Impact of autologous blood reinfusion on blood conservation and economic efficiency during posterior spinal fusion for scoliosis in school-age children

doi:10.21203/rs.3.rs-1524609/v1

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Impact of autologous blood reinfusion on blood conservation and economic efficiency during posterior spinal fusion for scoliosis in school-age children

https://doi.org/10.21203/rs.3.rs-1524609/v1

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Background: The effectiveness and affordability of autologous blood reinfusion during posterior spinal fusion for scoliosis in school-age children are under debate. The purpose of this study is to investigate whether autologous blood reinfusion during posterior spinal fusion for scoliosis in school-age children can save blood usage and medical costs.

Methods: Data of 194 consecutive patients aged 7-12 years from January 1, 2010, to June 31, 2020, were collected from the 306th Hospital of the People's Liberation Army. The patients were divided into a control group and an autologous blood reinfusion group based on whether a Cell Saver 5 Autologous Blood Recovery System was used. After propensity score matching using the caliper method, the data of 72 patients were matched successfully. Their perioperative indicators were accessed, and the blood transfusion-related costs were evaluated.

Results: Compared with the control group, the volume of allogeneic red blood cells (RBCs) transfused in the cell saver group was lower during the surgery (P = 0.021), but there was no significant difference during the postoperative and the entire perioperative periods (P = 0.600, P = 0.051); the volume of allogeneic plasma infused was lower during the surgery and the entire perioperative period (P = 0.011, P = 0.018), but there was no significant difference after surgery (P = 0.276). In addition, the total blood transfusion costs for the autologous blood reinfusion group were slightly higher, but the difference was not significant (P = 0.331).

Conclusions: During posterior spinal fusion for scoliosis in school-age children, autologous blood reinfusion can reduce allogeneic RBC and plasma transfusions during surgery but cannot reduce the need for allogeneic RBCs during the entire perioperative period and is not cost effective.

autologous blood reinfusion technique

scoliosis

blood transfusion

school-age children

economic efficacy

The incidence of scoliosis in elementary school students in China is approximately 1.02% [1]. Posterior spinal internal fixation is an important treatment option. Intraoperative and postoperative blood loss during this major surgery is substantial, often requiring allogeneic blood transfusion. Although modern blood transfusion techniques are relatively safe, complications such as allergic reactions and transmitted diseases cannot be completely avoided[2]. Therefore, techniques to reduce allogeneic blood transfusions have been explored.

Intraoperative autologous blood reinfusion has been applied in posterior spinal internal fixation for more than 20 years, and its application has been reported in different years and countries. However, its effectiveness and affordability are under debate, and the study populations have been mostly adolescent children to adults [3–7]. Given the lack of published studies on this type of research in school-age children, this study was designed to investigate the impact of autologous blood reinfusion during posterior spinal fusion for scoliosis in school-age children.

This study was approved by the Institutional Review Board (IRB) of the No. 306 Hospital of the People's Liberation Army and had a retrospective clinical design. The personal information of all patients was anonymized; therefore, the requirement for written informed consent was waived by the IRB/Ethics Committee of the No. 306 Hospital.

Using the electronic medical record system of the 306th Hospital of the People's Liberation Army (Beijing Medical System), we obtained the data of consecutive patients who underwent pedicle screw placement for posterior spinal fusion for scoliosis between January 1, 2010, and June 31, 2020. The collected indicators included sex, age, body weight, preoperative hemoglobin (Hb), preoperative Cobb angle, duration of operation (min), intraoperative blood loss, number of fused segments, osteotomy, Hb before discharge, volumes of intraoperative and postoperative allogeneic red blood cell (RBC) and plasma transfusions, volumes of intraoperative crystalloid and colloid infusions, and intraoperative urine output. The patients were divided into a control group and an autologous blood reinfusion group based on whether a Cell Saver 5 Autologous Blood Recovery System (Haemonetics Corporation, MA, USA) was used. The major indicators of evaluation included volumes of allogeneic RBC and plasma infusions during the intraoperative, postoperative and the entire perioperative periods, the economic efficacy was also assessed.

