The Utility of Basic Metabolic Panel Tests After Total Joint Arthroplasty

Postoperative Prevalence and Risk Factors for Serum Hypokalemia in Patients with Primary Total Joint Arthroplasty

OBJECTIVE

Regular monitoring of serum potassium after a total joint arthroplasty (TJA) is a form of routine examination that can help detect abnormal serum potassium levels and reduce the incidences of adverse events that may occur on account of postoperative hypokalemia. Previous studies rarely discussed hypokalemia after joint replacement. In the present study, our primary goal was to investigate the incidence and possible risk factors of hypokalemia after a total hip and knee replacement procedure was performed.

METHODS

This study included patients who underwent a unilateral total knee or hip arthroplasty in our department between April 2017 and March 2018. Serum potassium levels pre and post operation were collected and retrospectively analyzed. The differences in age, gender, body mass index (BMI), history of diseases, red blood cell (RBC), hemoglobin, hematocrit, glomerular filtration rate, ejection fraction, blood glucose, urine creatinine, urea nitrogen, intraoperative blood loss, operation time, drainage, preoperative potassium, surgery type, were compared between those patients diagnosed with hypokalemia and their non-hypokalemia at different times post surgery. Thereafter, the risk factors of postoperative hypokalemia patients were analyzed using statistical procedure multiple logistic regression model.

RESULTS

The risk of hypokalemia after TJA was 53.1%, while, that on the first, third, and fifth day after operation was 12.5%, 40.7%, and 9.6% respectively. The serum potassium level on the first, third, and fifth postoperative days was 3.84 ± 0.32, 3.59 ± 0.34, and 3.80 ± 0.32 mmol/l, respectively. However, the level on the third day appeared to be the lowest (p = 0.015) of them all. The independent risk factors for hypokalemia after a total hip and knee replacement were the level of preoperative serum potassium concentration (p = 0.011), preoperative red blood cells counts (p = 0.027), and history of diabetes (p = 0.007).

CONCLUSION

Regular monitoring of serum potassium concentration should be performed post TJA. We need to pay more attention to the patient's preoperative potassium levels along with their red blood cell counts especially in patients diagnosed with type 2 diabetes mellitus.

The incidence and risk factors for abnormal postoperative blood tests following primary total joint replacement

Aims

We aim to evaluate the usefulness of postoperative blood tests by investigating the incidence of abnormal results following total joint replacement (TJR), as well as identifying preoperative risk factors for abnormal blood test results postoperatively, especially pertaining to anaemia and acute kidney injury (AKI).

Methods

This is a retrospective cohort study of patients who had elective TJR between January and December 2019 at a tertiary centre. Data gathered included age at time of surgery, sex, BMI, American Society of Anesthesiologists (ASA) grade, preoperative and postoperative laboratory test results, haemoglobin (Hgb), white blood count (WBC), haematocrit (Hct), platelets (Plts), sodium (Na+), potassium (K+), creatinine (Cr), estimated glomerular filtration rate (eGFR), and Ferritin (ug/l). Abnormal blood tests, AKI, electrolyte imbalance, anaemia, transfusion, reoperation, and readmission within one year were reported.

Results

The study included 2,721 patients with a mean age of 69 years, of whom 1,266 (46.6%) were male. Abnormal postoperative bloods were identified in 444 (16.3%) patients. We identified age (≥ 65 years), female sex, and ASA grade ≥ III as risk factors for developing abnormal postoperative blood tests. Preoperative haemoglobin (≤ 127 g/dl) and packed cell volume (≤ 0.395 l/l) were noted to be significant risk factors for postoperative anaemia, and potassium (≤ 3.7 mmol/l) was noted to be a significant risk factor for AKI.

Conclusion

The costs outweigh the benefits of ordering routine postoperative blood tests in TJR patients. Clinicians should risk-stratify their patients and have a lower threshold for ordering blood tests in patients with abnormal preoperative haemoglobin (≤ 127 g/l), blood loss > 300 ml, chronic kidney disease, ASA grade ≥ III, and clinical concern.

How to avoid systematic postoperative blood test after total hip arthroplasty: A new risk scoring system compared to Wu's score

BACKGROUND

Routine laboratory studies are often performed following total hip arthroplasty (THA). However, lately, their necessity has been challenged and risk factors for postoperative transfusion are still debated. Recently, a risk scoring system to single out patients that should have a postoperative blood test has been published by Wu et al. The purposes of this retrospective study were: (1) to validate this recently published risk scoring system to identify patients who should have a postoperative laboratory test; (2) to single out risk factors of postoperative transfusion; (3) to determine if another score can more accurately predict the need for postoperative transfusion.

HYPOTHESIS

Wu et al.'s risk scoring system can accurately identify patients who should have a postoperative blood test.

