From the 1Department of Orthopaedics at the Hospital for Special Surgery in New York City, New York, and 2Weill Cornell Medical College in New York City, New York.
OUTCOME MEASURES
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Minimal Clinically Important Difference in Spine Surgery Are We Using the Right Thresholds?
Sereen Halayqeh, MD1
P a t i e n t-r e p or t e d ou t c om e m e a s u r e s (PROMs) now sit near the center of spine outcomes research because the question that matters after surger y is not simply whether radiographs improved, whether a fusion healed, or whether a p value crossed 0.05. The more important question is whether the patient’s pain, function, and quality of life changed in a way that matters to the person living with the result. That is the gap minimal clinically important difference (MCID) was designed to address. Jaeschke et al originally framed the MCID as the smallest change in health status that patients themselves would identify as important.1 In spine surgery, that concept is useful because statistically significant improvement can still be clinically trivial, while a patient-centered improvement may be obscured if investigators focus only on mean score changes. This framework fits naturally into spine surger y because the field relies heavily on PROMs such as disability scales, pain scores, and general health-status instrument s. T he s e mea su re s help c apt u re what imaging and technical endpoints often cannot: whether patients can walk farther, sit longer, sleep better, return to work, or function w ith less pain. MCID
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gives those numerical changes a clinical reference point by asking whether the amount of improvement was meaningful, not merely measurable. However, MCID is not a uniMichael Greenberg, BA1 versal constant, and its interpretation depends on both the clinical and methodological contex t. T h is tension mot ivates the central question of this review: are current MCID thresholds appropriate for all Sravisht Iyer, MD1,2 spine surgery patients, or are they often treated with more certainty than the evidence justifies?
What Is MCID? MCID refers to the smallest change in an outcome score that patients perceive as important enough to matter in real life or to justify a change in management. 2 In spine surgery, it is usually applied to PROMs such as the Oswestr y Disabilit y Index (ODI), Neck Disability Index (NDI), visual analog or numeric pain scales, SRS-22, EQ-5D, and Patient-Reported Outcomes Measurement Information System (PROMIS) measures. 2–4 These tools measure related but distinct domains, including disability, pain inten-
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