After performing all the steps required for the implementation of the ABC model, the total costs of the provided services in the CT-scan unit of Shahid Rajaei Teaching Hospital were calculated. The present study was the first in recent years to use ABC in the CT-scan unit of Shahid Rajaei Hospital. According to the findings regarding the total costs of the CT-scan unit in the study period, the direct costs were 81.3% higher than the indirect costs (18.7%). Nisenbaum et al. conducted a similar study in the CT-scan section, and the obtained results indicated that the share of the direct costs was higher than the indirect costs (
18). Considering that indirect costs are fixed, their high values could indicate the improper utilization of organizational capacities (
16). In contrast, the high ratio of the direct costs to the indirect costs showed the optimal use of the available resources to provide more services (
14). In order to exploit the available capacities, the number of available services should increase, and the ratio of the indirect costs should be minimized.
In the present study, the personnel costs and costs of the consumed materials were highest, while the overhead costs were lowest. Our findings regarding the share of each cost element of the total costs are consistent with the studies conducted by Bahadori et al. and Nisenbaum et al. In the mentioned studies, the highest share of costs was related to personnel costs (
14,
18). In contrast to the results of the present study, Mouseli et al. calculated the total costs of laboratory services, reporting the costs of the consumed materials (37%) to be higher than the costs of human resources (36.3%) (
15).
According to the present study, the costs of the consumed materials were higher than the costs of the consumed materials in the research conducted by Kalhor et al. (
2) (4%) and Anzai et al. (
8) (14%). This discrepancy could be due to the differences in the research population, costing methods, and accuracy level of the financial information in various studies.
In our study, the overhead costs included the energy carrier costs, building depreciation costs, assets depreciation costs, maintenance costs, and costs that were allocated to the support and administrative units. The share of the overhead costs varies in different studies; Kalhor et al. (
2) reported the share of overhead costs to be 37%, while the share of the overhead costs in the study by Anzai et al. (
8) was 6.4% .
Depreciation is a significant amount in the category of indirect costs, most of which was attributed to CT-scan depreciation. The reported depreciation value vary in different studies. The number and Rial value of medical equipment, office supplies, and other assets were the cause of the difference in the calculated depreciation cost in different units.
Among the cost elements, the least amount belonged to energy, with the highest cost related to the consumed power due to the frequent use of CT-scan devices. Mouseli et al. also attributed the lowest share to this cost element (
15). The defined drivers, number of the devices, area and number of the personnel of the units, and type of the costing method could also affect the total costs.
The comparison of the results of the present study with the approved tariffs during the study period indicated no significant difference between the total price calculated by the ABC method and tariffs of the services (P ≥ 0.05), and the mean tariffs was higher than the mean cost of the services, while the paid tariff was higher than the total price in at least 24 services. In other words, the tariffs paid by insurance organizations were close to the total costs of the CT-scan services during the study period. In this regard, Bayati et al. estimated the costs of the MRI unit to be less than the tariffs approved during their study (
6). In addition to the differences in the study populations, this discrepancy could be due to the revisions on the tariffs approved by the Ministry of Health in recent years. The current research showed that the claim of some organizations that tariffs are not realistic at present was untrue, and that new reforms should be applied in their costing and cost control systems.
5.1. Conclusion
According to the results, the costs of the CT-scan services were lower than the tariffs approved by the Ministry of Health. Therefore, the revenue of the CT-scan unit in the study period was higher than the costs, which made the unit profitable. Therefore, it could be predicted that with cost reduction, the unit will reach more profitability, and the outsourcing of the CT-scan services in this center will fail.
5.2. Limitations of the Study
1) Failure to provide accurate information by the authorities due to the inadequate knowledge of the study methodology;
2) Lack of proper infrastructures to accurately record the costs;
3) Lack of proper infrastructures for the accurate calculation and recording of the energy costs;
4) Due to the need to study at the end of the fiscal year, the performed activities during the study period were not recorded, and the probability of error in identifying the activities increased.