Clinically Important Difference in Quality of Recovery Scores

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Perioperative interventions that improve the quality of recovery after anesthesia and surgery are needed. Fortunately, serious complications are rare, but minor, even transient complications, discomfort, and psychological distress have a significant effect on a patient’s overall quality of recovery. A narrow focus on any single aspect of a patient’s postoperative recovery, for example, wound pain or vomiting, can lead to tunnel vision, a type of attentional bias in which other sources of patient discomfort or impairment, such as dyspnea, confusion, or thirst, are not considered. Some treatments may improve one symptom, for example, pain, but create others, such as nausea, excessive sedation, or delirium.Clinical trials are required to nominate study end points that may or may not truly represent the interests of the patient, and yet, the sample size estimation and resultant statistical power are mostly based on the nominated primary end point. Trials are rarely powered to detect treatment side effects or evaluate overall cost-effectiveness, despite these aspects often being of more importance to patients and society. Composite end points and/or health status scales can be used to measure a broader range of outcome events and typically provide more statistical power so that useful treatment effects can be identified. Quality of recovery scales offer particular value in this regard.1,2Overall quality of recovery after surgery and anesthesia should be defined from the patient’s perspective.3,4 An extensive literature review, clinician and patient surveys, and psychometric development and validation led to a series of quality-of-recovery scores to measure a patient’s global health status after surgery,4–9 with the most extensively validated being the 40-item quality-of-recovery scale (the QoR-40).10 Other instruments have also been developed.11,12The QoR-40 has 5 dimensions of recovery: (1) emotional state, (2) physical comfort, (3) psychological support, (4) physical independence, and (5) pain control, with each item rated on a 5-point Likert scale. Global QoR-40 scores range from 40 to 200, representing, respectively, very poor to excellent quality of recovery. The QoR-40 is a simple, valid, reliable, and responsive instrument.5,10In this issue of Anesthesia & Analgesia, Alves et al.13 report on a clinical trial evaluating the outcome benefits of duloxetine, an antidepressant frequently used to treat fibromyalgia and other chronic pain conditions, in patients undergoing abdominal hysterectomy with spinal anesthesia. The primary outcome metric was the QoR-40 score at 24 hours. They found that duloxetine given before and at 24 hours after surgery increased the median (95% confidence interval) QoR-40 score by 9 (95% confidence interval, 4–20) points, which was statistically significant at P < 0.001. The actual median QoR-40 scores for the duloxetine and control groups at 24 hours after surgery were 196 and 187, respectively. This might seem impressive, but the key question readers will want to answer is whether this change in scores is clinically important? That is, does a 9-point change in QoR-40 scores mean that patients actually recover better overall? Of relevance, the authors also identified a reduction in pain scores and opioid consumption at 24 hours after surgery in those receiving duloxetine compared with control.Clinicians sometimes need to be reminded that a statistically significant change in a health status scale (or pain) score may not represent a clinically important change in health status (or pain). There is a subtle but important difference.14,15To help interpret the trial by Alves et al.,13 we know from previous work that patients undergoing minor, intermediate, and major surgery have mean ± SD postoperative QoR-40 scores of 178 ± 17, 173 ± 17, and 166 ± 15, respectively.

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