How Much Better Is Good Enough? Patient reported Outcomes, Minimal Clinically Important Differences, and Patient Acceptable Symptom States in Perioperative Research.
<zdoi;10.1097/ALN.0000000000001159> Anesthesiology, V 125 No 1 7 July 2016 M ortality after surgery is increasingly rare in developed countries.1 Nonetheless, many opportunities exist to improve perioperative care. For example, surgical patients still need postoperative comfort that involves minimization of postoperative pain, prevention of nausea, and facilitation of early mobilization. Many patients continue to experience major nonfatal complications that result in long term disability and poorer quality of life. Given this context, the patientreported outcome (Pro) is likely to take on an increasingly important role in perioperative research. For example, several available scales can now integrate and quantify the multiple dimensions constituting quality of recovery (Qor) after surgery.2,3 Disability and health related quality of life scales can assess the impact of postoperative morbidity on patients' ability to return to normal function and quality of life.4,5 While Pros that have undergone rigorous psychometric evaluation can help better assess patients' perioperative experience, they also introduce new challenges. a critical issue is determining the minimal clinically important difference (MCiD) or the smallest difference in Pro scores that "patients perceive as beneficial."6 taking the example of the commonly used numeric rating scale of pain intensity, what reduction in pain scores represents a meaningful improvement in postoperative pain for a patient? This information can help physicians assess whether treatment effects in a randomized trial are clinically relevant and help researchers more accurately estimate sample sizes for any study that includes a Pro.7 in this issue of aNesthesioloGy, Myles et al.8 present a highquality prospective cohort study that determined the MCiD of three postoperative Qor scales, namely the Qor score, Qor 15, and Qor 40. The investigators recruited 204 patients undergoing a broad range of surgical procedures at three australian hospitals. The participants completed the three Qor scales at several postoperative time points, with 199 individuals undergoing at least 2 postoperative interviews. Based on several different analyses, the investigators found the MCiD to be 0.9 for the Qor score, 8.0 for the Qor 15, and 6.3 for the Qor 40. This wellconducted study is likely to form the methodologic foundation for many future studies evaluating Qor in surgical patients. Given its importance, and the paucity of similar studies in the anesthesiology literature, we will focus the remainder of this editorial on typical methods for estimating the MCiD and future directions for such research in the perioperative arena.
Anesthesiology