Are Routine Postoperative Laboratory Tests Really Necessary after High Tibial Osteotomy surgery?

doi:10.21203/rs.3.rs-94008/v2

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Are Routine Postoperative Laboratory Tests Really Necessary after High Tibial Osteotomy surgery?

https://doi.org/10.21203/rs.3.rs-94008/v2

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Background: The purpose of this study was to assess the necessity and cost-effectiveness of routine postoperative laboratory tests for patients undergoing high tibial osteotomy (HTO) surgery.

Methods: A prospective study was conducted and 513 patients with symptomatic isolated medial compartment osteoarthritis received HTO surgery from January 2015 to May 2020 were included in this study. The associations between different clinical factors and postoperative clinical treatment were analyzed. Finally, A logistic regression analysis was performed to detect independent risk factors for patients requiring postoperative clinical treatment.

Results: In this study, 482 patients had completed the full set of postoperative laboratory studies within 3 days after surgery were included in the present study. However, only a small proportion of the patients with anemia (3.9%), hypoalbuminemia (4.1%), and abnormal serum potassium levels (3.5%) required clinical intervention after surgery. Binary logistic regression model analysis showed that body mass index (BMI), preoperative hemoglobin level, estimated blood loss and operative time were the independent risk factors correlated with postoperative blood transfusion in patients with HTO surgery. Female gender and preoperative albumin level were independent risk factors for patients who had requiring albumin supplementation after HTO surgery. Finally, preoperative potassium was the independent risk factors for patients required potassium supplementation postoperatively.

Conclusions: based on the analysis, we conclude that routinely ordering postoperative laboratory studies after HTO surgery are both unnecessary and cost inefficient. However, for patients with identified risk factors, routine postoperative laboratory tests are still needed.

Orthopedic Surgery

high tibial osteotomy

postoperative clinical interventions

postoperative laboratory tests

risk factors

Medial opening wedge high tibial osteotomy (HTO) is an established treatment for medial compartment knee osteoarthritis with varus deformity [1]. As joint preservation surgery, the procedures is intended to restoring the mechanical axis of the lower limb, transferring the load from medial compartment onto the non-affected lateral compartment, and subsequently delay osteoarthritis progression [2].

Many surgeons will routinely perform laboratory tests within 3 days after major orthopedic surgery. Postoperative laboratory tests are ordered to investigation and management of many critical clinical details and potential serious complications [3]. However, with the concept of clinical practice guidelines for enhanced recovery after surgery was gradually introduced and promoted to the field of HTO surgery, orthopedic surgeons are increasingly encouraged to minimizing invasive surgery technique, improving perioperative blood management, and improving patient comfort and satisfaction. Particularly the widespread use of tranexamic acid is a successful milestone of perioperative blood management and perioperative care pathways in HTO surgery field [4, 5].

Cost effectiveness is an increasingly important consideration in the delivery of health care. Recently, several studies have consistently revealed that routine postoperative laboratory tests are not necessary for patients after major orthopedic surgery, unless patients had a history of disease associated with an abnormal laboratory test [6-8]. However, few studies have reported the necessity for routine laboratory tests for patients after HTO surgery.

Thus, this study aimed to evaluate the necessity and cost-effectiveness of routine postoperative laboratory tests for patients after HTO surgery. In addition, we investigate the correlations between the clinical parameters and abnormal postoperative laboratory test results, and identify the risk factors associated with abnormal laboratory test related intervention.

2.1. Patient selection

The ethics committee of our hospital approved the present retrospective study. Patients with symptomatic isolated medial compartment OA who had undergone HTO surgery with normal preoperative laboratory test results from January 2015 to May 2020 were included in the present study.

Diagnosis of patients with OA primarily relies on clinical evidences, standing X-rays and magnetic resonance imaging (MRI). The operative therapy was indicated depending on the degenerative process, and evaluated by the X-ray classification of K-L. All patients had an identical operative approach. An initial knee arthroscopy was performed to treat any intraarticular pathology. Patients were allowed to walk non-weight-bearing with two crutches for six weeks, and full weight-bearing was permitted six weeks after surgery.

Patients undergoing HTO for other indications (cartilage resurfacing or ligament reconstruction), and previous tibia or femur fracture were excluded from the study. Furthermore, Patients presenting with a history of antiplatelet therapy, malignant tumors, significant hematologic disorders, and infectious or systematic inflammatory disease were excluded from this study.

