A MODEL FOR PREDICTING TRANSFUSION REQUIREMENTS IN HEAD AND NECK-SURGERY

Introduction. Although allogeneic blood transfusions have allowed surg eons 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 le ading to an increased risk of cancer recurrence. Because patients have become more reluctant to receive transfusions, they frequently reques t 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 p redicting the need for perioperative blood transfusions in patients un dergoing 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 Me thods. Over a 4-year period, 436 patients underwent major head and nec k surgical procedures for neoplasms of the upper aerodigestive tract, the thyroid gland, and the salivary glands. Data obtained prospectivel y on each patient included age and gender, the TNM stage, primary dise ase site, type of prior treatment, estimated intraoperative blood loss , duration of surgery, transfusion requirements, preoperative and post operative hemoglobin and hematocrit levels, type of procedure and meth od of reconstruction. These variables were examined singly and in comb ination both for descriptive purposes and to evaluate their interrelat ionships. In order to develop the TPRA model, only the 12 variables av ailable prior to the surgical procedure were examined. Variables assoc iated with transfusion need were evaluated further in a multivariate a nalysis. 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 vari ables and transfusion status were based on chi-squared, Fisher's Exact , and Mann-Whitney U tests. Results. Overall, 51 (11.7%) patients requ ired blood transfusions. The median number of units transfused was 2.0 (range, 1 to 13 U). Univariate analysis demonstrated a higher probabi lity for blood replacement in patients with oropharyngeal or hypophary ngeal primary tumor sites, a preoperative hemoglobin level below norma l, prior chemotherapy, composite resection, flap reconstruction, betwe en 50 and 59 years of age, and T3 or T4 tumor stage. Logistic regressi on analysis demonstrated that the need for flap reconstruction, a preo perative hemoglobin below the normal level, and T3 or T4 primary stage were the three factors most significantly associated with the need fo r transfusion (P<.03). Based on eight combinations of these three vari ables, transfusion risk predictions were obtained. The TPRA model pred icted 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 he moglobin level, who required flap reconstruction, and had T3 or T4 pri mary 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 preoper ative transfusion planning, costs can theoretically be reduced by 50% without significantly increasing the risk of exposing patients to allo geneic blood transfusion. If the TPRA model proves accurate in a follo w-up study to test its validity, it may have clinical utility for aidi ng the surgeon in more cost-effective transfusion planning.