METHODS

In all, 1693 patients who underwent primary THAs between June 2015 and October 2020 were screened for potential eligibility to include 1000 patient for analysis. Preoperative and postoperative blood tests were done for every patient. Clinical information and laboratory results were retrospectively collected and analyzed. A descriptive analysis followed by univariate and multivariate analysis were sequentially performed. A multiple logistic regression model was employed to determine a formula predicting the transfusion risk called THABUS for Total Hip Arthroplasty Blood test Usefulness Score. The risk scoring system for complete blood count published by Wu et al. in may 2020 was performed for every patient and compared to the THABUS predictive model.

RESULTS

The transfusion rate was 2.3% (23/1000). The risk-scoring system published by Wu and al. showed that a laboratory test was necessary for 60.6% (606/1000) however 13% (3/23) of the patients who needed a blood transfusion were missed by the risk-scoring system, giving it a sensitivity of 86.95% and a specificity of 40%. Increasing age, arterial hypertension, female gender, low preoperative hemoglobin, ASA score≥2 and diagnosis of osteonecrosis of the femoral head were significantly associated with postoperative transfusion. The THABUS formula can predict the risk for transfusion with a sensibility of 96.65% and a specificity of 75.54%. In our cohort of 1000 patients, following the THABUS formula would have led to 261 postoperative blood test and cost savings of 32,132$. Only one patient (4.3%) was missed by our new score. The THABUS formula is significantly better than Wu et al.'s complete blood count score in identifying both patient that will need a transfusion (p<0.01) and those who shouldn't have a postoperative blood test (p<0.001). Medical intervention because of creatinine or electrolytes abnormality was needed in 0.3% (3/1000) of patients.

DISCUSSION

In this study Wu et al.'s recently published complete blood count risk-scoring system was not validated. However, in the studied population the THABUS formula can accurately target patients who might need a transfusion. The use of the THABUS formula could reduce hospitalization costs without compromising the patients' safety.

LEVEL OF EVIDENCE

III, case-control study.

Predicting Factors for Requiring Routine Postoperative Blood Analysis in Primary Hip and Knee Arthroplasty: A Prospective Study

Background Minimising unnecessary expenditure is essential to cope with high demands on the health sector. A set of full blood count, electrolyte, creatinine and urea tests cost £12 in the National Health Service (NHS). Identifying selected patients requiring postoperative blood tests following primary knee and hip arthroplasty will avoid unnecessary tests and help to reduce expenditure.  The aim of our study is to propose criteria for requesting postoperative blood tests that are safe and do not miss patients. Materials and methods We prospectively evaluated 126 patients (72 in the total knee replacement (TKR) group and 54 in the total hip replacement (THR) group) who underwent either an elective primary THR or a TKR. The mean patient age was 71 years. Patient demographics as well as in-patient events throughout each patient's hospital stay were recorded. Hospital readmissions were also monitored for up to 90 days postoperatively.  Statistical analysis was performed using SPSS Statistics software (IBM Corp., Armonk, NY) with paired t-tests / Wilcox and mixed measures analysis of variance. Binary logistic regression was used to identify predictors of patients requiring a postoperative blood test. Results Analysis of our data identified the following as risk factors for requiring postoperative full blood count tests, including pre-operative Hb of ≤ 110 g/L, cardiac disease, clinical features of anaemia postoperatively and intraoperative blood loss of > 500 mL. The additional risk factors identified for requiring postoperative electrolyte and urea tests are deranged pre-operative electrolytes and clinical signs or symptoms of electrolyte/renal disturbance such as anuria. No patient was readmitted within 90 days of discharge. Conclusion Overall, applying the criteria we have devised would have saved 74 blood tests in the cohort of 126 patients. This provides an odds ratio of 14.0 (95% confidence interval: 1.77-110, p=0.012) of an abnormal result in the patients that would have been tested, compared to those that would not have been tested.

Routine Laboratory Tests are not Necessary After Primary Total Joint Arthroplasty: A Prospective Study Utilizing a Selective Algorithmic Approach

BACKGROUND

Laboratory tests are obtained following total joint arthroplasty (TJA) despite a lack of supporting evidence. No prior study has prospectively analyzed the effect of discontinuing routine laboratory tests. This study aimed to determine whether discontinuing routine laboratory tests in TJA patients resulted in a difference in 90-day complications.

METHODS

This was a prospective protocol change study at a high-volume center. Prior to protocol change, patients underwent routine laboratory tests following primary unilateral TJA (control group). After the change, an algorithmic approach was used to selectively order laboratory tests (protocol group). Patients with bleeding disorders, chronic obstructive pulmonary disease, arrhythmia, coronary artery disease, congestive heart failure, chronic renal failure, dementia, abnormal preoperative sodium, potassium, or hemoglobin <10 g/dL were excluded. In-hospital and 90-day data were collected. Student's t-test was used to analyze continuous variables and chi-squared test was used for categorical variables. A pre-hoc analysis examining the primary outcome required 607 patients per group to achieve 80% power.

RESULTS

The protocol group included 937 patients, whereas the control group included 891 patients. The protocol group had fewer females and total hip arthroplasties. There were no differences in age, body mass index, American Society of Anesthesiologists classification, tranexamic acid administration, or estimated blood loss between the protocol and control groups. There were also no differences in transfusions, electrolyte corrections, unplanned consults, length of stay, or transfers. The protocol cohort had more fluid boluses and home discharges. There was no difference in 90-day complications between the 2 groups.