In the 306th Hospital of the People's Liberation Army, surgeons recommend the patients with sever scoliosis to use a cell saver system to avoid the possible substantial intraoperative blood loss during the surgery. If a patient is younger than 7 years or weighs less than 20 kg, an intraoperative cell saver system won’t be considered. Therefore, the inclusion criteria for this study were congenital and idiopathic scoliosis patients age 7–12 years and weighing ≥ 20 kg who underwent initial posterior spinal fusion for scoliosis. Patients with a history of coagulation disorders, neuromuscular scoliosis or severe cardiopulmonary dysfunction and patients who received erythropoietin and other related drugs, underwent preoperative autologous blood collection, intraoperative administration of antifibrinolytic or hemostatic drugs such as aminomethylbenzoic acid, and intraoperative hemodilution were excluded from the study.

During the operation, the depth of anesthesia was regulated, and vasoactive drugs were applied to control hypotension and maintain a mean arterial pressure of 50–60 mmHg. The total volume of blood loss during the perioperative period was calculated based on the volume of intraoperative blood loss and postoperative incisional drainage. Based on the Beijing Clinical Blood Management Guidelines, blood transfusion indications for surgical patients during the intraoperative are either Hb < 7.0 g/dl, or Hb < 8.0 g/dl combined with symptoms such as an elevated heart rate, low blood pressure and so on. The indications for postoperative blood transfusion are the same.

According to Beijing’s medical cost standards, the price of washed allogeneic RBCs is $69.87/U, and the price of fresh frozen plasma is $12.45/200ml, based on the exchange rate of USD to RMB 7.07 as of July 1, 2020 (both from 200 ml of whole blood). The cost of cell saver usage is $ 268.74. Based on those values, the total blood transfusion cost for each patient was calculated.

Statistical analysis

In this study, the baseline information of the children in the two groups, i.e., sex, age, weight, preoperative Hb, preoperative Cobb angle, duration of operation (min), volume of intraoperative blood loss, number of fused segments, and osteotomy or not, were not fully consistent. Therefore, propensity score matching was used to reduce selectivity bias. The specific method involved including each baseline indicator in a logistic regression model [8] to calculate a propensity score for each patient. Based on the closest propensity score, 1:1 pairing of patients in the control group and the study group, i.e., neighborhood matching, was performed, and the caliper range was set as 0.2. Continuous variables are expressed as the mean ± sem, and the independent sample t test was used for comparison. The chi-squared test was used for comparing categorical variables. P < 0.05 indicated that a difference was statistically significant. Propensity score matching and statistical analyses were performed using SPSS 19.0 (IBM corporation, Chicago, IL, USA).

Excluding patients with incomplete information, 194 children were initially selected. The non-study baseline indicators in the original data were not completely balanced; the difference between intraoperative blood loss and receiving an osteotomy or not was highly significant (P = 0.005, P = 0.010), and there was also a significant difference in age and preoperative Hb level (P = 0.030, P = 0.033). After propensity score matching using the caliper method, 36 patients in the control group were matched with patients in the cell saver group, and the remaining patients were excluded due to unsuccessful matching. The matching results for the two groups were good, and the aforementioned baseline indicators were all consistent. The results are shown in Table 1.

