Imperial College London

Dr Kelsey Case

Faculty of MedicineSchool of Public Health

Honorary Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 1524k.case

 
 
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Location

 

LG33BPraed StreetSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
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15 results found

Mahiane SG, Eaton J, Glaubius R, Case KK, Sabin K, Marsh Ket al., 2021, Updates to Spectrum’s Case Surveillance and Vital Registration tool for HIV estimates and projections, Journal of the International AIDS Society, ISSN: 1758-2652

Introduction: The Case Surveillance and Vital Registration (CSAVR) model within Spectrum estimates HIV incidence trends from surveillance data on numbers of new HIV diagnoses and HIV-related deaths. This article describes developments of the CSAVR tool to more flexibly model diagnosis rates over time, estimate incidence patterns by sex and age group, and by key population group. Methods: We modelled HIV diagnosis rate trends as a mixture of three factors, including temporal and opportunistic infection components. The tool was expanded to estimate incidence rate ratios by sex and age for countries with disaggregated reporting of new HIV diagnoses and AIDS deaths, and to account for information on key populations such as men who have sex with men (MSM), males who inject drugs (MWID), female sex workers (FSW) and females who inject drugs (FWID). We used a Bayesian framework to calibrate the tool in 71 high-income or low HIV burden countries. Results: Across countries, an estimated median 89% (interquartile range [IQR] 78%-96%) of HIV-positive adults knew their status in 2019. Mean CD4 counts at diagnosis were stable over time, with a median of 456 cells/μl (IQR: 391-508) across countries in 2019. In European countries reporting new HIV diagnoses among key populations median estimated proportions of males that are MSM and MWID was 1.3% (IQR: 0.9%- 2.0%) and 0.56% (IQR: 0.51%- 0.64%), respectively. The median estimated proportions of females that are FSW and FWID were 0.36% (IQR: 0.27%-0.45%) and 0.14 (IQR: 0.13%- 0.15%), respectively. HIV incidence per 100 person-year increased among MSM with median estimates reaching 0.43 (IQR: 0.29-1.73) in 2019, but remained stable in MWID, FSW and FWID, at around 0.12 (IQR: 0.04-1.9), 0.09 (IQR: 0.06-0.69) and 0.13% (IQR: 0.08%-0.91%) in 2019, respectively. Knowledge of HIV status among HIV-positive adults gradually increased since the early 1990s to exceed 75% in more than 75% of countries in 2019 among each key population. Con

Journal article

Whittaker R, Case KK, Nilsen Ø, Blystad H, Cowan S, Kløvstad H, van Sighem Aet al., 2020, Monitoring progress towards the first UNAIDS 90-90-90 target in key populations living with HIV in Norway, BMC Infectious Diseases, Vol: 20, Pages: 1-11, ISSN: 1471-2334

BackgroundIn line with the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 target, Norway aims for at least 90% of people living with HIV (PLHIV) to know their HIV-status. We produced current estimates of the number of PLHIV and undiagnosed population in Norway, overall and for six key subpopulations: Norwegian-born men who have sex with men (MSM), migrant MSM, Norwegian-born heterosexuals, migrant Sub-Saharan Africa (SSA)-born heterosexuals, migrant non-SSA-born heterosexuals and people who inject drugs.MethodsWe used the European Centre for Disease Prevention and Control (ECDC) HIV Modelling Tool on Norwegian HIV surveillance data through 2018 to estimate incidence, time from infection to diagnosis, PLHIV, and the number and proportion undiagnosed. As surveillance data on CD4 count at diagnosis were not collected in Norway, we ran two models; using default model CD4 assumptions, or a proxy for CD4 distribution based on Danish national surveillance data. We also generated alternative overall PLHIV estimates using the Spectrum AIDS Impact Model, to compare with those obtained from the ECDC tool.ResultsEstimates of the overall number of PLHIV in 2018 using different modelling approaches aligned at approximately 5000. In both ECDC models, the overall number undiagnosed decreased continuously from 2008. The proportion undiagnosed in 2018 was lower using default model CD4 assumptions (7.1% [95%CI: 5.3–8.9%]), than the Danish CD4 proxy (10.2% [8.3–12.1%]). This difference was driven by results for heterosexual migrants. Estimates for Norwegian-born MSM, migrant MSM and Norwegian-born heterosexuals were similar in both models. In these three subpopulations, incidence in 2018 was < 30 new infections, and the number undiagnosed had decreased in recent years. Norwegian-born MSM had the lowest estimated number of undiagnosed infections (45 [30–75], using default CD4 assumptions) and undiagnosed fraction (3.6% [2.4–5.7%], using de

