Is Routine Hemoglobin Monitoring Necessary after Elective Hip and Knee Arthroplasty?

Postoperative laboratory testing in the era of outpatient total joint arthroplasty: Targeted patient selection and associated cost savings

Background

With the advent of outpatient total joint arthroplasty (TJA), the days of routinely drawing postoperative labs (complete blood counts [CBCs] and metabolic panels [CMPs/BMPs]) to monitor for complications are behind us. However, there does exist a subset of at-risk patients that may benefit from diligent postoperative monitoring, though the circumstances under which labs should be ordered remains unclear and subject to surgeon discretion. A systematic review of the literature was therefore conducted to evaluate the utility of postoperative laboratory testing, approaches to targeted patient selection and associated cost-savings.

Methods

The PubMed, MEDLINE, EBSCOhost, and Google Scholar electronic databases were searched on August 17, 2023, to identify all studies published since January 1, 2000, that evaluated the role of postoperative lab testing in TJA. (PROSPERO study protocol registration: CRD42023437334). Articles were included if a full-text English manuscript was available and the study assessed the utility of routine postoperative labs in TJA. 19 studies were included comprising 34,166 procedures. The mean Methodological index for Nonrandomized Studies score was 18.2 ± 1.5.

Results

Abnormal postoperative lab results were common and infrequently required clinical intervention. Among several identified risk factors for patients that may benefit from postoperative laboratory monitoring, preoperative lab values proved excellent discriminators of transfusion requirement and metabolite-associated intervention. Selective testing demonstrated the ability to generate substantial cost-savings.

Conclusion

Routine postoperative laboratory testing offers little clinical utility and produces unnecessary expenditures. Preoperative lab values offer the greatest predictive utility for postoperative transfusion requirement and metabolite-associated clinical intervention, with a preoperative hemoglobin threshold of 111.5 g/L offering an area under the curve (AUC) of 0.93 for predicting postoperative transfusion. Further investigations are needed for metabolic panel predictive models and should incorporate preoperative lab values. The refinement of such models can enable targeted patient selection to avoid unnecessary labs and generate substantial cost savings without compromising patient safety.

Re-evaluating the Need of Postoperative Blood Testing in Low-Risk Patients After Primary Elective Arthroplasty: A Single-Centre Retrospective Analysis

Introduction Increasing demand and financial burdens are placing significant strain on current health resources. To help ease pressures, there has been increased emphasis on improving patient flow and saving costs within the health service. Routine postoperative blood tests in otherwise healthy patients may add to delays and healthcare costs without influencing subsequent management. Recent studies suggest that routine postoperative blood tests may be unnecessary in fit and healthy patients undergoing elective arthroplasty. We aimed to assess this practice at our institution in the American Society of Anaesthesiologists (ASA) grade 1 and 2 patients undergoing elective hip and knee arthroplasty. Methods We conducted a retrospective review of 1595 consecutive elective hip and knee replacements in ASA 1 and ASA 2 patients at our institution over a one-year period from 2021 to 2022. Operation notes and electronic databases were analyzed to collect data regarding demographics, co-morbidities, treatment, pre and postoperative blood tests, and any documented interventions in these patients. Binomial logistic regression was employed to identify risk factors associated with postoperative abnormalities and the need for clinical intervention.  Results Postoperative blood abnormalities were identified in 75.4% of patients, primarily anaemia (69.2%) and hyponatremia (29.9%). Anaemia was similarly prevalent in both total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients, with 70.2% affected in each group, although the majority of cases were mild (83.8% in THA and 90.5% in TKA). Hyponatremia was significantly more common in TKA patients (40.3%) compared to THA patients (19.3%), although most cases were mild in severity. Only 5% of cases required any intervention, with higher rates observed in the TKA group compared to the THA group (p=0.008). Blood transfusion rates were low, occurring in 0.6% of cases. Factors associated with postoperative anaemia included higher BMI, preoperative antiplatelet use, and lower preoperative haemoglobin levels, while postoperative hyponatremia was linked to preoperative sodium levels, loop diuretic use, and PPI use. Acute Kidney Injury (AKI) was identified in 2.2% of patients and was predominantly mild. Potassium abnormalities were infrequent, with hypokalemia occurring in 1.5% of patients and no cases of hyperkalemia in our series. Conclusions Although postoperative blood test abnormalities were common, the majority were mild and rarely influenced management in this low-risk cohort of patients, with overall low postoperative intervention rates. Selective blood testing may allow safe targeted testing in this low-risk cohort of patients, minimizing costs and saving valuable resources.

Are Routine Postoperative Hemoglobin Tests Justified in All Patients Who Undergo Total Hip Arthroplasty Due to a Displaced Femoral Neck Fracture?

