The objective is to measure the adjusted association between preoperative anemia and total hospital costs. We hypothesize that patients with anemia before surgery will have higher hospitalization costs than people without anemia.

This study will examine the association between preoperative anemia (hematocrit less than 0.39; low blood counts) and hospital total costs from elective colorectal surgery. Total costs will be defined as the combination of direct and indirect costs ascertained using standardized patient-level costing algorithms (i.e. the standard way that hospital measure their costs). Adjustment will be made for factors that are likely to influence both the presence of anemia and costs of care.

Inclusion Criteria:

• Elective hospital admission
• having colorectal surgery

Exclusion Criteria:

• not enrolled in national surgical quality improvement program data collection

All adults having elective colorectal surgery with national surgical quality improvement program data available

AEs were not collected

AEs were not expected or collected.

Findings may not be generalizable to other jurisdictions with different hospital funding models and findings provide only an association between anemia and costs. There is risk of confounding bias due to unmeasured variables that might influence the presence of anemia or the accumulation of costs. The lack of integration of transfusion costs in our healthcare system required us to estimate the added cost of transfusions, and we were also unable to account for physician remuneration costs.