Journal article

Case K, Johnson L, Mahy M, Marsh K, Supervie V, Eaton Jet al., 2019, Summarizing the results and methods of the 2019 Joint United Nations Programme on HIV/AIDS HIV estimates, AIDS, Vol: 33, Pages: S197-S201, ISSN: 0269-9370

UNAIDS and other partners provide support to countries to develop estimates of HIV and related indicators on an annual basis. These estimates are used to monitor epidemic trends, guide program planning and resource allocation, and inform policy decision-making. The collection of articles in this AIDS supplement provide the headline results for the 2019 UNAIDS estimates and describe the new developments in the methods used to produce these estimates.

Journal article

Case K, Gomez G, Hallett T, 2019, The impact, cost and cost-effectiveness of oral pre-exposure prophylaxis in sub-Saharan Africa: a scoping review of modelling contributions and way forward, Journal of the International AIDS Society, Vol: 22, ISSN: 1758-2652

Introduction: Oral pre-exposure prophylaxis (PrEP) is a new form of HIV prevention being considered for inclusion in national prevention portfolios. Many mathematical modelling studies have been undertaken that speak to the impact, cost and cost-effectiveness of PrEP programmes. We assess the available evidence from mathematical modelling studies to inform programme planning and policy decision making for PrEP and further research directions.Methods: We conducted a scoping review of the published modelling literature. Articles published in English which modelled oral PrEP in sub-Saharan Africa, or non-specific settings with relevance to generalised HIV epidemic settings, were included. Data were extracted for the strategies of PrEP use modelled, and the impact, cost and cost-effectiveness of PrEP for each strategy. We define an algorithm to assess the quality and relevance of studies included, summarise the available evidence and identify the current gaps in modelling. Recommendations are generated for future modelling applications and data collection.Results and discussion: We reviewed 1,924 abstracts and included 44 studies spanning 2007 to 2017. Modelling has reported that PrEP can be a cost-effective addition to HIV prevention portfolios for some use cases, but also that it would not be cost-effective to fund PrEP before other prevention intervention are expanded. However, our assessment of the quality of the modelling indicates cost-effectiveness analyses failed to comply with standards of reporting for economic evaluations and the assessment of relevance highlighted that both key parameters and scenarios are now outdated. Current evidence gaps include modelling to inform service development using updated programmatic information and ex post modelling to evaluate and inform efficient deployment of resources in support of PrEP, especially among key populations, using direct evidence of cost, adherence and uptake patterns.Conclusions: Updated modelling which more

Journal article

McRobie ES, Matovu F, Nanyiti A, Nonvignon J, Abankwah D, Case K, Hallett TB, Hanefeld J, Conteh Let al., 2017, National responses to global health targets: Exploring policy transfer in the context of the UNAIDS '90-90-90' treatment targets in Ghana and Uganda, Health Policy and Planning, Vol: 33, Pages: 17-33, ISSN: 1460-2237

Global health organizations frequently set disease-specific targets with the goal of eliciting adoption at the national-level; consideration of the influence of target setting on national policies, programme and health budgets is of benefit to those setting targets and those intended to respond. In 2014, the Joint United Nations Programme on HIV/AIDS set ‘ambitious’ treatment targets for country adoption: 90% of HIV-positive persons should know their status; 90% of those on treatment; 90% of those achieving viral suppression. Using case studies from Ghana and Uganda, we explore how the target and its associated policy content have been adopted at the national level. That is whether adoption is in rhetoric only or supported by programme, policy or budgetary changes. We review 23 (14 from Ghana, 9 from Uganda) national policy, operational and strategic documents for the HIV response and assess commitments to ‘90–90–90’. In-person semi-structured interviews were conducted with purposively sampled key informants (17 in Ghana, 20 in Uganda) involved in programme-planning and resource allocation within HIV to gain insight into factors facilitating adoption of 90–90–90. Interviews were transcribed and analysed thematically, inductively and deductively, guided by pre-existing policy theories, including Dolowitz and Marsh’s policy transfer framework to describe features of the transfer and the Global Health Advocacy and Policy Project framework to explain observations. Regardless of notable resource constraints, transfer of the 90–90–90 targets was evident beyond rhetoric with substantial shifts in policy and programme activities. In both countries, there was evidence of attempts to minimize resource constraints by seeking programme efficiencies, prioritization of programme activities and devising domestic financing mechanisms; however, significant resource gaps persist. An effective health network, comprised

