The purpose of this article is to review the current state of outcome measurement in spine surgery, with an emphasis on patient-reported outcome measures (PROMs). The commonly used generic and disease-specific outcome measures used in spinal surgery and research will be discussed. The authors will introduce the concepts of response shift and appraisal processes, which may affect the face validity of PROMs, as well as their interpretation over time. It is not uncommon for there to be a discrepancy between the observed and expected outcome, which is not wholly explainable by objective measures. Current work on understanding how appraisal affects outcome measurement will be discussed, and future directions will be suggested to facilitate the continued evolution of PROMs.There has been an evolution in the way clinicians measure outcomes following spinal surgery. In moving from purely physical, objective measures to a growing emphasis on the patient's perspective, spine surgery outcomes are better able to integrate the impact at multiple levels of relevant change. Appraisal concepts and methods are gaining traction as ways to understand the cognitive processes underlying PROMs over time. Measurement of appraisal is a valuable adjunct to the current spine outcome tools.
Keywords: ICF = International Classification of Functioning, Disability, and Health; IRT = item response theory; ODI = Oswestry Disability Index; PROM = patient-reported outcome measure; PROMIS = Patient-Reported Outcomes Measurement Information System; QOL = quality of life; QOLAP = QOL Appraisal Profile; VAS = visual analog scale; appraisal; interpretation; minimal important difference; patient-reported outcomes; response shift; review.