Study design
A retrospective micro-costing study from January 2020 to November 2023 was conducted. It followed the methodological guideline recommended by the Brazilian Ministry of Health (13) and focused on financial data of RSV-related hospitalisations in a tertiary public hospital. We followed the principles of the ‘Reference Case for Estimating the Costs of Global Health Services and Interventions’ proposed by the Global Health Cost Consortium (14), as detailed in the Supplementary Table 1S.
Study context
The Brazilian Secretariat for Health and Environmental Surveillance (Secretaria de Vigilância em Saúde e Ambiente or SVSA) is critical for the surveillance and control of RSV disease, and other infectious diseases. The SVSA is responsible for coordinating efforts to detect, monitor, and respond to outbreaks by integrating data from hospitals and laboratories into the national epidemiological surveillance system. This system allows for near real-time monitoring of cases, which is essential for timely public health interventions, including implemention of preventive measures, public awareness campaigns, and vaccination programs where applicable (15). Additionally, Brazil participates in the Global Influenza Surveillance and Response System through its national influenza surveillance program. Since 2012, this program has included tracking severe acute respiratory syndrome caused by RSV as well (16).
In 2017, the Brazilian Society of Pediatrics released the national guideline for managing RSV infection (17). The Brazilian Ministry of Health has recently updated the national guideline for managing RSV infection, which includes prophylactic approaches, such as administration of palivizumab (Synagis®). This is the only product currently available in the SUS to prevent RSV infections (18). Three more products have recently been approved by the Brazilian regulatory agency (Agência Nacional de Vigilância Sanitária - Anvisa). Nirsevimab (Beyfortus®) is recommended for prevention of RSV-ALRI in newborns and children under 24 months (19). The Arexvy® vaccine is indicated for the prevention of ALRI caused by RSV-A and RSV-B subtypes in adults aged 60 years and older (20). The Abrysvo® vaccine is indicated for the prevention of ALRI and severe ALRI caused by RSV-A and RSV-B in children from birth to 6 months of age by active immunization of pregnant women, and in individuals 60 years of age and older by active immunization (21). However, these products are not currently incorporated in the SUS. Therefore, it is critical to understand the financial impact of RSV-associated ALRI for future economic evaluations of new products to prevent infections caused by RSV in Brazil.
Study population
The data for this study came from the Hospital Municipal Vila Santa Catarina (HMVSC), a tertiary public hospital in Brazil. We selected the hospital based on three criteria: it is part of the Unified Healthcare System, it has a high number of RSV cases, and it has structured financial data available. The HMVSC is part of the philanthropic society network administration named Sociedade Beneficente Israelita Brasileira Albert Einstein. It covers a population of 2.6 million individuals in São Paulo city, in the Southeastern region of Brazil. The HMVSC has 193 operational beds, including 30 adult intensive care unit (ICU) beds and nine paediatric/neonatal ICU beds.
Included in the study were hospitalized ALRI paediatric patients younger than 1 year of age (up to 11 months and 29 days) with a positive RSV isolate detected by a molecular respiratory panel test. Not included were patients with other types of hospitalisations unrelated to viral respiratory infection, infections acquired after hospital admission to HMVSC (i.e., symptoms starting 48 hours after admission), more than one respiratory virus detected in a molecular respiratory panel test (including RSV with coinfections), and missing data (e.g., detailed per-patient cost data). The temporal framework for this study was anchored to the implementation of the electronic surveillance system in the HMVSC institutional network, which started in January 2020. Cases from January 2020 through November 30, 2023 were included.
Data preparation
Data on age, utilization of intensive care, date and time of admission, and molecular viral respiratory panel results were extracted. Admission was defined as the use of a hospital bed for at least 24 hours. The Financial Department of the philanthropic network where HMVSC is embedded supervised this critical collection stage, ensuring full compliance with all data protection laws. Data was extracted using the platform for care and qualitative data Cerner Millennium System – Medical Suite and the financial data system SAP®. No case had to be excluded from analysis due to missing data.
