• B Carvalho, F Mirza, and P Flood.
• Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA.
• Br J Anaesth. 2017 May 1; 118 (5): 762-771.

BackgroundThe study aimed to determine whether a patient's choice for their intrathecal morphine (ITM) dose reflects their opioid requirements and pain after caesarean delivery and if giving women a choice of ITM dose would reduce opioid use and improve pain scores compared with women who did not have a choice.MethodsA total of 120 women undergoing caesarean delivery with spinal anaesthesia were enrolled in this randomized, double-blind study. Patients were randomly assigned to a choice of 100 or 200 μg ITM or no choice. The study involved deception, such that all participants were still randomly assigned 100 or 200 μg ITM regardless of choice. Rescue opioid use over the 48-h study period was the primary outcome measure. Pain at rest and movement and side effect (pruritus, nausea, and vomiting) data were collected 3, 6, 12, 24, 36 and 48 h postoperatively. Data are presented as median [95% confidence interval (CI)].ResultsWomen who requested the larger ITM dose required more supplemental opioid [median 0.8 (95% CI 0.4-1.3)] mg morphine equivalents at each assessment interval; P  < 0.001] and reported more pain with movement [median 1.2 (95% CI 0.5-1.9)] verbal numerical rating score of 0-10 points] than patients who requested the smaller ITM dose ( P  = 0.0008), regardless of the ITM dose given. There was no difference in opioid use whether the patient was offered a perceived choice or not.ConclusionsWomen who were given a choice and chose the larger ITM dose correctly anticipated a greater postoperative opioid requirement and more pain compared with women who chose the smaller dose. Simply being offered a choice did not impact opioid use or pain scores after caesarean delivery.Trial RegistrationClinicalTrials.gov (NCT01425762).© The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

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