Clinical Prediction Rules

The objective of clinical prediction rules (decision rules) is to reduce the uncertainty inherent in medical practice by defining how to use clinical findings to make predictions.¹A decade ago, we assessed the quality of clinical prediction rules published from 1981 through 1984 in four major medical journals. Since then the availability of powerful computers and easy-to-use software programs has increased dramatically. This environment has stimulated the production of clinical prediction rules. During the last calendar year,JAMApublished more clinical prediction rules than it did during the 4-year period covered by our original review. In this issue ofTHE JOURNAL, Stiell et al²demonstrate a method for targeting use of knee radiographs in acute knee injuries by applying five clinical predictors of knee fractures. When the prevalence of fracture is 6%, the probability of a clinically important fracture is estimated to be less than 0.4%, if these