To The Editor:
The article by Ricci et al., "Is After-Hours Orthopaedic Surgery Associated with Adverse Outcomes? A Prospective Comparative Study" (2009;91:2067-72), was incorrectly designated as a therapeutic Level-I study. According to the JBJS guidelines, a therapeutic Level-I study is a randomized controlled trial, and this study was not.
The study perhaps could be considered to be under the category "prognostic studies—investigating the effect of a patient characteristic on the outcome of disease." (In this case, the "patient characteristic" is the time of the operation.) In the JBJS guidelines, a prognostic study can be considered Level I if it was "high-quality." Of course, the height of quality is a subjective judgment, but we question whether this study is of sufficiently high quality to be deemed Level I. For one thing, the two groups were patently dissimilar beyond the variable in question; in addition, the sample size was inadequately powered.