To the Editor The article published by Khor et al1 represents a well-intentioned effort to predict individual outcomes of lumbar fusion, which has grown in popularity and cost to health care systems despite major unanswered questions about its proper role in managing degenerative lumbosacral spine disease. We have questions about the methods and the reliability of the predictive model presented by Khor et al1 and about its readiness for public release as a web app.