| Part of review process |
Description of potential minor bias |
| Developing the review question |
When choosing the proportion of participants requiring 'rescue' analgesia as one of our secondary outcomes, we overlooked that this outcome might not be meaningful with a design focusing on abdominal surgery. This surgical procedure probably will for almost all participants create some need for 'rescue' analgesia, and hence, a difference between intervention groups regarding this outcome could hardly be detected. After realising this, we could have chosen to exclude this outcome, but this would make a post hoc decision after analysis of results. Had we chosen to exclude this outcome, it would have entailed exclusion of the study by Khanduja 2013, as the study did not report other relevant outcomes for our review |
| Collecting data |
One of our included studies was available only in Chinese (Xiao 2013), and because our review was not funded financially, we did not purchase a professional and full translation, but only extraction of data (see Appendix 6) performed on a voluntary basis by a medical expert in native Chinese within The Cochrane Collaboration. Data from tables were extracted by the first and second authors of this review, but regarding assessment of risk of bias, the study was evaluated by only one person (the translator). However, because the study reported very little information about randomization, allocation, blinding, etc, risk of bias introduced in the review process probably was of minor importance. We contacted the Chinese authors for details in English, without reply |
| To keep focus on outcomes with importance for patients, we chose to collect data about heart rate and blood pressure only if they required intervention. Therefore, reports of e.g. significant differences in heart rate or blood pressure have not been collected, unless bradycardia or hypotension requiring intervention was reported. This decision may have led to underreporting of side effects among studies inasmuch as one can imagine that a study reporting a significant difference in heart rate may have omitted data about number of participants when intervention was needed |
| Presenting results |
To make the 'Summary of findings' table as simple as possible, we decided to report only our primary outcomes at the time point 24 hours after surgery. This decision may have represented selective reporting and hence introduced risk of bias, inasmuch as the decision was made after completion of data and analyses. However, all data with all time points were presented in Data and analyses and Table 4 and were also mentioned in several sections |
| Assessing risk of bias |
Assessment of 'high risk of other bias' for Tufanogullari 2008 can be debated (see Characteristics of included studies). This is beyond doubt a well‐conducted study with low risk of bias for all other domains, and other reviews have assessed only the study with the highest of quality scores (Blaudszun 2012; Schnabel 2013). We tried to contact study authors to request additional information about the three‐step 'rescue' analgesia regimen, without success |
