In reply
Ladner and colleagues are among the few investigators to examine the degree to which unplanned return to the operating room (OR) can be identified using administrative data. In their assessment of 537 patients, most patients returning to the OR had administrative codes indicating such (sensitivity, 91%); only 4% of patients not returning to the OR had codes indicating reoperation (specificity, 96%). It is uncertain whether claims data from US hospitals would have a similar degree of accuracy.