Table 1

Distribution of baseline indicators of patients before and after propensity score matching
	Overall Cohort			Propensity-Matched Cohort
	Control (n = 153)	Cell saver (n = 41)	P	Control (n = 36)	Cell saver (n = 36)	P
Gender (Male/Female)	49/104	13/28	0.969	9/27	11/25	0.793
Age (yr)	10.93 ± 0.10	10.41 ± 0.26	0.030	10.83 ± 0.23	10.72 ± 0.25	0.744
Body weight (kg)	35.40 ± 0.81	32.80 ± 1.04	0.120	34.18 ± 1.48	33.69 ± 1.08	0.791
Pre-op hemoglobin (g/dl)	124.94 ± 0.90	129.19 ± 1.83	0.033	127.34 ± 1.79	127.02 ± 1.73	0.895
Pre-op Cobb angle of major curvature(°)	78.72 ± 2.47	77.34 ± 3.89	0.791	70.58 ± 5.27	75.53 ± 4.00	0.455
Duration of the operation (min)	257.94 ± 7.20	275.00 ± 12.16	0.265	274.86 ± 15.94	264.86 ± 12.83	0.627
Intraoperative EBL (ml)	1043.20 ± 74.18	1504.88 ± 151.73	0.005	1409.72 ± 166.44	1344.44 ± 146.02	0.769
Number of levels fused	5.03 ± 0.20	5.49 ± 0.28	0.272	6.22 ± 0.41	5.61 ± 0.30	0.237
Osteotomy(yes/no)	103/50	36/5	0.010	26/10	30/6	0.396

Compared with that in the control group, the volume of allogeneic RBC transfusion in the cell saver group was lower during the surgery (P = 0.021), but there was no significant difference during the postoperative and the entire perioperative periods (P = 0.600, P = 0.051); the volume of allogeneic plasma infusion was lower during surgery and the entire perioperative period (P = 0.011, P = 0.018), but there was no significant difference after surgery. The results are shown in Table 2.

Table 2

Blood transfusion conditions and other perioperative research indicators
	Control(n = 36)	Cell saver(n = 36)	P
Allogeneic RBC (units)
Intraoperative(units)	5.89 ± 0.69	3.86 ± 0.51	0.021
Postoperative (units)	2.67 ± 0.44	2.33 ± 0.46	0.600
Total perioperative (units)	8.56 ± 0.94	6.19 ± 0.72	0.051
FFP transfusion (ml)
Intraoperative (ml)	494.44 ± 67.37	283.33 ± 44.63	0.011
Postoperative (ml)	200.00 ± 39.04	138.89 ± 39.70	0.276
Total perioperative (ml)	694.44 ± 88.55	422.22 ± 69.82	0.018
Other perioperative paraeters
Crystalloids (ml)	1403.03 ± 114.44	1380.56 ± 111.19	0.888
Colloids (ml)	1132.35 ± 82.60	960.00 ± 89.37	0.162
Reinfused amount of RBC (ml)		416.48 ± 48.92
Intraoperative urine volume(ml)	798.48 ± 87.05	822.41 ± 85.69	0.846
Postoperative hospital stay (days)	15.67 ± 1.13	16.14 ± 0.98	0.753
Postoperative drainage (ml)	757.50 ± 133.11	576.67 ± 85.91	0.277
Total perioperative amount of EBL (ml)	1943.06 ± 207.96	1811.11 ± 171.71	0.626
Postoperative Cobb angle of major curvature (°)	32.22 ± 4.11	38.96 ± 2.94	0.178
Discharge hemoglobin (g/dl)	116.56 ± 12.76	102.17 ± 3.28	0.350

The intraoperative autologous blood reinfusion volume in the cell saver group was 416.48 ± 48.92 ml. Compared with those in the control group. There were no significant differences in intraoperative crystalloid infusion (P = 0.888), colloid infusion (P = 0.162), intraoperative urine output (P = 0.846), postoperative hospital stay (P = 0.753), postoperative incisional drainage (P = 0.277), total perioperative blood loss (P = 0.626), postoperative Cobb angle (P = 0.178), and Hb at discharge (P = 0.350) between two groups. The results are shown in Table 2.

Combining the costs of intraoperative autologous blood reinfusion, allogeneic RBCs and plasma during the perioperative period, the cost was slightly higher in the cell saver group than in control group (¥ 727.83 ± 64.08 vs 641.01 ± 70.19 ), but no significant difference was identified (P = 0.331).

Among orthopedic surgeries, posterior spinal internal fixation and fusion for scoliosis causes the largest amount of trauma. It often requires the transfusion of allogeneic RMCs and plasma to correct anemia[9]. Although the safety of blood products has greatly improved in recent years, blood transfusion-related complications still cannot be completely avoided [2, 10, 11]. More importantly, delays of surgeries due to inadequate blood supply has been an issue noted by Chinese doctors for many years.

