Postoperative Time Out of Bed and Recovery of Walking Capacity After Colorectal Surgery
We welcome the opportunity to respond to the letter by Taito and Sarada, and appreciate their interest in our work. The letter raises issues regarding our actigraphy-based time out of bed data, adherence to other interventions within our enhanced recovery pathway (ERP), and reasons for nonadherence to early mobilization targets.
Previous literature assessing adherence to early mobilization relied on time out of bed data as self-reported by patients.1–4 This is the primary reason why we decided (a priori) to use self-reported data, rather than actigraphy, to assess whether patients achieved mobilization targets, so that our results could be compared to previous studies (see Supplement 1: Trial protocol and amendments).5 As mentioned in the “Discussion” section, we also suspect that our activity monitor tended to overestimate time out of bed by misclassifying patients as sitting out of bed when they were lying with the bed head elevated.5 This, in a post hoc manner, supported our decision not to use actigraphy-based data to define adherence to mobilization targets. Taito and Sarada suggest that we should have explored the association between mobilization parameters and recovery of walking capacity (Was functional walking capacity of patients who achieved mobilization targets better than that of patients who did not? Did time out of bed correlate positively with recovery of functional walking capacity?); however, we believe that little can be concluded from such analyses due to risk of confounding bias6 [ie, known and unknown patient factors that increase (or decrease) early mobilization may also influence postoperative waking capacity]. In other words, any post hoc analyses that are conducted beyond randomization cannot conclusively infer causality7; therefore, exploring such relationships would not contribute additional evidence regarding the impact of the intervention.
In our trial, patients in both groups were treated within a standardized ERP according to recommendations by the ERAS Society8; therefore, all patients received the same ERP elements except for the intervention of interest. Specific details about the ERP elements included in our program have been published elsewhere.9 Our ERP program for colorectal surgery was first implemented in 200610 and is currently well-established within our ward culture. For this reason, adherence to ERP elements in our center is higher1 when compared with centers that collected adherence data during an implementation phase.2–4,11 We do not have reasons to believe that adherence to ERP elements (other than early mobilization) were different between groups (see “Methods” section for strategies to prevent performance bias5); however, this was not directly measured for the purpose of this trial.
As Taito and Sarada indicated, around one-third of the patients in the intervention group did not adhere to the mobilization targets recommended. Reasons for nonadherence have been reported in Supplementary Table 4.5 From a total of 414 intervention sessions proposed (which included assistance with transfer to a chair, walking, and reinforcement of mobilization targets), the main reasons for nonadherence included patient refusal (n = 36), pain (n = 17), performing other procedure or examination (n = 8), late arrival at the ward (for sessions proposed on the day of surgery, n = 7), and orthostatic intolerance (n = 5). It is important to highlight that we did not expect patients to achieve perfect adherence because, after all, this trial was pragmatic and, therefore, aimed to assess the impact of the intervention in clinical practice under “real-life” conditions.