Journal article

Case KK, Gregson S, Mahy M, Ghys PD, Hallett TBet al., 2017, Editorial: methodological developments in the Joint United Nations Programme on HIV/AIDS estimates, AIDS, Vol: 31, Pages: S1-S4, ISSN: 0269-9370

The Joint United Nations Programme on HIV/AIDS (UNAIDS) publishes estimates of the HIV epidemic every year [1]. For 2016, estimates are available for 160 countries representing 98% of the global population. These estimates are produced by countries with guidance from UNAIDS. The methods used in this process continue to evolve over time under the stewardship of the UNAIDS Reference Group on Estimates, Modelling and Projections [2].In 2014, the WHO convened the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER) Working Group with the aim to define and promote good practice in reporting global health estimates [3]. The GATHER Statement is the outcome produced by this group. It defines a list of reporting requirements to allow for the accurate interpretation, and facilitate the appropriate use, of global health estimates [4]. UNAIDS fully endorses and supports the GATHER Statement.The current special supplement, which details the methods used to produce the 2016 UNAIDS estimates, further supports the routine publication of data sources and methods used as part of an open and transparent process. It provides updates of the evolving understanding of the data on which the estimates are based, the methods used to derive the estimates, justification of changes in these methods, and the sources of new data available to inform these modifications. It follows a series of such collections [5–10] which have documented and described the evolving methods used to produce the UNAIDS Global AIDS estimates since 2004.

Journal article

Silhol R, Gregson S, Nyamukapa C, Mhangara M, Dzangare J, Gonese E, Eaton JW, Case KK, Mahy M, Stover J, Mugurungi Oet al., 2017, Empirical validation of the UNAIDS Spectrum model for subnational HIV estimates: case-study of children and adults in Manicaland, Zimbabwe, AIDS, Vol: 31, Pages: S41-S50, ISSN: 0269-9370

Background: More cost-effective HIV control may be achieved by targeting geographical areas with high infection rates. The AIDS Impact model of Spectrum – used routinely to produce national HIV estimates – could provide the required subnational estimates but is rarely validated with empirical data, even at a national level.Design: The validity of the Spectrum model estimates were compared to empirical estimates.Methods: Antenatal surveillance and population survey data from a population HIV cohort study in Manicaland, east Zimbabwe, were input into Spectrum 5.441 to create a simulation representative of the cohort population. Model and empirical estimates were compared for key demographic and epidemiological outcomes. Alternative scenarios for data availability were examined and sensitivity analyses were conducted for model assumptions considered important for subnational estimates.Results: Spectrum estimates generally agreed with observed data but HIV incidence estimates were higher than empirical estimates while estimates of early age all-cause adult mortality were lower. Child HIV prevalence estimates matched well with the survey prevalence among children. Estimated paternal orphanhood was lower than empirical estimates. Including observations from earlier in the epidemic did not improve the HIV incidence model fit. Migration had little effect on observed discrepancies - possibly because the model ignores differences in HIV prevalence between migrants and residents.Conclusions: The Spectrum model, using subnational surveillance and population data, provided reasonable subnational estimates although some discrepancies were noted. Differences in HIV prevalence between migrants and residents may need to be captured in the model if applied to subnational epidemics.

Journal article

Lalla-Edward ST, Fobosi SC, Hankins C, Case K, Venter WDF, Gomez Get al., 2016, Healthcare Programmes for Truck Drivers in Sub-Saharan Africa: A Systematic Review and Meta-Analysis, PLOS One, Vol: 11, ISSN: 1932-6203

BackgroundTruck drivers have unique health needs, and by virtue of their continuous travel, experiencedifficulty in accessing healthcare. Currently, planning for effective care is hindered by lackof knowledge about their health needs and about the impact of on-going programmes onthis population’s health outcomes. We reviewed healthcare programmes implemented forsub-Saharan African truck drivers, assessed the evaluation methods, and examined impacton health outcomes.MethodsWe searched scientific and institutional databases, and online search engines to include allpublications describing a healthcare programme in sub-Saharan Africa where the main clientswere truck drivers. We consulted experts and organisations working with mobile populationsto identify unpublished reports. Forest plots of impact and outcome indicators withunadjusted risk ratios and 95% confidence intervals were created to map the impact ofthese programmes. We performed a subgroup analysis by type of indicator using a randomeffectsmodel to assess between-study heterogeneity. We conducted a sensitivity analysisto examine both the summary effect estimate chosen (risk difference vs. risk ratio) andmodel to summarise results (fixed vs. random effects).ResultsThirty-seven publications describing 22 healthcare programmes across 30 countries wereincluded from 5,599 unique records. All programmes had an HIV-prevention focus withonly three expanding their services to cover conditions other primary healthcare services.Twelve programmes were evaluated and most evaluations assessed changes in input, output, and outcome indicators. Absence of comparison groups, preventing attribution ofthe effect observed to the programme and lack of biologically confirmed outcomes were themain limitations. Four programmes estimated a quantitative change in HIV prevalenceor reported STI incidence, with mixed results, and one provided anecdotal evidence ofchanges in AIDS-related mortality and social norms. Most programmes sho