Once de-identified, the fixed cost (FC) and variable cost (VC) of the reported medical care were extracted for each participant and validated at a granular level of medical records, hospital admissions, and consumer items. Each participant was assigned a unique code, ensuring a distinct and accurate financial record for each hospital admission, preventing any duplication or double-counting of costs.
Fixed cost are expenses that do not depend on the number of patients or care provided; they depend on hospital capacity (i.e., salaries of professionals, depreciation, inputs, supplies, commonly used medications, and maintenance costs of the facilities). In contrast, VC refers to those expenses that are directly dependent on the medical care provided to each patient. The VC appropriation of materials and medicines is based on the moving average price. The total cost (total cost = FC + VC) of each patient was estimated using these data.
The bed cost per day comprised salaries/wages of physicians, nurses, and nurse technicians, external consultations, vacation provision, social charges, 13th salary provision, night shifts, gratuity, health insurance plan and in-house medical assistance, sick leave, food vouchers and meals, employee transportation, compensations/agreements, service time guarantee fund, health assistance for dependents, dental insurance plan, overtime, social integration program and service time guarantee fund without vacation, ‘Mais Vida’ program, and pharmacy benefits. Other costs related to the bed cost per day were for administrative resources, electricity and water supply, and general services including nutrition, maintenance, cleaning, linen items, pharmacy, and security.
Costs attributable to some professional services, such as physical therapy, psychology and occupational therapy, are not included in the bed cost per day and were considered separately, for they had been accounted for in exclusive cost centres and items.
Cost analysis
In all cases, the cost calculation for RSV hospitalisation considered FC and VC for direct medical and overhead costs involved in providing care and assistance. The direct medical costs include all expenses directly associated with patient care, covering materials, drugs, laboratory tests, medical procedures. Overhead costs are expenses that are not directly related to care but are essential for the provision of medical assistance. These include human resources (such as salaries and benefits for healthcare professionals), expenses linked to infrastructure (like rent, utilities, and maintenance), and other institutional costs required for providing care. We calculated the estimated average cost (AC) per hospitalisation by applying this financial information (i.e., total cost and total hospital admission), employing a designated formula:
$$\:Average\:hospitalization\:cost=\:\frac{\:Hospitalization\:cost}{\:Hospital\:admission}$$
Equation 1. The average cost of hospitalisation per patient
The denominator represents the observed hospital occupation. Maximum hospital occupations were not calculated.
The average length of stay (LOS) in days was also recorded. Thus, we also estimated the AC per day:
$$\:Average\:cost\:per\:day\:=\:\frac{\:Hospitalization\:cost\:}{\:Length\:of\:stay\:\left(in\:days\right)}$$
Equation 2. The average cost of hospitalisation per day
The bottom-up absorption model was used following the Brazilian micro-costing guidelines (13). Absorption costing is the method that consists of providing products all production costs, direct or indirect, fixed or variable. One characteristic of the method is the distribution of indirect accounting costs, which are related to support areas, through apportionment criteria defined a priori (13).
Results are presented in tables and figures summarising the main findings. Additionally, the aggregate AC by age group and with and without ICU use are presented in a box-plot graphic. The main expenses by category are presented in a Tornado plot. Parametric assumptions were evaluated against normal plots, and the U Mann-Whitney test was used to compare groups. Aggregate AC was correlated with average LOS, and Spearman’s rank test was calculated. The significance level was set to ∂ = 5%. The graphs and statistical analysis were performed using Visual Studio Code, version 1.86.0 (USA), Power BI, version 2.128.1177 (USA), and Python, version 3.11.7 (USA).
This study reports all values in Brazilian reais (BRL), followed by conversion to United States dollars using purchasing power parity (USD-PPP) based on the Organisation for Economic Co-operation and Development (OECD) conversion of the last corresponding year: 2023 (USD-PPP 1 = BRL 2.43) (22).