2.2. Data collection

HTO was performed or directly supervised by a consultant surgeon. All the patients’ demographics and clinical characteristics were carefully recorded, including: age, gender and body mass index (BMI), comorbidities (diabetes mellitus, high blood pressure, alcohol consumption status and smoking status), and surgery related factors (intraoperative blood loss and transfusion, operative time and tranexamic acid use), preoperative and postoperative routine laboratory test results, and any medical intervention that is directly related to abnormal laboratory values (including: blood transfusion, albumin supplementation, electrolyte supplementation).

In our institution, normal laboratory values are defined as follows: hemoglobin (115–150g/L), and platelets (125–350*10^9/L), alanine

aminotransferase (9-50IU/L), aspartate aminotransferase (15-40IU/L), albumin (40–55g/L), creatinine (44-115umol/L), blood urea nitrogen(1.70-8.30mmol/L), uric acid (170-420ummol/L), serum sodium (137–147mmol/L), serum potassium (3.5–5.3mmol/L) and serum calcium (2.0–2.6mmol/L). An abnormal preoperative or postoperative laboratory test results will be identified if recorded outside of the corresponding reference interval.

Aggressive interventions were not routinely performed for patients with abnormal preoperative laboratory tests before HTO surgery, unless they met the criteria for clinical intervention. Patients with levels of hemoglobin <70 g/L or symptomatic anemia with a hemoglobin level of >70 g/L, albumin level <30 g/L, and serum potassium <3.5 mmol/L were considered to require clinical intervention [9]. During the study period, all HTO surgery patients’ routine underwent intravenous injection of 1.5 g tranexamic acid 30 minutes before the incision, who also received articular injection of 0.5g tranexamic acid after it was sutured.

2.3. Statistical analysis

Qualitative variables were expressed as frequency and percentages, and were assessed by the Chi-square test. Quantitative variables were presented as mean value ± standard deviation, and the two groups were compared using the independent samples t tests. Binary logistic regression model was used to identify the independent risk factors for patients with abnormal laboratory test results who required postoperative clinical treatment. Receiver operating characteristic (ROC) curve was used to assess the predictive value of risk factors for postoperative clinical treatment. All analysis was performed by SPSS Version 22 (SPSS Inc. Chicago IL). And P < 0.05 was considered statistically significant.

3.1. Patient demographics

A total of 513 patients were evaluated, of these patients, 482 patients had completed the full set of postoperative laboratory studies within 3 days after surgery were included in the present study. The majority of abnormal postoperative laboratory test results were hypoalbuminemia, which accounts for 44.0% (212cases) of the patients. However, only a small proportion of the patients with anemia (3.9%), hypoalbuminemia (4.1%), and abnormal serum potassium levels (3.5%) required clinical intervention after surgery (Table 1).

3.2. Risk Factors for Patients Requiring Postoperative Clinical Treatment

Based on the analysis, there were no statistically significant differences on age and comorbidities between HTO patients with and without postoperative blood transfusion (P >0.05, respectively). However, the BMI, estimated blood loss and operative time were significantly higher in patients with postoperative blood transfusion compared to those without postoperative blood transfusion (p<0.001, respectively). And the preoperative hemoglobin level was significantly lower in patients with postoperative blood transfusion than those of non postoperative blood transfusion patients (p<0.001). Furthermore, female genders were more likely required blood transfusion (Table 2). Binary logistic regression analysis indicated that BMI (OR = 0.584, P=0.004), preoperative hemoglobin level (OR =1.205, P <0.001), estimated blood loss (OR = 0.991, P <0.001) and operative time (OR =0.976, P <0.024) were the independent risk factors correlated with postoperative blood transfusion in patients with HTO surgery (Table 3).

The univariate and binary logistic regression analysis results showed that female (OR =0.163, P =0.001) and preoperative albumin level (OR =1.453, P <0.001) were independent risk factors for patients who had requiring albumin supplementation after HTO surgery (Tables 4 and 5).

For patients who had and had not required postoperative potassium supplementation, significant differences were found for preoperative potassium and operative time (P < 0.05; Table 6). Furthermore, the binary logistic regression analysis was carried out to identify the independent risk factors for potassium supplementation in patients with HTO surgery. The results showed that preoperative potassium (OR =19.870, P <0.001) were the independent risk factors for patients required potassium supplementation postoperatively (Table 7).