As one of the important blood conservation methods, intraoperative autologous blood reinfusion has been widely used in orthopedic spinal surgery for more than 20 years, but its effectiveness and economic efficacy related to conserving blood is still controversial. A study by Owens et al[12] with patients at an average age of 57.2 years showed that a cell saver system could not reduce intraoperative and postoperative blood usage during posterior spinal fusion surgery. A study by Kelly et al [13] demonstrated that a cell saver system had poor economic efficacy after studying 508 adult patients who underwent posterior spinal fusion. A study by Canan et al[14] showed that the use of a cell saver system in single-segment lumbar decompression and fusion surgery for patients older than 18 years cannot reduce the need for allogeneic blood and is not economically efficient. The work by Akgul et al [5] showed poor results for the application of a cell saver system for scoliosis patients who were, 17 to 18 years old on average. Weiss et al[7] and Michelet et al[15] studied the application of cell saver systems in posterior spinal fusion for scoliosis in patients who, on average, were 13–14 years old and in 147 patients who were 15 ± 3 years old, respectively, and the results suggested poor effects of cell saver systems. However, other studies reported that cell saver system can reduce blood usage and is cost effective. A study with patients who, were approximately 15–16 years old showed that among patients undergoing posterior spinal fusion for scoliosis, the allogeneic blood transfusion rate could be reduced from 32.7–14.5% and the blood transfusion volume can be decreased from 0.58 U to 0.21 U for each patient through the application of a cell saver system; furthermore, the number of fused segments, preoperative low Hb and the use of a cell saver system predicted the requirement for a blood transfusion [16]. A study with patients who were approximately 14 years old showed that a cell saver system could reduce blood usage in patients with pediatric idiopathic scoliosis, especially when the operation time was longer than 6 h and the blood loss volume was > 30% of the total blood volume [3].

A meta-analysis published by Cheriyan et al[17] included 15 retrospective and three prospective studies, including a total of 2815 patients undergoing posterior spinal fusion, including patients with scoliosis. The conclusion was that cell saver systems can reduce intraoperative allogeneic RBC demand but cannot reduce the total volume of postoperative and perioperative blood transfusions and the proportion of patients requiring blood transfusion, but the economic efficiency of cell saver systems was difficult to evaluate. A systematic review of the efficacy of autologous blood reinfusions during surgery for scoliosis, which was published by Stone et al[18] in 2017, included seven studies with patients who, on average, were 10–19 years old, and the conclusion was that cell saver systems reduced the blood usage. However, this paper only included one randomized controlled trial (RCT); the other six studies were retrospective, and the final level of evidence was only level 4.

Previously published studies on the application of intraoperative autologous blood reinfusion during the surgical treatment of scoliosis have mostly included adolescent patients who were 13–18 years old [3, 5, 7, 16]. To date, there have been no reports on school-age children between 7–12 years old. The purpose of this study was to investigate whether the application of intraoperative autologous blood reinfusion in school-age children can reduce the need for allogeneic RBCs and plasma and blood transfusion costs. Although this was a retrospective study, post hoc randomization of the control group and the cell saver group was conducted using propensity score matching with matched baseline indicators. Therefore, the results reported in study have increased reliability relative to those in previous studies with inconsistent baseline data[3, 5, 12, 14].

The results of this study suggested that there were no significant difference between the two groups in perioperative parameters, including intraoperative infusion volumes of crystalloid and colloid, urine output, duration of postoperative hospital stay, and Hb level before discharge. The cell saver group required a lower intraoperative allogeneic RBC transfusion volume (P = 0.021). The results of this study suggested that the cell saver system did not reduce the requirement for allogeneic RBCs during the entire perioperative period (P = 0.051). Considering that the test efficacy was a critical value and the included sample size was only 36 patients in each group, different statistical results might be obtained after expanding the sample size. In addition, although the cell saver system did not reduce the plasma infusion volume after surgery (P = 0.276), the allogeneic plasma requirement was reduced during surgery and throughout the perioperative period (P = 0.011, P = 0.018). These results suggest that, in general, the cell saver system did not reduce the allogeneic RBC and plasma infusion volumes at each stage of the perioperative period, did not reduce blood transfusion-related costs, but it reduced the intraoperative allogeneic RBCs requirement. These findings are still of positive significance to clinicians, potentially leading to a reduction in surgical delays due to insufficient blood stocks.