Background: Total hip arthroplasty (THA) is a standard treatment for a displaced femoral neck fracture in the elderly. In contemporary healthcare, there is a global shift towards fast-track treatment modalities, prioritizing early hospital discharge for patients. Consequently, routine postoperative blood tests may become redundant, offering significant time and cost savings. We aim to evaluate postoperative hemoglobin levels in trauma-related THA cases and identify patient profiles for whom these tests hold significance. Methods: A retrospective review of 176 THA procedures performed between 2018 and 2022, focusing on individuals undergoing THA for displaced femoral neck fractures. Multivariable logistic regression analysis was employed to identify factors associated with postoperative hemoglobin levels below 8.5 g/dL. Results: Of the 176 patients included, 109 (61.9%) were women and the mean age was 69.09 ± 8.13 (range 27 to 90) years. The majority of the patients underwent surgery within 48 hours of admission. The mean preoperative hemoglobin (Hb) level was 13.1 ± 1.4 g/dL, while the mean postoperative Hb level was 10.5 ± 1.2 g/dL. Only six patients (3.41%) exhibited postoperative Hb levels of ≤8.5 g/dL. No significant associations were found between postoperative Hb levels ≤ 8.5 and any demographic, surgical, or medical characteristics. Conclusions: Our findings suggest that routine postoperative blood count testing may not be necessary for most patients undergoing THA for displaced femoral neck fractures, particularly those without complications or significant comorbidities.

Risk factors for blood transfusion and postoperative anaemia following total knee arthroplasty

Aims

Blood transfusion and postoperative anaemia are complications of total knee arthroplasty (TKA) that are associated with substantial healthcare costs, morbidity, and mortality. There are few data from large datasets on the risk factors for these complications.

Methods

We retrospectively reviewed the records of TKA patients from a single tertiary care institution from February 2016 to December 2020. There were a total of 14,901 patients in this cohort with a mean age of 67.9 years (SD 9.2), and 5,575 patients (37.4%) were male. Outcomes included perioperative blood transfusion and postoperative anaemia, defined a priori as haemoglobin level < 10 g/dl measured on the first day postoperatively. In order to establish a preoperative haemoglobin cutoff, we investigated a preoperative haemoglobin level that would limit transfusion likelihood to ≤ 1% (13 g/dl) and postoperative anaemia likelihood to 4.1%. Risk factors were assessed through multivariable Poisson regression modelling with robust error variance.

Results

In multivariable analyses, each gram of tranexamic acid reduced transfusion likelihood by 39% (adjusted risk ratio (ARR) 0.61 (95% confidence interval (CI) 0.47 to 0.78)). Risk factors associated with an increased risk of transfusion included operating time (ARR 2.07 (95% CI 1.54 to 2.77)) and drain use (ARR 1.73 (95% CI 1.34 to 2.24)).

Conclusion

In this study, we found that increased tranexamic acid dosing, decreased operating time, and decreased drain use may reduce transfusions following TKA. We also established a single preoperative haemoglobin cutoff of 13 g/dl that could help minimize transfusions and reduce postoperative complete blood counts.

Are Risk Factors for Postoperative Significant Hemorrhage following Total Knee Arthroplasty Potentially Modifiable? A Retrospective Cohort Study

Total knee arthroplasty (TKA) is the treatment of choice for end-stage osteoarthritis (OA) of the knee, because it alleviates pain and restores function of the knee. However, TKA-associated hemorrhage and subsequent anemia remain a concern. Most previous studies have defined meaningful postoperative bleeding as blood loss > 500 mL or hemoglobin (Hb) drop > 20 g/L. Therefore, we defined significant hemorrhage as a postoperative Hb drop more than 20 g/L in this study, and we investigated possible risk factors related to significant hemorrhage in TKA and whether these risk factors are modifiable. This retrospective study was conducted through a comprehensive review of the perioperative records of patients with OA of the knee who underwent TKA between January 2009 and December 2015 at our hospital. Patients were allocated into two groups: patients in Group A had their Hb drop ≤ 20 g/L; patients in Group B had their Hb drop > 20 g/L. Factors analyzed included sex, age, body mass index (BMI), the American Society of Anesthesiologists (ASA) classification, comorbidities, preoperative platelet count, use of tranexamic acid (TXA), operation time, and type of anesthesia. A total of 3350 patients met the criteria for analysis, with 1782 patients allocated to Group A and 1568 patients to Group B. Five independent risk factors for significant hemorrhage were identified: male sex (odds ratio(OR), 1.29; 95% confidence interval(CI), 1.08−1.53; p = 0.005), age (OR, 1.02; 95% CI, 1.01−1.03; p = 0.001), use of TXA (OR, 0.39; 95% CI, 0.34−0.45; p < 0.001), spinal anesthesia versus general anesthesia (OR, 0.71; 95% CI, 0.56−0.90; p = 0.004), and preoperative platelet count (OR, 0.96; 95% CI, 0.93−0.98; p = 0.001). Of these identified risk factors, preoperative platelet count, use of TXA, and spinal anesthesia are modifiable. These potentially modifiable risk factors need to be taken into consideration when making both the perioperative care and anesthesia plan by surgeons and anesthesiologists, especially in patients at risk of significant hemorrhage.