Journal article

Stover J, Hallett TB, Wu Z, Warren M, Gopalappa C, Pretorius C, Ghys PD, Montaner J, Schwartlander Bet al., 2014, How Can We Get Close to Zero? The Potential Contribution of Biomedical Prevention and the Investment Framework towards an Effective Response to HIV, PLOS One, Vol: 9, ISSN: 1932-6203

Background: In 2011 an Investment Framework was proposed that described how the scale-up of key HIV interventionscould dramatically reduce new HIV infections and deaths in low and middle income countries by 2015. This frameworkincluded ambitious coverage goals for prevention and treatment services resulting in a reduction of new HIV infections bymore than half. However, it also estimated a leveling in the number of new infections at about 1 million annually after 2015.Methods: We modeled how the response to AIDS can be further expanded by scaling up antiretroviral treatment (ART)within the framework provided by the 2013 WHO treatment guidelines. We further explored the potential contributions ofnew prevention technologies: ‘Test and Treat’, pre-exposure prophylaxis and an HIV vaccine.Findings: Immediate aggressive scale up of existing approaches including the 2013 WHO guidelines could reduce newinfections by 80%. A ‘Test and Treat’ approach could further reduce new infections. This could be further enhanced by afuture highly effective pre-exposure prophylaxis and an HIV vaccine, so that a combination of all four approaches couldreduce new infections to as low as 80,000 per year by 2050 and annual AIDS deaths to 260,000.Interpretation: In a set of ambitious scenarios, we find that immediate implementation of the 2013 WHO antiretroviraltherapy guidelines could reduce new HIV infections by 80%. Further reductions may be achieved by moving to a ‘Test andTreat’ approach, and eventually by adding a highly effective pre-exposure prophylaxis and an HIV vaccine, if they becomeavailable.

Journal article

Hallett TB, Zaba B, Stover J, Brown T, Slaymaker E, Gregson S, Wilson DP, Case KKet al., 2014, Embracing different approaches to estimating HIV incidence, prevalence and mortality, AIDS, Vol: 28, Pages: S523-S532, ISSN: 0269-9370

Journal article

Case KK, Hallett TB, Gregson S, Porter K, Ghys PDet al., 2014, Development and future directions for the Joint United Nations Programme on HIV/AIDS estimates, AIDS, Vol: 28, Pages: S411-S414, ISSN: 0269-9370

Journal article

Gomez GB, Borquez A, Case KK, Wheelock A, Vassall A, Hankins Cet al., 2013, The Cost and Impact of Scaling Up Pre-exposure Prophylaxis for HIV Prevention: A Systematic Review of Cost-Effectiveness Modelling Studies, PLoS Med, Vol: 10

<p>Gabriela Gomez and colleagues systematically review cost-effectiveness modeling studies of pre-exposure prophylaxis (PrEP) for preventing HIV transmission and identify the main considerations to address when considering the introduction of PrEP to HIV prevention programs.</p>

Journal article

Case KK, Ghys PD, Gouws E, Eaton JW, Borquez A, Stover J, Cuchi P, Abu-Raddad LJ, Garnett GP, Hallett TBet al., 2012, Understanding the modes of transmission model of new HIV infection and its use in prevention planning, BULLETIN OF THE WORLD HEALTH ORGANIZATION, Vol: 90, Pages: 831-838, ISSN: 0042-9686

Journal article

Hecht R, Stover J, Bollinger L, Muhib F, Case K, de Ferranti Det al., 2010, Financing of HIV/AIDS programme scale-up in low-income and middle-income countries, 2009–31, The Lancet, Vol: 376, Pages: 1254-1260, ISSN: 0140-6736

Journal article

Eaton JW, Garnett GP, Ghys PD, Case KK, Mahy Met al., 2010, Measuring concurrent partnerships reply, LANCET, Vol: 375, Pages: 1870-1870, ISSN: 0140-6736

Journal article

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