Table 1 Steps in the process of developing Efficacy –Safety Score (ESS)

1.

Comprehensive literature review to identify current postoperative scales and scores to determine their limitations.

2.

Identification of aspects of interest regarding postoperative patients based on empirical experience.

3.

Pilot study (n = 182) with the prototype score to identify possibilities and pitfalls for a novel tool for postoperative use [9, 10].

4.

Identification through a Delphi-project the aspects considered relevant for clinicians to make a postoperative assessment [11]. Table 2.

5.

Refining the score and system after pilot study and Delphi-project.

6.

Writing of a protocol and conducting of a validation study in 207 patients.

7.

Validation of the ESS against the criteria set by Terwee et al. [14] Table 4.