Postoperative serious adverse events in a teaching hospital

In reply: We thank Tracy and Hugh for the issues they raise. The goal of our study was to establish baseline information on the incidence of serious adverse events (SAEs) for use in subsequent intervention studies.1 The data were needed for statistical power calculations. Our inclusion criteria were predefined, as is scientifically orthodox for any study. We chose to study a population of clinical relevance to inpatient medicine. Most simple procedures at our hospital require day admission with no overnight inpatient stay, so these were not relevant to our goals. Others may wish to study different patient populations and are free to do so.

In our opinion, there was no particular bias in our study, just accurate, prospective documentation of events. We used the term "unscheduled surgery" because it is verifiable and objective. An operational definition is necessary; otherwise, judgements about what is a true emergency (like judgements about what is preventable) are very dependent on observer bias. Nonetheless, according to our judgement, only 48 of 426 "unscheduled" operations were true emergencies. We wanted to identify groups that were at particular risk of death, hence the mention of patients over 92 years of age who had had hip surgery. Up to what level of expected postoperative mortality does it remain acceptable to perform major surgery in very elderly patients?

We stand by our opinion that we are dealing with a silent epidemic. It is silent because we could find no previous prospective studies of SAEs for all major operations published (in English) in the medical literature, and there was no systematic plan to tackle them. We use the term epidemic because (in the absence of objective documentation of rates of SAEs in the past) our impression is that this is a growing phenomenon, related to the increased use of major surgery in the elderly. We also consider that only the absence of SAEs would offer no scope for improvement. A rate of SAEs of 16.9% should, logically, offer much scope for improvement. Whether such improvement can be realised remains a matter for future interventional investigations.