Description

1. Background and rationale Minimally invasive techniques for colorectal surgery include standard laparoscopy and robot-assisted laparoscopy. Studies evaluating recovery after anaesthesia and surgery have focused primarily on physiological endpoints, recovery times, and the incidence of adverse events, such as major morbidity and mortality. Although these parameters are essential and should be measured, they mostly ignore the patient's perspective. Patient-related outcomes can be assessed with tools designed for that purpose, such as the Quality of Recovery-15 (QoR-15) questionnaire.

This single-centre prospective observational cohort study will compare robotic vs laparoscopic colorectal resections with the primary outcome of QoR-15 at 24 hours after surgery, capturing anaesthesia-specific variables to adjust for confounding. 2. Objectives Primary objective: To compare patient-reported quality of recovery (QoR-15 total score) at 24 hours postoperatively between patients undergoing surgeon-allocated robotic vs laparoscopic colorectal surgery following ERAS protocol.

Secondary objectives:

• Compare QoR-15 at PACU discharge and at 48h.
• Compare pain scores, opioid consumption (first 24 and 48 h), PONV rates, PACU time, intraoperative hemodynamic instability events, length of hospital stay, complications (Clavien-Dindo), and 30-day readmission. 3. Study design Prospective, single-centre, observational cohort study. Allocation to robotic vs laparoscopic is determined by the operating surgeon (non-randomised). The anaesthetist will enrol and collect preop, intraop and postop data. Statistical methods will adjust for confounding (propensity-score methods, multivariable regression, clustering by surgeon). 4. Inclusion / exclusion criteria Inclusion: Age ≥ 18 years, scheduled for elective colorectal resection (laparoscopic or robot-assisted), ASA I-III, able to consent and complete QoR-15, included in ERAS pathway.

Exclusion: Emergency surgery, concomitant major non-colorectal procedure, severe cognitive impairment, refusal/inability to consent. 5. Outcomes and definitions Primary outcome: QoR-15 total score (0-150) at 24 hours after surgery (±4 h window). Secondary outcomes: QoR-15 at PACU, 48/72 h; pain scores; opioid use; PONV; PACU and OR times; intraop hemodynamics; LOS; complications; 30-day readmission. 6. Anaesthesia recommendations and recording Standardized induction (propofol, fentanyl, rocuronium), maintenance (TIVA), multimodal analgesia, and antiemetic prophylaxis. All drugs, doses, fluid management, temperature, and monitoring to be recorded. 7. Data collection (CRF) Detailed CRF variable list includes baseline demographics, comorbidities, preop QoR-15, surgical and anaesthetic details, intraop events, PACU data, postoperative QoR-15, pain, PONV, complications, and LOS. Use validated QoR-15 translation, time-stamp each administration. 8. Sample size and power According to the previous literature, the standard deviation (SD) of the total QoR-15 score in the Portuguese population is 14 \[7\]. An 8-point difference in the QoR-15 score represents the MCID that defines if the quality of recovery was improved (a positive 8-point difference) or worsened (a negative 8-point difference) \[8, 9\]. A minimum of 49 patients in each group were obtained (3 = 0.05 and 4 = 0.20). Considering 10% possible losses during the study (dropouts), the final sample constituted 110 patients.

Parameters: alpha=0.05, 80% power, MCID 6-10 points, SD 12-22. Formula: n per group = 2 × (Zα/2 + Zβ)\^2 × σ\^2 / δ\^2. Example: For MCID=8, SD=14 → \~49 per group (98 total). Considering \~ 10% added for missing data, final sample is 110 (55 per group). Sample size table attached in appendix. 9. Statistical analysis plan Primary: Compare QoR-15 at 24 h using propensity-score matched analysis (linear mixed model adjusting for surgeon). Secondary: IPTW and regression with baseline covariates. Other outcomes analysed with appropriate models (logistic, Cox, etc.). Missing data handled with complete-case or multiple imputation. Sensitivity analyses include subgroups and alternative propensity approaches. 10. Bias reduction and limitations Collect rich baseline/intraop data; adjust for surgeon clustering; standardize anaesthesia if possible. Limitations: residual confounding, single-centre generalisability. 11. Operational considerations Pilot in first 20-30 patients to confirm SD and feasibility; train staff in CRF and QoR-15 administration; secure de-identified data storage. 12. Ethical considerations Ethics approval required. Informed consent from all participants. Privacy and compliance complaint with data governance. 13. Appendices QoR-15 questionnaire, Case Report Form (CRF), sample size table, Information leaflet, informed consent form attached.