CONCLUSIONS

This study utilizing an algorithmic approach to laboratory collection demonstrates that discontinuing routine laboratory tests following TJA is safe and effective. We believe this protocol can be implemented for most patients undergoing primary unilateral TJA.

Tradition Versus Value: Is There Utility in Protocolized Postoperative Laboratory Testing After Elective Colorectal Surgery?

OBJECTIVE

Determine if routine ordering of postoperative day 1 (POD 1) serum laboratory tests after elective colorectal surgery are clinically warranted and valuable given the associated costs of these lab tests.

SUMMARY OF BACKGROUND DATA

Routine postoperative serum laboratory tests are a part of many colorectal surgery order sets. Whether these protocolized lab tests represent cost-effective care is unknown.

METHODS

Patients undergoing elective colorectal surgery between January 1, 2015 and December 31, 2017 at our institution were identified. The protocolized POD 1 lab tests obtained as part of the postoperative order set were reviewed to determine the rate of abnormal values and any intervention in response. Costs associated with protocolized laboratory testing were calculated using dollar amounts representing 2017 outpatient Medicare reimbursement.

RESULTS

A total of 2252 patients were identified with 8205 total lab test values. Of these, only 4% were abnormal (3% of hemoglobin values, 6% of creatinine values, 3% of potassium of values, and 3% of glucose values), and only 1% were actively intervened upon. The total aggregate cost of the protocolized POD 1 laboratory tests in these years was $64,000 based on Medicare outpatient reimbursement dollars.

CONCLUSIONS

Routine POD 1 lab tests after elective colorectal surgery are rarely abnormal, and they even less frequently require active intervention beyond rechecking. This results in increased resource utilization and cost of care without appreciable impact on clinical care, and is not cost-effective. Protocolized POD 1 laboratory testing should be replaced with clinically-based criteria to trigger serum laboratory investigations.

Evaluation of Routine Postoperative Labs Following Robotic Assisted Partial Nephrectomy in Patients With Normal Preoperative Renal Function

OBJECTIVE

To evaluate predictors of abnormal routine postoperative day 1 (POD1) labs in patients with normal pre-operative renal function following robotic assisted partial nephrectomy (RAPN) and the associated clinical outcomes of these lab results.

METHODS

We analyzed 500 consecutive RAPN from a single surgeon series. Patients with chronic kidney disease (CKD) III or greater were excluded from the study. Three hundred ninty-three RAPN were included in the analysis. Routine POD1 lab tests including hemoglobin (Hgb), creatinine, potassium, and sodium were evaluated to determine rates of abnormal values and rates of clinical intervention. Abnormal Hgb at POD1 was defined as <8 g/dL or ≥3 g/dL decrease from the preoperative (baseline) value. Abnormal sodium (Na) preoperatively and postoperatively was defined as <135 mEq/L or >145 mEq/L. Abnormal potassium (K) was defined preoperatively and POD1 as <3.5 mEq/L or >5 mEq/L.

RESULTS

Of 37.4% (147/393) had one or more abnormal labs at POD1. Of the 101 patients with abnormal Hgb, 15 patients required blood transfusion. Twenty-six patients had abnormal sodium for which two were treated with IV fluids. Twenty-seven patients had potassium abnormalities (12/25 were hypokalemia). Acute kidney injury stage I was seen in 27 patients (6.9%) and stage II in 3 (0.8%). Patients with abnormal labs were more likely to have larger renal mass, higher R.E.N.A.L. scores, intraoperative complications, longer operative times, and higher EBL on multivariate analysis.

CONCLUSION

POD1 serum laboratory tests appear to be necessary following RAPN in patients with normal pre-operative renal function.

Can patients with mild post-operative hyponatraemia following elective arthroplasty be discharged safely? A large-scale service evaluation suggests they can

BACKGROUND

Post-operative hyponatraemia is common following arthroplasty. Clinical hyponatraemia guidelines lack detail on when treatment is necessary, and there is a paucity of literature to guide best practice.

METHODS

Data were collected within retrospective service evaluations over two time periods in a single high throughput joint unit. The hospital's electronic database identified 1000 patients who were admitted electively between February 2012 and June 2013 and again between November 2018 and April 2019 for primary total hip, total knee or uni-compartmental knee arthroplasty. Hyponatraemia and non-hyponatraemia groups were compared. Logistic regression analysis was used to identify independent predictors of post-operative hyponatraemia, length of stay (LOS), re-attendance or re-admission to hospital.

RESULTS

Between 2012-2013 and 2018-2019, 32.1% and 25.7% of patients, respectively, developed post-operative hyponatraemia (serum sodium (s[Na]) ≤135 mmol/L). Those with post-operative hyponatraemia were significantly older, weighed less, were more comorbid and had lower pre-operative sodium. Multivariate analysis showed that increased age, knee surgery and lower pre-operative s[Na] independently predicted post-operative hyponatraemia. Post-operative hyponatraemia did not independently predict LOS, re-attendance or re-admission to hospital, within 90 days, in either cohort.