3.3. The diagnostic accuracy of risk factors for predicting postoperative clinical treatment

The ROC curve was analyzed to determine the values of risk factors for predicting postoperative clinical treatment in patients with HTO surgery. The accuracy was analyzed by the area under the curve (AUC). The results were demonstrated in Table 8. The results indicated that preoperative hemoglobin level had the highest diagnostic accuracy for predicting transfusion in patients with HTO surgery (AUC = 0.947, P<0.001)

The recent years have witnessed unprecedented improvement in both modern-day surgical technique and perioperative care pathways. Particularly the widespread use of tranexamic acid is a successful milestone for perioperative blood management and perioperative care pathways for HTO [9]. Cost effectiveness is an increasingly important consideration in the delivery of health care. Recently, several studies have consistently revealed that routine postoperative laboratory tests are not necessary for patients after major orthopedic surgery. Instead, only patients with risk factors should undergo routine postoperative laboratory tests [9, 10]. To improve the quality of medical care and reduce the expenditure of medical expenses, many studies have recommended reducing the use of duplicative and limited clinical value laboratory tests [10].

Previous studies have indicated that the more laboratory tests performed on patients, the more likely they are to find something unusual [11]. Recently, several studies have consistently revealed that routine postoperative laboratory tests are not necessary for patients after major orthopedic surgery, also suggested the majority of the information provided by these abnormal test results was considered to be of no clinical significance, only patients with risk factors should undergo routine postoperative laboratory tests. Wu et al [9] showed that up to 88.4% of patients had abnormal postoperative laboratory results, only 6.8% of those patients required a postoperative medical intervention, which indicated that routine postoperative laboratory tests are unnecessary for most patients. Serum laboratory tests are routinely ordered after HTO, but at our institution they are rarely abnormal. Furthermore, these infrequently abnormal serum laboratory values rarely require active intervention, which indicated that routine postoperative laboratory tests are not necessary for most patients after HTO surgery.

Park et al [12] found that risk factors for transfusion are higher BMI, estimated blood loss, and lower preoperative hemoglobin levels. Wu et al [9] retrospectively reviewed 349 patients who underwent primary elective unilateral total hip arthroplasty from January 2016 to November 2018 at a single institution, and the long operation time and low preoperative hemoglobin level were most predictive. Halawi et al [13] found that BMI> 35 kg/m2, anemia and estimated blood loss > 250mL was an independent risk factor for transfusion. Greco et al [14] propose that routine postoperative laboratory tests should be considered in patients presenting with a preoperative hemoglobin level below 130 g/l and postoperative clinical symptoms or signs of significant blood loss. Similarly, we also identified BMI>23.15 kg/m2, preoperative hemoglobin level <112.5 g/L, estimated blood loss>225ml and operative time >164.5mins as independent risk factors for the requirement for a blood transfusion after HTO surgery.

In a retrospective study, Lin et al [10] investigated 1915 patients with lumbar spinal surgery, and found that the incidences of abnormal postoperative serum albumin was 77.36%, however, only 1.95% of those patients required albumin supplementation. In our study, we demonstrated an incidence as great as 44.0% in patients after HTO, and found that the incidence of albumin supplementation was 4.1%, slightly greater than that reported by Lin et al [10]. Hart et al [15] reported that female gender was an independent risk factor associated with the need for clinical treatment, the reason might be that female patients are always accompanies with a greater chance to anemia and hypoproteinemia. Wu et al [9] showed that female gender, long operation time, and low preoperative albumin level were risk factors for patients requiring albumin supplementation. In the present study, we found that risk factors for albumin supplementation are female gender and low preoperative albumin level, which is in accordance with previous studies,

In a retrospective study, Kildow et al [7] investigated the results of basic metabolic panel values of 767 patients, and found that the incidences of potassium abnormalities were 25.2% after primary total joint arthroplasty. Among the most significant risk factors for electrolyte abnormalities were female gender, advanced age, and diabetes. Lin et al [10] reported that the incidence of abnormal electrolytes was low and the predictive value was small, 0.92% of the patients undergoing lumbar spinal surgery were diagnosed with hypokalaemia postoperatively required postoperative clinical treatment. Likewise, Greco et al [14] demonstrated an incidence as great as 15.5% for patients who were provided electrolyte supplementation after total joint arthroplasty. The majority of these patients presented with a potassium level less than 4mmol/L during preoperative testing. In line with previous studies, we found that 3.55% of patients required potassium supplementation after HTO surgery. The preoperative potassium was lower in patients with potassium supplementation and identified as an independent risk factor for postoperative clinical treatment in patients with HTO surgery. The cutoff value of it was 3.45mmol/L. It suggested that preoperative potassium level <3.45mmol/L predicted patient at a high risk of postoperative clinical treatment.

