Methodological Considerations for Cost of Illness Studies of Enteric Fever

The cost of typhoid illness in low- and middle-income countries, a scoping review of the literature

Typhoid fever is responsible for a substantial health burden in low- and middle-income countries (LMICs). New means of prevention became available with the prequalification of typhoid conjugate vaccines (TCV) by the World Health Organization (WHO) in 2018. Policymakers require evidence to inform decisions about TCV. The economic burden related to typhoid fever can be considerable, both for healthcare providers and households, and should be accounted for in the decision-making process. We aimed to understand the breadth of the evidence on the cost of typhoid fever by undertaking a scoping review of the published literature. We searched scientific databases with terms referring to typhoid fever cost of illness to identify published studies for the period January 1st 2000 to May 24th 2024. We also conferred with stakeholders engaged in typhoid research to identify studies pending completion or publication. We identified 13 published studies reporting empirical data for 11 countries, most of them located in Asia. The total cost of a typhoid episode ranged from $23 in India to $884 in Indonesia (current 2022 United States Dollar [USD]). Household expenditures related to typhoid fever were characterized as catastrophic in 9 studies. We identified 5 studies pending completion or publication, which will provide evidence for 9 countries, most of them located in Africa. Alignment in study characteristics and methods would increase the usefulness of the evidence generated and facilitate cross-country and regional comparison. The gap in evidence across regions should be mitigated when studies undertaken in African countries are published. There remains a lack of evidence on the cost to treat typhoid in the context of increasing antimicrobial resistance. Decision-makers should consider the available evidence on the economic burden of typhoid, particularly as risk factors related to antimicrobial resistance and climate change increase typhoid risk. Additional studies should address typhoid illness costs, using standardized methods and accounting for the costs of antimicrobial resistance.

Cost of illness due to respiratory syncytial virus acute lower respiratory tract infection among infants hospitalized in Argentina

BACKGROUND

Information is scarce regarding the economic burden of respiratory syncytial virus (RSV) disease in low-resource settings. This study aimed to estimate the cost per episode of hospital admissions due to RSV severe disease in Argentina.

METHODS

This is a prospective cohort study that collected information regarding 256 infants under 12 months of age with acute lower respiratory tract infection (ALRTI) due to RSV in two public hospitals of Buenos Aires between 2014 and 2016. Information on healthcare resource use was collected from the patient's report and its associated costs were estimated based on the financial database and account records of the hospitals. We estimated the total cost per hospitalization due to RSV using the health system perspective. The costs were estimated in US dollars as of December 2022 (1 US dollar = 170 Argentine pesos).

RESULTS

The mean costs per RSV hospitalization in infants was US$587.79 (95% confidence interval [CI] $535.24 - $640.33). The mean costs associated with pediatric intensive care unit (PICU) admission more than doubled from those at regular pediatric wards ($1,556.81 [95% CI $512.21 - $2,601.40] versus $556.53 [95% CI $514.59 - $598.48]).

CONCLUSIONS

This study shows the direct economic impact of acute severe RSV infection on the public health system in Argentina. The estimates obtained from this study could be used to inform cost-effectiveness analyses of new preventive RSV interventions being developed.

Vaccine value profile for Salmonella enterica serovar Paratyphi A

In Asia, there are an estimated 12 million annual cases of enteric fever, a potentially fatal systemic bacterial infection caused by Salmonella enterica serovars Typhi (STy) and Paratyphi A (SPA). The recent availability of typhoid conjugate vaccines (TCV), an increasing incidence of disease caused by SPA and growing antimicrobial resistance (AMR) across the genus Salmonella makes a bivalent STy/SPA vaccine a useful public health proposition. The uptake of a stand-alone paratyphoid vaccine is likely low thus, there is a pipeline of bivalent STy/SPA candidate vaccines. Several candidates are close to entering clinical trials, which if successful should facilitate a more comprehensive approach for enteric fever control. Additionally, the World Health Organization (WHO) has made advancing the development of vaccines that protect young children and working aged adults against both agents of enteric fever a priority objective. This "Vaccine Value Profile" (VVP) addresses information related predominantly to invasive disease caused by SPA prevalent in Asia. Information is included on stand-alone SPA candidate vaccines and candidate vaccines targeting SPA combined with STy. Out of scope for the first version of this VVP is a wider discussion on the development of a universal Salmonella combination candidate vaccine, addressing both enteric fever and invasive non-typhoidal Salmonella disease, for use globally. This VVP is a detailed, high-level assessment of existing, publicly available information to inform and contextualize the public health, economic, and societal potential of pipeline vaccines and vaccine-like products for SPA. Future versions of this VVP will be updated to reflect ongoing activities such as vaccine development strategies and "Full Vaccine Value Assessment" that will inform the value proposition of an SPA vaccine. This VVP was developed by an expert working group from academia, non-profit organizations, public-private partnerships, and multi-lateral organizations as well as in collaboration with stakeholders from the WHO South-East Asian Region. All contributors have extensive expertise on various elements of the VVP for SPA and collectively aimed to identify current research and knowledge gaps.