CONCLUSION

Post-operative hyponatraemia is common and may be a marker of pre-operative vulnerability. In these cohorts, it was not independently associated with LOS, re-attendance or re-admission to hospital. We suggest that otherwise well patients with mild hyponatraemia can be safely discharged earlier than is often the case and may not require extensive investigation. Further examination and research is required to develop a pre-operative approach to predict which patients will develop significant post-operative hyponatraemia.

The role of routine postoperative laboratory tests following hip hemiarthroplasty for an elderly femoral neck fracture

Background

Performing postoperative laboratory tests following joint arthroplasty is a regular practice. However, the role of routine postoperative laboratory tests in primary hip arthroplasty is currently in doubt. This study aimed to assess the role of routine postoperative laboratory tests for femoral neck fractures in elderly patients who underwent hip hemiarthroplasty and to evaluate the risk factors for postoperative laboratory testing abnormalities and related interventions.

Methods

This retrospective study reviewed 735 consecutive patients with femoral neck fractures (FNFs) who underwent hip hemiarthroplasty at a single tertiary academic organization. Patient characteristic features and laboratory testing values were recorded. Logistic regression models were calculated to identify risk factors.

Results

A total of 321 elderly patients (> 75 years of age) were ultimately enrolled for analysis. Abnormal postoperative laboratory tests were found in 265 patients (82.6%). Only a minority of the included patients (7.5%) needed medical intervention to treat postoperative laboratory testing abnormalities. Multivariate logistic regression analysis reported that a higher Charlson comorbidity index (CCI) (P = 0.03), abnormal preoperative haemoglobin level (P < 0.01), higher intraoperative blood loss (P < 0.01) and less frequent tranexamic acid use (P = 0.05) were risk factors for abnormal postoperative laboratory tests. Furthermore, a higher CCI has been identified as a risk factor for patients needing clinical interventions related to laboratory abnormalities.

Conclusions

Because 92.5% of laboratory tests did not influence postoperative management, the authors suggest that routine laboratory tests after hip hemiarthroplasty for FNFs are less instructive for the majority of elderly patients. Nevertheless, for patients with identified risk factors, postoperative laboratory tests are still required to identify the abnormalities that need to be managed.

Re-evaluating the necessity of routine laboratory tests after high tibial osteotomy surgery

BACKGROUND

To assess the utility of routine postoperative laboratory tests for patients undergoing high tibial osteotomy (HTO) surgery.

METHODS

The associations between clinical risk factors and postoperative clinical treatment were analyzed. Additionally, a logistic regression analysis was performed to detect independent risk factors for patients requiring postoperative clinical treatment.

RESULTS

A total of 482 patients with symptomatic isolated medial compartment osteoarthritis from January 2015 to May 2020 were included in the present study and underwent examination by the full set of postoperative laboratory tests within 3 days after HTO surgery. 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 analysis showed that the body mass index (BMI), preoperative hemoglobin level, estimated blood loss and operative duration were independent risk factors for postoperative blood transfusion in patients who underwent HTO surgery, and factors associated with albumin supplementation were female sex and preoperative albumin level. In addition, these results indicated that preoperative potassium was potential risk factor for patients who required potassium supplementation postoperatively.

CONCLUSIONS

Based on the analysis, we conclude that routinely ordering postoperative laboratory tests after HTO surgery is unnecessary. However, for patients with identified risk factors, routine postoperative laboratory tests are still needed.

Prevalence, risk factors, and complications associated with hyponatraemia following elective primary hip and knee arthroplasty

Background

Hyponatraemia, defined as a serum sodium [Na] concentration below 135 mmol/L, is common following surgery. As inpatient peri-operative stays shorten, there is a need to recognise pre-operative risk factors for post-operative hyponatraemia and complications associated with a peri-operative drop in Na. This audit aimed to investigate the prevalence of, risk factors for, and complications associated with hyponatraemia following elective primary hip and knee arthroplasty.

Methods

Data were collected within a retrospective audit of inpatient complications and unplanned reattendance or readmission at hospital in consecutive elective primary hip and knee arthroplasty patients in a single high throughput elective primary joint unit. The hospital’s electronic database identified 1000 patients who were admitted electively between February 2012 and June 2013 under the care of a single consultant orthopaedic surgeon for either total hip arthroplasty, total knee arthroplasty, or uni-compartmental knee arthroplasty. Groups were compared using appropriate tests, including chi-square analysis (or Fisher’s exact test), Mann-Whitney U test, Kruskal-Wallis test, and Wilcoxin signed-rank test. Logistic regression analysis was used to determine factors associated with hyponatraemia.