To the best of our knowledge, this study will be the first study in to evaluate the necessity of postoperative laboratory tests for Chinese patients after primary HTO. Although the results were interesting, the limitations of this study still existed. First of all, this is a single tertiary academic center study, and a relative small sample may result in bias to the outcomes. Secondly, our transfusion criteria were somewhat subjective, as our protocol set a restrictive transfusion strategy hemoglobin level <70 g/L or symptomatic anemia with a hemoglobin level >70 g/L, which might limit the generalizability of the study findings. Thus, further study with large sample and multi-center investigation is necessary to verify the efficacy of these risk factors for predicting postoperation medical intervention in patients following HTO surgery.

In summary, based on the analysis, only a small number of patients required postoperative clinical interventions in response to abnormal laboratory values, we conclude that routinely ordering postoperative laboratory studies after HTO surgery are both unnecessary and cost inefficient. However, for patients with identified risk factors, routine postoperative laboratory tests are still needed. We recommend to selectively consider obtaining a postoperative complete blood count in patients presenting with a BMI>23.15 kg/m2, preoperative hemoglobin level <112.5g/l, estimated blood loss >225ml and operative time >164.5mins. Further, we suggest that selectively consider obtaining a postoperative basic metabolic panel in patients with a preoperative potassium level <3.45mmol/l, female gender and preoperative albumin level <38.95g/L. However, larger sample sizes and multicenter studies are necessary to verify our results.

HTO:high tibial osteotomy; BMI:body mass index; MRI: magnetic resonance imaging; K-L: Kellgren-Lawrence; ROC: Receiver operating characteristic; AUC: under the curve;

Ethics approval and consent to participate

This study was approved by the ethics committee of the Jiangxi Provincial People’s Hospital Affiliated to Nanchang University. All patients agreed and signed to participate on this clinical trial. All procedures performed in this study involving human participants were in accordance with the bioethical standards of the institutional and the national research committee and with the 1964 Helsinki declaration and its later amendments.

Consent for publication

Written informed consent was obtained from each patient to authorize the publication of their data

Availability of data and materials

All the data will be available upon motivated request to the corresponding author of the present paper.

Conflicts of Interest:

No benefits in any form have been or will be received from any commercial party related directly and indirectly to the subject of this manuscript.

Funding

No funding was obtained for this study.

Authors’ Contribution:

LM contributed to the study conception and design. Material preparation, data collection and analysis were performed by LXG and TZM. The first draft of the manuscript was written by LM and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Acknowledgements：

The first and second author (Nie si and Li hong-bo) contributed equally to this study and share the first authorship.

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Table 1. Results of Routine Laboratory Tests for Patients Undergoing HTO Surgery

Laboratory Test (n=482)	ALTR (n; %)	PCTR (n; %)
Routine blood test
Hemoglobin	106(22.0%)	19(3.9%)
Platelets	36(7.5%)	0 (0)
Liver function test
Alanine aminotransferase	6(1.2%)	0 (0)
Aspartate aminotransferase	178(36.9%)
Albumin	212(44.0%)	20(4.1%)
Renal function test
Creatinine	77(16.0%)	0 (0)
Blood urea nitrogen	2(0.4%)	0 (0)
Coagulation function
PT	30(6.2%)	0 (0)
APTT	50(10.4%)	0 (0)
Electrolytes
Serum sodium	32(6.6%)	0 (0)
Serum potassium	17(3.5%)	17(3.5%)
Serum calcium	19(3.9%))	0 (0)

ALTR: abnormal postoperative laboratory test result; PCTR: postoperative clinical treatment required; PT: prothrombin time; APTT: activated partial thromboplastin time;HTO: high tibial osteotomy

Table 2. Postoperative Blood Transfusion for Patients with Abnormal Hemoglobin after HTO Surgery

Factor	Treatment Group (n=19)	No Treatment Group (n=463)	P value
Age (years)	53.58±5.99	53.30±5.92	0.846
Gender (n)			0.032
Male	8	317
Female	11	146
BMI (kg/m2)	26.25±3.35	23.04±2.88	p<0.001
Smoking: n(%)	3(15.8%)	133（28.7%）	0.219
Alcohol use: n(%)	2(10.5%)	94（20.3%）	0.142
Diabetes mellitus: n(%)	31(5.8%)	30（6.5%）	0.390
High blood pressure: n(%)	4(21.1%)	61(13.2%)	0.306
Preoperative hb level (g/L)	104.05±14.33	135.94±12.20	p<0.001
Estimated blood loss (mL)	489.47±216.40	233.05±87.34	p<0.001
Operative time (minutes)	174.62±47.62	145.74±23.25	p<0.001

