A model for predicting transfusion requirements in head and neck surgery.

Introduction. Although allogeneic blood transfusions have allowed surgeons increased latitude in resecting advanced cancers, they can cause significant morbidity or even death in rare instances. Potential side effects may include transmission of infection and immunosuppression leading to an increased risk of cancer recurrence. Because patients have become more reluctant to receive transfusions, they frequently request preoperative autologous blood donation (PABD). In practice, however, only 50% or less of the donated blood is ultimately transfused while the remainder is discarded. Purpose. The purpose of this study was to develop a transfusion prediction and risk assessment (TPRA) model for predicting the need for perioperative blood transfusions in patients undergoing major head and neck oncologic surgical procedures. By knowing the probability for blood transfusion, the physician and patient can make an educated decision regarding the need for PABD. Patients and Methods. Over a 4-year period, 436 patients underwent major head and neck surgical procedures for neoplasms of the upper aerodigestive tract, the thyroid gland, and the salivary glands. Data obtained prospectively on each patient included age and gender, the TNM stage, primary disease site, type of prior treatment, estimated intraoperative blood loss, duration of surgery, transfusion requirements, preoperative and postoperative hemoglobin and hematocrit levels, type of procedure and method of reconstruction. These variables were examined singly and in combination both for descriptive purposes and to evaluate their interrelationships. In order to develop the TPRA model, only the 12 variables available prior to the surgical procedure were examined. Variables associated with transfusion need were evaluated further in a multivariate analysis. The logistic regression model allowed a linear expression of patient characteristics to be related to a function of the probability of transfusion need. Analyses of association between categorical variables and transfusion status were based on chi-squared, Fisher's Exact, and Mann-Whitney U tests. Results. Overall, 51 (11.7%) patients required blood transfusions. The median number of units transfused was 2.0 (range, 1 to 13 U). Univariate analysis demonstrated a higher probability for blood replacement in patients with oropharyngeal or hypopharyngeal primary tumor sites, a preoperative hemoglobin level below normal, prior chemotherapy, composite resection, flap reconstruction, between 50 and 59 years of age, and T3 or T4 tumor stage. Logistic regression analysis demonstrated that the need for flap reconstruction, a preoperative hemoglobin below the normal level, and T3 or T4 primary stage were the three factors most significantly associated with the need for transfusion (P<.03). Based on eight combinations of these three variables, transfusion risk predictions were obtained. The TPRA model predicted that patients with a normal hemoglobin level who did not require flap reconstruction and did not have either a T3 or T4 primary stage tumor had the lowest probability (.02) for requiring blood transfusion. Patients at highest risk (.65) were those with less than a normal hemoglobin level, who required flap reconstruction, and had T3 or T4 primary tumor stage. Based on the TPRA model, an algorithm was developed which could serve as a guideline for preoperative transfusion planning. Conclusion. By using the TPRA model to change guidelines for preoperative transfusion planning, costs can theoretically be reduced by 50% without significantly increasing the risk of exposing patients to allogeneic blood transfusion. If the TPRA model proves accurate in a follow-up study to test its validity, it may have clinical utility for aiding the surgeon in more cost-effective transfusion planning.