Results

Of the total 1000 patients, 217 (21.7%) developed post-operative hyponatraemia. Of these, 177 (81.6%) had mild (Na 130–134 mmol/L), 37 (17.1%) had moderate (Na 125–129 mmol/L), and 3 (1.4%) had severe (Na < 125 mmol/L) hyponatraemia. In multivariate analysis, age, pre-operative Na, and fasting glucose on day 1 remained significantly associated with having hyponatraemia post-operatively. There were no significant differences in reattendance at emergency departments and/or readmission within 90 days between those who had post-operative hyponatraemia whilst in hospital (39/217 = 18.0%) and those who did not (103/783 = 13.2%), or between those who were discharged with hyponatraemia (18/108 = 16.7%) and those discharged with normal Na (124/880 = 14.1%).

Conclusion

Approximately one fifth of elective joint arthroplasty patients had post-operative hyponatraemia. In these patients, older age, lower pre-operative Na and higher fasting glucose predicted post-operative hyponatraemia. We found no evidence that those discharged with hyponatraemia had more reattendance at emergency departments or readmission to hospital. We suggest that otherwise well patients with mild hyponatraemia can safely be discharged and followed up in the community.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-021-00197-1.

Routine Basic Metabolic Panels Are Not Needed in All Patients After Primary Total Joint Arthroplasty: An Opportunity for Cost Reduction

BACKGROUND

As the incidence of total joint arthroplasty (TJA) increases, identifying methods for cost reduction is essential. Basic metabolic panels (BMPs) are obtained routinely after TJA. We aimed at assessing the prevalence of intervention secondary to abnormal BMPs after primary TJA and at identifying predictors of the need for postoperative BMPs.

METHODS

We reviewed 802 cases (758 patients) of primary lower-extremity TJA performed from January 1 through December 31, 2018, at our tertiary care medical center. Patient characteristics, preoperative and postoperative BMPs, comorbidities, current medications, and in-hospital interventions were recorded. Age-adjusted Charlson Comorbidity Index (AA-CCI) values were calculated. Institutional costs of 1 BMP and of all BMPs not prompting intervention were calculated. We used multiple regression to identify independent predictors of in-hospital interventions secondary to abnormal postoperative BMPs.

RESULTS

Our institutional BMP cost was $36. A total of 1032 postoperative BMPs were ordered; 958 (93%) prompted no intervention. This equated to $34,488 of avoidable BMP costs. We identified 27 cases (3.4%) requiring intervention secondary to abnormal BMPs. Independent predictors of intervention were preoperative renal dysfunction (ie, abnormal creatinine or glomerular filtration rate <60 mL/min) (odds ratio [OR], 7.8; 95% confidence interval [CI], 2.8-22), number of current nephrotoxic medications (OR, 1.9; 95% CI, 1.3-2.9), and AA-CCI value (OR, 1.2; 95% CI, 1.0-1.5).

CONCLUSION

Routine postoperative BMPs are unwarranted for most patients undergoing primary TJA. Testing may be reserved for those with renal dysfunction, those taking multiple nephrotoxic medications, or those with a high AA-CCI value.

Usefulness of Perioperative Laboratory Tests in Total Hip and Knee Arthroplasty: Are They Necessary for All Patients?

Background

Laboratory studies are routinely obtained preoperatively and postoperatively for total hip arthroplasty (THA) and total knee arthroplasty (TKA). This study evaluates the necessity of routine, perioperative laboratory tests and identifies risk factors for laboratory-associated interventions.

Methods

This retrospective review evaluated 967 consecutive patients scheduled for primary, unilateral TKAs (n = 593) or THAs (n = 374) over an 18-month period at a single institution. Preoperative prothrombin time (PT) and International Normalized Ratio (INR), complete blood count (CBC), complete metabolic panel (CMP), and postoperative CBC and basic metabolic panel (BMP) were recorded along with any laboratory-associated intervention. Patient demographics and comorbidities identified risk factors for abnormal or actionable laboratory studies.

Results

Preoperatively, the actionable rates for PT/INR, CMP, and CBC were 0.3%, 1.4%, and 0.5%, respectively. Vascular, renal, and immunologic diseases were risk factors for an actionable CBC. Risk factors for an actionable CMP include cardiac arrhythmia and diabetes. There were no risk factors for an actionable PT/INR. Postoperatively, only 1.5% of BMPs and 1.5% of CBCs were actionable. Congestive heart failure, renal disease vascular disease, or history of cancer (P = .030) were risk factors for an actionable CBC. There were no risk factors for an actionable BMP. Patients with an abnormal preoperative lab were 2.4 times more likely to have an actionable postoperative lab. Patients with an actionable preoperative lab were 11.3 times more likely to have an actionable postoperative lab.

Conclusion

Routine preoperative and postoperative labs may not be necessary on all patients undergoing a TKA or THA. Comorbid risk factors and abnormal or actionable preoperative CMPs and CBCs can help determine the usefulness of postoperative laboratory assessments.

Routine postoperative blood tests in all patients undergoing Total Hip Arthroplasty as part of an enhanced recovery pathway: Are they necessary?