BMI: body mass index; HTO: high tibial osteotomy; hb: hemoglobin

Table 3. Risk Factors for Postoperative Blood Transfusion in Patients Undergoing HTO Surgery

Risk factor	odds ratio	95 % confidence interval	P value
Gender	2.819	0.339-23.453	0.338
BMI	0.584	0.404-0.845	0.004
Preoperative hb level	1.205	1.096-1.325	p<0.001
Estimated blood loss	0.991	0.986-0.996	p<0.001
Operative time	0.976	0.955-0.997	0.024

BMI: body mass index; HTO: high tibial osteotomy

Table 4 Clinical Characteristics of Patients Who Required Postoperative Albumin Supplement

Factor	Treatment Group (n=20)	No Treatment Group (n=462)	P value
Age (years)	54.65±6.71	53.26±5.88	0.303
Gender (n)			0.032
Male	7	318
Female	13	144
BMI (kg/m2)	23.87±3.99	23.14±2.92	0.283
Smoking: n(%)	2(10.0%)	134（29.0%）	0.064
Alcohol use: n(%)	2(10.0%)	94（20.3%）	0.392
Diabetes mellitus: n(%)	3(15.0%)	30（6.5%）	0.150
High blood pressure: n(%)	3(15.0%)	63(13.6%)	0.746
Preoperative Albumin (g/L)	34.99±4.02	42.27±5.22	p<0.001
Estimated blood loss (mL)	285.00±190.64	241.34±102.47	0.076
Operative time (minutes)	141.25±16.86	147.12±25.50	0.308

BMI: body mass index

Table 5. Risk Factors for Patients Requiring Postoperative Albumin Supplementation

Risk factor	odds ratio	95 % confidence interval	P value
Gender	0.163	0.057-0.470	0.001
Preoperative Albumin level	1.453	1.268-1.664	p<0.001

Table 6. Clinical Characteristics of Patients Who Required Postoperative Potassium Supplementation

Factor	Treatment Group (n=17)	No Treatment Group (n=465)	P value
Age (years)	54.00±6.86	53.29±5.89	0.627
Gender (n)			0.159
Male	7	318
Female	10	147
BMI (kg/m2)	23.30±3.74	23.16±2.94	0.852
Smoking: n(%)	1(5.9%)	135（29.0%）	0.051
Alcohol use: n(%)	1(5.9%)	95（20.4%）	0.216
Diabetes mellitus: n(%)	2(11.8%)	31（6.7%）	0.327
High blood pressure: n(%)	3(17.6%)	63(13.5%)	0.716
Preoperative Potassium (g/L)	3.68±0.53	4.10±0.38	0.006
Estimated blood loss (mL)	264.71±158.87	242.37±105.41	0.401
Operative time (minutes)	136.59±11.24	147.25±25.51	0.002

BMI: body mass index

Table 7. Risk Factor for Patients Requiring Postoperative Potassium Supplementation

Risk factor	odds ratio	95 % confidence interval	P value
Preoperative Potassium	19.870	4.805-82.166	p<0.001
Operative time	1.025	0.997-1.054	0.082

Table 8. Cutoff Values of Risk Factors for Patients Requiring Postoperative Clinical Treatment

Treatment	Risk factors	Cut-off value	Sensitivity	Specificity	AUC	p
Transfusion	BMI	23.15	89.5%	55.3%	0.770	<0.001
	Preoperative hb level	112.5	78.9%	97.0 %	0.947	<0.001
	Estimated blood loss	225	89.5%	81.2 %	0.888	<0.001
	Operative time	164.5	63.2%	81.4%	0.669	0.003
Albumin	Female gender	-	-	-	0.669	0.010
	Preoperative albumin level	38.95	95.0%	76.4 %	0.879	<0.001
Potassium	Preoperative potassium	3.45	41.2%	97.4%	0.707	0.004

BMI: body mass index; AUC: area under the curve.

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You are reading this latest preprint version

Are Routine Postoperative Laboratory Tests Really Necessary after High Tibial Osteotomy surgery?

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Version 2

Abstract

Background

Methods

Results

Discussion

Conclusion

Abbreviations

Declarations

References

Tables

Status:

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