Study finds preoperative donors far more likely to receive transfusions

A study of patients who provided autologous blood donation prior to surgery for adolescent idiopathic scoliosis (AIS) found that they were more likely to receive transfusions than patients who did not donate blood. In addition, researchers found that more than half of the autologous blood donation was not used. As a result, the investigators no longer recommend preoperative autologous blood donation (PABD) for their AIS patients.

Presenting on behalf of his coauthors at the 2011 annual meeting of the Scoliosis Research Society, Lukas P. Zebala, MD, of Washington University in St. Louis, noted the well-recognized advantages of PABD, in particular the reduced risk of virus and antibody transmission. But although PABD is seen as a low-risk process, it does have disadvantages, including patient dissatisfaction (especially among children who might dislike the collection procedure), overcollection of blood, a reduction in the patient’s preoperative hematocrit, high cost, and unused blood.

Minimizing blood loss and perioperative blood transfusions is important, Dr. Zebala noted. Factors that can limit blood loss include proper patient positioning, surgical technique, and pharmacologic measures.

Factors in transfusion
The study involved 88 patients with AIS at a single institution (two hospitals). Parents and patients decided whether to donate blood preoperatively; 32 were in the PABD group and 54 were in the non-PABD group. “Patients did not want to be randomized,” said Dr. Zebala. “For young children and adolescents, giving blood can be a scary thing.”

The surgical procedure was primary single stage, posterior, anterior, or combined instrumentation or fusion for AIS, performed by one of two surgeons. The groups had similar demographics, with similar type and extent of deformity.

Preoperative hematocrit measurement found that patients in the PABD group had lower levels than those in the non-PABD group (38.2 versus 39.8; P = 0.04). Hematocrit levels in both groups decreased slightly after surgery.

During surgery, the PABD patients were considerably more likely to receive a transfusion; 18 of 32 patients (56 percent) received a transfusion, compared with 8 of 54 non-PABD patients (P = 0.004). Among donors, 81 percent received either an intra- or postoperative transfusion, compared with 41 percent of nondonors.

The researchers were able to match 28 pairs (56 patients) from the two groups by preoperative hematocrit level. Among these patients, 14 received transfusions—12 (86 percent) from the PABD group and 2 (14 percent) from the non-PABD group (P = 0.008). Analysis of postoperative transfusions in the matched pairs yielded similar results. Researchers also performed additional analyses that showed preoperative donation was an overwhelming factor in predicting transfusion.

A total of 58 units of blood had been donated by the PABD group; 36 units (62 percent) were “wasted”—not given back to patients in transfusions. In 23 of these patients (72 percent), a minimum of one unit of blood was not given back. In patients who had given 2 or 3 units of blood, about half did not get any blood back, and researchers found a significant correlation (P < 0.0001) between the number of autologous units given and the number of units not transfused back.

Among the strengths of the study, Dr. Zebala said, were its prospective nature, its setting in just one medical center, and the large amount of data collected. Weaknesses included the inability to effectively randomize patients, lack of a constant transfusion trigger, and lack of standardized timing of preoperative hematorcrit measurement.

In view of the higher transfusion rates for donor patients, the wasting of 62 percent of the donated blood, and the greatly increased probability for transfusion among donors, Dr. Zebala concluded that preoperative donation cannot be supported.

Not totally benign
Several audience members indicated reservations about the authors’ concluding recommendation against routine autologous donation. Dr. Zebala said the strong tendency to give blood back to the donor detected in this study should give pause.

“The conclusion was not that the lower preoperative hematocrit triggered transfusions,” he said. “Because the patients have donated blood and it is available, the surgeon’s response to a low hematocrit level is to transfuse. In a nondonated setting, that wouldn’t necessarily be the first response. We have to consider that even autologous donated blood is not a benign issue. Transfusion reactions have been reported.”

Resource allocation and cost are also considerations, he said. “We were surprised by how much of the blood that was donated was never transfused. It seemed like a waste of a resource, which other studies have also shown. Donated blood is a resource-intensive process. If you’re going to obtain preoperative donations but you’re not going to use them 60 percent of the time, does it really make sense from an economic standpoint to ask for them?”

Finally, he noted, “Patients don’t like to donate. We couldn’t randomize donation. We are not the only ones to conclude that preoperative autologous blood donation may not be of benefit.”

Co-authors of the study are Lawrence G. Lenke, MD; Keith H. Bridwell, MD; Jacob M. Buchow-ski, MD; and Brenda Sides, MA.

Disclosure information: Dr. Zebala—Pioneer Surgical Technology; Dr. Lenke—Axial Biotech, DePuy, Medtronic, Quality Medical Publishing; Dr. Bridwell—NIH, DePuy; Dr. Buchowski—Stryker, CoreLink. Ms. Sides reported no conflicts.

Terry Stanton is senior science writer at AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

• Autologous blood donation provides a safe blood source but has disadvantages, including lowered hematocrit, extra cost, and waste.
• In this study, patients who donated blood before undergoing surgery to correct a spine deformity were significantly more likely to receive transfusions during and after surgery than those who did not.
• Sixty-two percent of the blood collected from patients was not returned to them in transfusion.
• Based on these results, the investigators do not recommend routine use of preoperative autologous blood donation.