INTRODUCTION

The increasing demand for Total Hip replacement (THR)/Total Hip Arthroplasty (THA) continues to place significant financial pressure on the National Health Service (NHS). Many institutions undertake post-operative blood tests routinely in this group of patients. The aim of this study was to identify if such routine blood tests (Full Blood Count (FBC) and Urea and Electrolytes(U&Es)) are required in all THR patients post-operatively.

METHODS

Single institute, Multi-surgeon, retrospective observational study of consecutive patients who underwent primary elective THR done from Jan 2014 to Dec 2018.Post-operative blood tests and medical records were reviewed to identify derangement in haemoglobin (Hb) level and renal function requiring clinical intervention.

RESULTS

Over the period of 4 years, 353 patients underwent elective THR with mean age of 70 years (range: 42-90). There were 203 Males and 150 Females. Mean pre-operative Hb was 134.7 g/l. Mean post-operative drop in Hb was 22.3 g/l. None of the patients in ASA grade 1 and 2 with age ≤70 years required blood transfusion post operatively.6.4% of patients (n = 18/280) with an ASA of 1-2 had postoperative blood results requiring intervention of which only four (1.2%) were ≤70 years of age compared to 17.8% of patients (n = 14/73) with ASA 3-4.Overall none of the patients in ASA grade 1 and 2 with age ≤70 years required blood transfusion post operatively nor had electrolyte disturbance. 1.2% had deranged renal function that needed minor clinical intervention.

CONCLUSION

Routine post-operative blood analyses may not required for all patients undergoing THA. Young and healthier patients seldom have significant abnormalities on routine post-operative blood analyses which requires clinical intervention.

Cost of investigations during the acute hospital stay following total hip or knee arthroplasty, by complication status

Background

Total hip and total knee arthroplasties are among the most common types of surgery performed in Australia today and are effective treatments for severe osteoarthritis. However, the increasing financial burden on the health system owing to the increasing rates of surgery has led to a growing interest in improving the cost-effectiveness and safety of arthroplasty care. This study was designed to quantify the association between post-operative complications, a major cost driver, and the cost of investigations following total hip or knee arthroplasty.

Methods

This is a prospective cohort study of consecutive patients undergoing primary total hip or knee arthroplasty at an Australian public hospital. We measured the number and cost of imaging and pathology tests performed during the acute hospital stay and used linear regression to quantify the association between complication status and investigation costs.

Results

Five hundred patients were included in the analysis. On average, those with complications received more tests, and more expensive tests. The mean combined cost of imaging and pathology tests in patients with no complications was AU$ 187 (SD: 12.0). In comparison, patients with minor complications had a mean additional cost of AU$ 270 (SD: 31.0), and those with major complications had a mean additional cost of AU$ 493 (SD: 54.2) (p < 0.001).

Conclusions

In patients undergoing hip or knee arthroplasty, investigation costs are substantially greater in the presence of either minor or major complications. With growing volumes of total hip and total knee arthroplasties, a potential focus of future research could include optimising investigation practices for patients with and without complications.

The necessity of routine postoperative laboratory tests after total hip arthroplasty for hip fracture in a semi-urgent clinical setting

Background

Recent studies suggest that routine postoperative laboratory tests are not necessary after primary elective total hip arthroplasty (THA). This study aims to evaluate the utility of routine postoperative laboratory tests in patients undergoing THA for hip fracture in a semi-urgent clinical setting.

Materials and methods

This retrospective study included 213 consecutive patients who underwent primary unilateral THA for hip fractures. Patient demographics, clinical information, and laboratory tests were obtained from the electronic medical record system. Multivariate logistic regression analysis was performed to identify risk factors associated with abnormal laboratory test-related interventions.

Results

A total of 207 patients (97.18%) had abnormal postoperative laboratory results, which were mainly due to anemia (190/213, 89.20%) and hypoalbuminemia (154/213, 72.30%). Overall, 54 patients (25.35%) underwent a clinical intervention, 18 patients received blood transfusion, and 42 patients received albumin supplementation. Factors associated with blood transfusion were long operative time and low preoperative hemoglobin levels. Factors associated with albumin supplementation were long operative time and low preoperative albumin levels. Of the 33 patients with abnormal postoperative creatinine levels, 7 patients underwent a clinical intervention. For electrolyte abnormalities, sodium supplementation was not given for hyponatremia, three patients received potassium supplementation, and one patient received calcium supplementation.

Conclusions

This study demonstrated a high incidence of abnormal postoperative laboratory tests and a significant clinical intervention rate in patients who underwent THA for hip fracture in a semi-urgent clinical setting, which indicates that routine laboratory tests after THA for hip fracture are still necessary for patients with certain risk factors.

Level of Evidence

Level III.

Trial registration Clinical trial registry number ChiCTR1900020690.

