We found that postoperative complications were relatively common, occurring in 6.9% of surgical patients in the present study. Each of the postoperative complications studied were associated with substantial increases in total hospital cost and LOS, even after adjusting for type of surgery, urgency of surgery, and preoperative patient comorbid conditions. The relative increase in cost for each of the complications ranged from 41% to 112%. Parallel to the increases seen in costs, complications were associated with similar significant increases in LOS. Pulmonary complications occurred most often and were associated with a substantial increase in hospital cost and LOS. These increases in hospital costs were largely driven by prolonged hospital stay. This conclusion is based on the fact that although most complication types were associated with an increase in hospital cost independent of LOS, the magnitude of the cost increase was considerably lower than in an analysis that does not control for LOS.
These results are consistent with and extend findings from previous investigations of the impact of various perioperative explanatory factors on health care resource utilization in noncardiac surgery.8, 12, 17
Dimick et al.3
reported increases in hospital costs and LOS with several postoperative complications in a study of 1,008 surgical patients. However, because of the small number of events, they were only able to study a limited number of complications and could only adjust for a few comorbid conditions. Our study demonstrated, in a large patient population adjusted for a comprehensive list of comorbid conditions, that complications were associated with substantial costs and prolonged LOS for multiple adverse complications.
The present study has several limitations. The first limitation is that as the costs and LOS results are from a single institution, they may not be representative of other hospitals. However, the complication rates in this study are similar to other reported complication rates from tertiary care centers.8, 18, 19
Second, administrative data might be incomplete and inaccurate in identifying complications. We reduced misclassification of comorbid conditions as complications by using the diagnosis-type indicator13
that identifies each comorbid condition as present at admission. Furthermore, Lawthers et al.16
reported that 73% of surgical complications identified by ICD-9 codes were confirmed against medical record review. A third limitation is that the extreme imbalance of comorbidity profiles between patients with complications and those without might result in incomplete adjustment for potential confounding. While we could not use multivariable matched analyses proposed by some authors20
because of the low matching rate, we have attempted to reduce confounding by using a comprehensive list of comorbid conditions.11, 12
The fourth limitation is that patients in this study underwent surgery between 1996 and 1998 and since that time, direct and indirect hospital costs may have increased. Also, costs in the single payer Canadian system are generally lower than quoted costs or charges from the American system. However, the overall conclusion that postoperative complications are independently associated with a significant increase in cost and LOS remains true, and is likely to apply to more recent Canadian data and to American data.
A final caveat is that we studied complications regardless of the occurrence of death. The relationship between death and costs/LOS is complicated, as death occurring early or late during the hospital admission would have differing effects on cost and LOS. In this study, the effect of death on resource use (cost and LOS) was, on average, modest, but this represents an averaged summary of effects that range anywhere from huge decreases in resource use (for early deaths) and huge increases in resource use (for later deaths).
In conclusion, patients with postoperative complications consume considerably more health care resources. Initiatives that target prevention of these events, even if costly to implement, would significantly improve quality of care and patient safety, with potential to also decrease the overall costs of care.