The Full Value of Vaccine Assessments (FVVA): a framework for assessing and communicating the value of vaccines for investment and introduction decision-making

BACKGROUND

Several economic obstacles can deter the development and use of vaccines. This can lead to limited product options for some diseases, delays in new product development, and inequitable access to vaccines. Although seemingly distinct, these obstacles are actually interrelated and therefore need to be addressed through a single over-arching strategy encompassing all stakeholders.

METHODS

To help overcome these obstacles, we propose a new approach, the Full Value of Vaccines Assessments (FVVA) framework, to guide the assessment and communication of the value of a vaccine. The FVVA framework is designed to facilitate alignment across key stakeholders and to enhance decision-making around investment in vaccine development, policy-making, procurement, and introduction, particularly for vaccines intended for use in low- and middle-income countries.

RESULTS

The FVVA framework has three key elements. First, to enhance assessment, existing value-assessment methods and tools are adapted to include broader benefits of vaccines as well as opportunity costs borne by stakeholders. Second, to improve decision-making, a deliberative process is required to recognize the agency of stakeholders and to ensure country ownership of decision-making and priority setting. Third, the FVVA framework provides a consistent and evidence-based approach that facilitates communication about the full value of vaccines, helping to enhance alignment and coordination across diverse stakeholders.

CONCLUSIONS

The FVVA framework provides guidance for stakeholders organizing global-level efforts to promote investment in vaccines that are priorities for LMICs. By providing a more holistic view of the benefits of vaccines, its application also has the potential to encourage greater take-up by countries, thereby leading to more sustainable and equitable impacts of vaccines and immunization programmes.

A consensus-based checklist for the critical appraisal of cost-of-illness (COI) studies

OBJECTIVES

To develop a consensus-based checklist that can be used as a minimum standard to appraise the comprehensiveness, transparency and consistency of cost-of-illness (COI) studies. This is important when, for instance, reviewing and assessing COI studies as part of a systematic review or when building an economic model.

METHODS

The development process of the consensus-based checklist involved six steps: (i) a scoping review, (ii) an assessment and comparison of the different checklists and their questions, (iii) the development of a (preliminary) checklist, (iv) expert interviews, (v) the finalization of the checklist, and (vi) the development of guidance statements explaining each question.

RESULTS

The result was a consensus-based checklist for the critical appraisal of COI studies, comprising seventeen main questions (and some additional subquestions) across three domains: (i) study characteristics; (ii) methodology and cost analysis; and (iii) results and reporting. Guidance statements were developed describing the purpose and meaning behind each question and listing examples of best practice. The following answer categories were suggested to be applied when answering the questions in the checklist: Yes, Partially, No, Not Applicable, or Unclear.

CONCLUSIONS

The consensus-based checklist for COI studies is a first step toward standardizing the critical appraisal of COI studies and is one that could be considered a minimum standard. The checklist can help to improve comprehensiveness, transparency and consistency in COI studies, to address heterogeneity, and to enable better comparability of methodological approaches across international studies.

Attributable Costs of Lung Cancer for the Colombian Health System: A Cost-of-Illness Study

OBJECTIVES

Lung cancer imposes a significant economic burden on most countries. Nevertheless, there is scarce information about this burden on health systems in low- and middle-income countries. This study aims to estimate the economic burden of lung cancer on the Colombian health system, a middle-income country with universal health coverage in Latin America.

METHODS

We conducted a cost-of-illness study that included all direct costs generated by prevalent cases of lung cancer in Colombia during 2017. We used administrative databases containing patient-level information on consumption of healthcare services and reports on healthcare spending published by the Colombian Ministry of Health. To decrease the probability of misallocation of costs, we used propensity score matching to estimate the marginal costs of delivering healthcare services to patients with lung cancer. Additionally, ordinary least squares and variations in case definitions were used to assess the robustness of all estimates.

RESULTS

Total costs attributable to lung cancer in 2017 ranged from $50 039 588 to $74 468 111, with important differences across insurance regimes (from $4 629 938 for the subsidized regime to $55 342 357 for the contributory regime). Notably, 43% of all costs ($27 081 348) were caused by the consumption of services not included in the health benefit package. There were no significant differences between inpatient and outpatient costs.

CONCLUSIONS

Lung cancer imposes a significant economic burden on the Colombian health system. Although all affiliates are entitled to a unique health benefit package, there were important differences in costs across insurance regimes. Further research is needed to identify the main mechanisms underlying these differences.