"Outpatient"-Same-calendar-day Discharge Hip and Knee Arthroplasty

As the length of stay for hip and knee arthroplasty has decreased over the years, "outpatient," or same-calendar-day discharge has become increasingly common. Outpatient arthroplasty offers several possible benefits over traditional inpatient arthroplasty, including potential for cost reductions, faster rehabilitation, improved patient satisfaction, and reduced reliance on hospital resources. Despite these possible benefits, concerns remain over feasibility and patient safety. To date, multiple studies have demonstrated that, for select patients, "outpatient" hip and knee arthroplasty can be safe and effective and yield complication and readmission rates similar to inpatient procedures at potentially significant cost savings. Successful outpatient pathways have emphasized careful patient selection, detailed patient education, enlistment of strong social support, utilization of multimodal analgesia and strong "episode ownership," and involvement on behalf of the surgical team. As outpatient hip and knee arthroplasty becomes increasingly common, continued investigation into all aspects of the surgical episode is warranted.

Are Routine Postoperative Laboratory Tests Necessary After Primary Total Hip Arthroplasty?

BACKGROUND

Recently, the practice of ordering routine postoperative laboratory tests in primary total hip arthroplasty (THA) has been challenged. This study aimed to evaluate the utility of routine postoperative laboratory tests after primary elective THA in an Asian population and identify the risk factors associated with abnormal postoperative laboratory test-related intervention.

METHODS

We retrospectively reviewed 395 consecutive patients who underwent primary elective THA at a single tertiary academic center. Patient clinical information and laboratory test results were collected for analysis.

RESULTS

A total of 349 (88.4%) patients had abnormal postoperative laboratory test results; most patients had anemia and hypoalbuminemia. Twenty-seven (6.8%) patients received clinical intervention. Of the 307 (77.7%) patients with postoperative anemia, 7 patients received blood transfusion. Factors associated with transfusion were female gender, low body mass index, long operation time, and low preoperative hemoglobin levels. Of the 149 (37.7%) patients with postoperative hypoalbuminemia, 16 received albumin supplementation. Factors associated with albumin supplementation were female gender, long operation time, and low preoperative albumin levels. Although 36 patients had abnormal postoperative creatinine, only 1 patient required specialist consultation. For electrolyte abnormalities, hyponatremia was noted; however, no patient received sodium supplementation. Moreover, 14 patients developed hypokalemia, of which 6 required potassium supplementation; 163 patients had hypocalcemia, of which 2 received calcium supplementation.

CONCLUSION

Routine laboratory tests after primary elective THA are unnecessary for most of the patients in modern clinical practice. However, for those with identified risk factors, postoperative laboratory tests still should be performed.

Routine postoperative laboratory tests are unnecessary after primary reverse shoulder arthroplasty

BACKGROUND

Obtaining postoperative laboratory studies after primary reverse shoulder arthroplasty (RSA) is a common practice. However, justification of this practice remains unclear. This study assesses the utility of routine postoperative laboratory studies in RSA.

METHODS

The electronic medical records of 369 patients who underwent RSA over 10 years were retrospectively reviewed. A total of 213 patients qualified for analysis. Primary outcomes were intervention related to abnormal laboratory values, length of stay, and 90-day emergency department visits/readmissions. Multivariate logistic regression analysis was performed to identify risk factors associated with abnormal laboratory values and postoperative visits/readmissions.

RESULTS

Of 213 patients analyzed, 188 (88.7%) had abnormal postoperative laboratory values: 69% had an abnormal hemoglobin (Hgb) or hematocrit level, but only 12% underwent interventions. Lower preoperative Hgb was a significant predictor of receiving a transfusion. A significant association existed between abnormal postoperative electrolyte and creatinine levels with lower body mass index (BMI) and higher Charlson Comorbidity Index (CCI). Only 4 patients (1.8%) received non-transfusion related intervention. Emergency department visits were not statistically different between patients with positive or negative laboratory tests (P = .73).

CONCLUSION

Because 87.3% of laboratory studies did not influence patient management, we recommend against routine testing for primary RSA. This study demonstrates that the practice of obtaining routine postoperative laboratory studies is not justified. We recommend selectively obtaining a postoperative basic metabolic profile in patients with increased American Society of Anesthesiologists classification and/or CCI with a lower BMI. We also recommend selectively ordering postoperative complete blood count in patients with a lower preoperative Hgb.

Re-evaluating the utility of routine postoperative laboratory tests after primary total knee arthroplasty

BACKGROUND

While advancements in surgery and reduced complication rates have made total knee arthroplasty (TKA) one of the most successful and cost-effective procedures in orthopaedic surgery, routine postoperative laboratory tests are still being ordered without evidence as to their necessity. With expansion of the bundled payment models, there may exist an opportunity to cut overall costs while maintaining quality of care by eliminating unnecessary interventions. The objective of this study was to examine the utility of routine postoperative laboratory tests in TKA.

METHODS

A retrospective review of 319 TKAs performed at a single institution over a 2-year period was performed. The primary outcomes were the rates of acute blood loss anemia requiring transfusion, acute kidney injury (AKI), electrolyte abnormalities, and 90-day emergency department visits and readmissions. Multivariate logistic regression analysis was also performed to identify the risk factors associated with abnormal laboratory values.