In this study, the mean intraoperative blood loss for pediatric patients was approximately 1344–1409 ml, while in previous studies [3, 5, 7, 12, 14, 16], the volume of intraoperative blood loss ranged from 400 to 800 ml, less than the blood loss observed in this study. This result may be due to the fact that the 306th Hospital of the People's Liberation Army is one of the first hospitals to perform orthopedic surgery for scoliosis in China and admitted some patients who were referred from other hospitals that did not have the technical capabilities to perform the treatment. Therefore, the disease condition was more severe in patients with scoliosis in this study than in other studies, resulting in more surgical trauma and blood loss. Weinstein et al[19] suggested that 90% of scoliosis patients under 12 years of age had a Cobb angle < 40°. The ages of patients were mostly between 13 and 18 years old, and the preoperative average Cobb angle ranged from 55–68° in some previous studies [3, 5, 7]. This study included 72 pediatric patients with an average age of 10.11–10.93 years old and a body weight of approximately 33.69–34.18 kg. However, the average preoperative Cobb angle was approximately 70.58–75.53°, indicating that the age of patients included in this study was younger but the symptoms of scoliosis were more severe. With the increase in blood loss, the effects of autologous blood collection and reinfusion may decrease, which may be one of the reasons for the inconsistent clinical conclusions. However, the exact cause requires further study.

In summary, the results from this study suggested that during pedicle screw placement for posterior spinal fusion for scoliosis in school-age children, the application of autologous blood reinfusion using a cell saver system reduced the intraoperative allogeneic RBC transfusion volume and the requirement for allogeneic plasma during the entire perioperative period. However, the requirement for allogeneic RBCs was not reduced for the entire perioperative period, and the overall economic efficacy was poor. However this was a retrospective study, a well-designed large-sample RCT should be conducted for further investigation.

Ethics approval and consent to participate

This study was approved by the Institutional Review Board (IRB) of the No. 306 Hospital of the People's Liberation Army and had a retrospective clinical design. The personal information of all patients was anonymized and all methods/protocols were carried out in accordance with the relevant guidelines and regulations. Therefore, the requirement for written informed consent was waived by the IRB/Ethics Committee of the No. 306 Hospital of the People's Liberation Army.

Consent for publication

Not applicable.

Funding

none

Conflict of Interest

none

Acknowledgement

The authors thank Ms. TT Emily for her assistance in reviewing the electronic medical record database and abstracting data.

Author Contribution

Name: YuLiang Miao, MD.

Contribution: This author helped design the study, collate the data, analyze the data, write and approve final manuscript.

Name: Ji Liu, MD.

Contribution: This author helped design the study, complete the statistics, and write and and approve the final manuscript.

Name: LiNa An, MD.

Contribution: This author helped collate and analyze the data, write the Statistics and Discuss sections of the manuscript and approve the final manuscript.

Name: WeiWu Fang, MD.

Contribution: This author helped conceive the study, has principal responsibility for the study, review analysis, write and approve final manuscript.

Data Availability Statement

The ethics committee of hospital 306 informed us that, the data contains potentially identifying information about individual patient, and no licence was received from any one of the patients. Therefore, no detail data should be provided. For more information please contact the ethics committee of the hospital 306, Anxiangbeili No.9, 100101, Beijing, China.

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No competing interests reported.

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Impact of autologous blood reinfusion on blood conservation and economic efficiency during posterior spinal fusion for scoliosis in school-age children

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Data and methods

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Results

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