age range, percentage of partners notified, and screening interval.

RESULTS

Under strategy 1, continuous opportunistic screening of women <25 years of age is expected to reduce the population prevalence by over 50% after 5 years. Prevalence is also expected to decrease in unscreened older women and in men. For all three strategies screening those aged over 25 results in small additional reductions in prevalence. Including men led to a faster and greater reduction in overall prevalence, but involved approximately twice as many tests as strategy 1 and 10% more than strategy 2. The frequency of attendance at healthcare sites limits the number of opportunities to screen and the effect of changing the screening interval.

CONCLUSIONS

The model suggests that continuous opportunistic screening at high uptake rates could significantly reduced chlamydia prevalence within a few years. Opportunistic programmes depend on regular attendance at healthcare providers, but there is a lack of high quality data on patterns of attendance. Inequalities in coverage may result in a less efficient and less equitable outcome.

Investigating ethnic inequalities in the incidence of sexually transmitted infections: mathematical modelling study

OBJECTIVES

To investigate ethnic differences in rates of gonorrhoea using empirical sexual behaviour data in a simple mathematical model. To explore the impact of different intervention strategies in this simulated population.

METHODS

The findings from cross sectional studies of gonorrhoea rates and sexual behaviour in three ethnic groups in south east London were used to determine the parameters for a deterministic, mathematical model of gonorrhoea transmission dynamics, in a population stratified by sex, sexual activity (rate of partner change), and ethnic group (white, black African, and black Caribbean). We compared predicted and observed rates of infection and simulated the effects of targeted and population-wide intervention strategies.

RESULTS

In model simulations the reported sexual behaviours and mixing patterns generated major differences in the rates of gonorrhoea experienced by each subpopulation. The fit of the model to observed data was sensitive to assumptions about the degree of mixing by level of sexual activity, the numbers of sexual partnerships reported by men and women, and the degree to which observed data underestimate female infection rates. Interventions to reduce duration of infection were most effective when targeted at black Caribbeans.

CONCLUSIONS

Average measures of sexual behaviour in large populations are inadequate descriptors for the epidemiology of gonorrhoea. The consistency between the model results and empirical data shows that profound differences in gonorrhoea rates between ethnic groups can be explained by modest differences in a limited number of sexual behaviours and mixing patterns. Targeting effective services to particular ethnic groups can have a disproportionate influence on disease reduction in the whole community.

The impact of the phase of an epidemic of sexually transmitted infection on the evolution of the organism

The evolution of any sexually transmitted organism will be influenced by prevailing epidemiological interactions. The optimum strategy for an organism to overcome treatment, either through drug resistance or cryptic infections, depends upon whether the method for identifying patients is passive (treating symptoms alone favours asymptomatic organisms) or active (screening favours resistant organisms). The use of mathematical models of competing strains of infection allows theoretical predictions for the outcome of evolution under a range of assumptions about potential phenotypes. The course of pathogen evolution has implications for the success of interventions, but the predictions presented need to be tested at the level of the community in carefully monitored interventions.