Cost of postoperative complications: How to avoid calculation errors

Table 2 Recommendations for the economic evaluations of costs associated with postoperative complications of surgical procedures

No.	Data to be described in the economic study
1	Type of study
2	Center: Particular characteristics
3	Period of inclusion of cases
4	Population and subgroups analyzed; clarify why they were chosen
5	Surgical interventions considered
6	Methods for managing the heterogeneity of the population and the surgical techniques used; clarify the possible influence of this heterogeneity on the results
7	If possible, describe the characteristics of the severity or complexity of patients (ASA, Charlson, Frailty ...)
8	Patients excluded and why
9	Patients and procedures lost for analysis. Economic data lost. Clarify whether these can compromise the validity of the results
10	Definition of complication
11	How complications are classified (better, Clavien-Dindo classification and comprehensive complication index)
12	Sources used to obtain data on the complications (specific forms, medical and nursing evolution comments)
13	Perspective from which the economic evaluation is carried out: the patient, the specific institution (e.g., the hospital), the target group for specific services e.g., rehabilitation), the Public Health Service, the Public Sector in general or from all perspectives (social perspective)
14	Health-related costs (direct and indirect), non-health-related costs (table 1). Sources used to obtain data. Specify the costs obtained en bloc (for example, general costs) those obtained in microcosts (radiology, pharmacy, ...) In the estimation of operating room costs, specify whether the cost of the consumable material used in each patient is individualized
15	Describe the postoperative follow-up time in which complications and costs will be evaluated for each perspective and procedure. From the hospital perspective, consider 90 d minimum
16	Methods for converting costs into a common monetary base and the exchange rate. If it includes more than one calendar year, specify corrections made for inflation
17	Biases and limitations of the study, and measures used to reduce them
18	Conflict of interests of researchers. Linking researchers to the surgical service and hospital
19	Source of study financing