Study site

Da Nang, a class-1 municipality in Vietnam's central coastal region, spans 1,284.73 square kilometers. It serves as the hub for Central Vietnam's economy, culture, and education, with a population of 1,195,490 and an annual birth rate of 18.68 per thousand. In 2021, Da Nang's infant mortality rate was 8.19 per thousand live births, lower than the national average of 13.65 [21].

DNHWC is a tertiary hospital with 1,200 beds that serves three provinces and has 4.4 million people. The hospital oversees more than 15,000 annual births and specializes in high-risk pregnancies and sick children in the central region. DNHWC is nationally and internationally recognized for its expertise in breastfeeding practices, early essential newborn care, and kangaroo mother care [21].

The Da Nang HMB was established in February 2017. The establishment of this HMB involved various stakeholders, including the Ministry of Health, Da Nang City Department of Health, DNHWC, Alive & Thrive, PATH, and partners and consultants [9]. According to HMB monitoring data, as of July 31, 2023, this HMB had received 11,826 L of donor milk from 586 donors and administered pasteurized donor milk (PDM) to 31,736 newborns over 6.5 years. This HMB served newborns in need in this hospital as well as those in other hospitals in Da Nang city and provided pasteurized DHM to its satellite in Quang Nam province.

Costing approach

An activity-based costing (ABC) ingredient approach, which combines activity-based costing and ingredient methods, was employed. The ABC method defines the principal activities needed for the program [22, 23]. The ingredient approach involves identifying and costing out all the individual components or ingredients that go into a product or service [24]. We identified the types of inputs, such as building, furniture, equipment, vehicle depreciation, personnel, supplies, water, and electricity costs. We also determined the quantities of the inputs used by the program and the cost per unit of the inputs.

Four main groups of activities related to breastmilk donor involvement, milk handling, processing, milk usage, and general expenses were included in the running phase [9]. More specifically, activities related to breastmilk donor involvement included three processes: screening of donor mothers, selecting donor mothers, and preparing and managing empty containers for donor mothers. The activities related to breastmilk handling and processing included six processes: DHM pasteurization, screening, microbiological testing of pre- and post-pasteurization DHM samples, storage of raw and pasteurized DHM, DHM handling, and transportation. The activities related to DHM usage included two processes: estimating, requesting, and receiving pasteurized DHM and using pasteurized DHM. Finally, activities related to the general operation of the bank included 17 processes: standard of practice (SOP) composition and approval, cleaning and sterilizing instruments, handling HMB instruments, cleaning of functional rooms at the HMB, internal supervision, file storage and writing, detecting and solving incidents, pasteurizer and freezer operation and maintenance, refrigerator maintenance and operation, operation and maintenance of microbiological cultures, operation and maintenance of instrument cleaning, operation and maintenance of a mini autoclave, operation and maintenance of breast pumps, collection and transportation of DHM received from the community, label adherence, and handwashing. In other words, 28 activities were listed for cost calculation in the present study [9].

Cost perspective

The study's perspective determined which costs were relevant and should be included in the cost analysis, considering who bears the costs [24]. Costs for this first HMB in Vietnam were estimated from the perspective of the service provision agencies, including the HMB project, DNHWC, and other development partners.

Scope of cost

In this study, we estimated financial costs based on actual expenditures. Expenditure refers to the amount of money spent during a specific period. Costs reflect the resources needed to produce outputs/products during that period [25].

In this study, expenditure and financial costs (accounting costs) were obtained through expenditure reports and all related receipts. Financial costs represent actual expenditures on goods and services purchased. Financial costs were thus described in terms of how much money has been paid for the resources used [24]. This study excluded the opportunity costs incurred by patients and family members.

Phase of cost

Both start-up and implementation expenditures/costs were included. Start-up expenditures/costs were resources used for activities implemented between the decision to implement a program and the first time it provided DHM to a small vulnerable newborn [26]. Implementation expenditures/costs were resources used for routine activities.

Nature of costs

Both capital and recurrent expenditure/cost items were captured: Capital expenditures were one-time expenses to acquire assets, which were normally expensive (e.g., building, furniture, equipment, vehicles). Recurrent costs, including personnel, supplies, and operational expenses such as water and electricity, were incurred within a single financial or accounting year.

Function of costs

Both direct and indirect costs were measured. Direct costs were resources used for implementing the activities directly linked to the process of service delivery (donor involvement; DHM collection, handling, processing, and usage; and general operational expenses); indirect costs were resources used for activities that could not be attributed to a particular program, such as overhead and information, education, and communication activities. The costs included in this study are presented in Fig. 1.

Fig. 1

Costs included in this study

Data collection

The data were collected in 2016 and 2017 by a research team from the Center of Population Health Science, Hanoi University of Public Health. The team reviewed activity and expenditure reports to extract data on start-up activities and expenditures. For each activity, we identified costs by location and financial ingredient (e.g., staff cost, materials, supplies, transportation, building, equipment).

Field visits to DNHWC were conducted twice to collect data on implementation activities. In-depth interviews with HMB staff and direct observation of HMB procedures were performed during these field visits to calculate implementation costs.

Data management and analysis

The data were entered into a computer using Excel spreadsheets. Costs were presented in Vietnamese dong (VND) for expenses in Vietnam or in US dollars (USD) for expenses overseas. All costs were measured on June 15, 2023, in local currency units and converted to 2023 US dollars at an exchange rate of 1 USD = 23,881 VND, as announced by the State Bank of Vietnam [27].

The total monthly cost was estimated in two steps: Step 1 involved allocating expenditure from the start-up phase to the monthly start-up cost using useful years and the inflation rate, and step 2 involved adding the monthly implementation cost to the monthly start-up cost.

The unit cost is calculated as 1) cost per liter of pasteurized DHM that is suitable for use (i.e., meeting standards such as pre- and post-pasteurization tests, physiological appearance, and within expiration dates) and 2) cost per liter of DHM expressed by mothers (raw breastmilk) for international comparison purposes.

Three cost scenarios were examined (Table 1):

Scenario 1: Total costs (direct start-up costs + indirect start-up costs + implementation costs).

Scenario 2: Total direct costs (direct start-up costs + implementation costs).

Scenario 3: Total processing cost (capital costs + implementation costs).

Table 1 Three cost scenarios