In addition to 30-day mortality, we examined failure-to-rescue (deaths within 30 days of admission among patients who experienced complications). Complications were identified by scanning discharge abstracts for International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes in the secondary diagnosis and procedure fields that were suggestive of 39 different clinical events. Distinguishing complications from previously existing comorbidities involved the use of rules developed by expert consensus and previous empirical work, as well as examination of discharge records for each patient's hospitalizations 90 days before the surgery of interest for overlap in secondary diagnosis codes. Examples of complications included aspiration pneumonia and hypotension/shock. Patients who died postoperatively were assumed to have developed a complication even if no complication codes were identified in their discharge abstracts.