RESULTS

89 patients (27.9%) had abnormal postoperative laboratory results, of which 78% were exclusively due to electrolyte (sodium or potassium) abnormalities. The rates of AKI and blood transfusion were 3.8% and 1% respectively. Factors associated with electrolyte abnormalities were abnormal baseline electrolyte levels (p = 0.002 and = 0.006 for sodium and potassium respectively) and anemia (p = 0.049). Factors associated with blood transfusion were ASA score ≥3, preoperative anemia, and no tranexamic acid use. Factors associated with AKI were chronic kidney disease or having at least two of the following: age >65 years, BMI> 35, ASA score ≥3, diabetes, heart disease, and/or anemia. Laboratory results did not change the course of care in 305 of 319 patients (95.6%). There was no increased risk for 90-days ED visits or readmissions with abnormal laboratory values (p = 0.356).

CONCLUSION

With increasing pressure for cost containment in an era of bundled payment models, the very low rate of laboratory associated interventions suggest that routine postoperative laboratory tests is not justified. Obtaining laboratory after primary, unilateral TKA should be driven by patients' risk factors.

The necessity of routine postoperative laboratory tests in enhanced recovery after surgery for primary hip and knee arthroplasty: A retrospective cohort study protocol

INTRODUCTION

Over the last few decades, the concepts of minimally invasive surgery and enhanced recovery after surgery (ERAS) protocols have been introduced into the field of total joint arthroplasty (TJA), and tranexamic acid (TXA) has been widely used in TJA. Modern-day surgical techniques and perioperative care pathways of TJA have experienced unexpected improvements. Recently, the necessity of the practice of ordering routine postoperative laboratory tests for patients undergoing primary TJA has been challenged, especially in the context of implementation of ERAS protocols in TJA. These studies have consistently suggested that routine postoperative laboratory tests are not necessary in modern-day primary, unilateral total hip arthroplasty (THA) or total knee arthroplasty (TKA), and laboratory tests after surgery should only be obtained for patients with risk factors. However, it remains unclear whether routine postoperative laboratory tests after THA and TKA remains justified in the Chinese patient population. Therefore, we developed this study to address this issue.

METHODS AND ANALYSIS

This retrospective cohort study will include adult patients who underwent primary unilateral THA or TKA and received multimodal perioperative care pathways according to ERAS protocols. The following patient data will be collected from the electronic medical record system: patients' demographics, preoperative and postoperative laboratory values, operation time, intraoperative blood loss, TXA use, tourniquet use, postoperative length of stay, and any medical intervention directly related to abnormal laboratory values. The main study outcomes are the incidence of acute anemia requiring transfusion and incidence of hypoalbuminemia requiring albumin supplementation. The secondary outcomes are the rates of acute kidney injury, incidence of abnormal serum sodium level, incidence of abnormal serum potassium level, and incidence of abnormal serum calcium level. These clinical data will be analyzed to determine the incidence of abnormal postoperative laboratory values following primary unilateral THA and TKA; to clarify the frequency of any medical intervention directly related to abnormal postoperative laboratory values; and to identify risk factors that predispose patients to have abnormal postoperative laboratory results.

STUDY REGISTRATION

Chinese Clinical Trial Registry (http://www.chictr.org.cn): ChiCTR1900020690.

A Novel Risk Calculator Predicts 90-Day Readmission Following Total Joint Arthroplasty

BACKGROUND

A reliable prediction tool for 90-day adverse events not only would provide patients with valuable estimates of their individual risk perioperatively, but would also give health-care systems a method to enable them to anticipate and potentially mitigate postoperative complications. Predictive accuracy, however, has been challenging to achieve. We hypothesized that a broad range of patient and procedure characteristics could adequately predict 90-day readmission after total joint arthroplasty (TJA).

METHODS

The electronic medical records on 10,155 primary unilateral total hip (4,585, 45%) and knee (5,570, 55%) arthroplasties performed at a single institution from June 2013 to January 2018 were retrospectively reviewed. In addition to 90-day readmission status, >50 candidate predictor variables were extracted from these records with use of structured query language (SQL). These variables included a wide variety of preoperative demographic/social factors, intraoperative metrics, postoperative laboratory results, and the 30 standardized Elixhauser comorbidity variables. The patient cohort was randomly divided into derivation (80%) and validation (20%) cohorts, and backward stepwise elimination identified important factors for subsequent inclusion in a multivariable logistic regression model.

RESULTS

Overall, subsequent 90-day readmission was recorded for 503 cases (5.0%), and parameter selection identified 17 variables for inclusion in a multivariable logistic regression model on the basis of their predictive ability. These included 5 preoperative parameters (American Society of Anesthesiologists [ASA] score, age, operatively treated joint, insurance type, and smoking status), duration of surgery, 2 postoperative laboratory results (hemoglobin and blood-urea-nitrogen [BUN] level), and 9 Elixhauser comorbidities. The regression model demonstrated adequate predictive discrimination for 90-day readmission after TJA (area under the curve [AUC]: 0.7047) and was incorporated into static and dynamic nomograms for interactive visualization of patient risk in a clinical or administrative setting.

CONCLUSIONS

A novel risk calculator incorporating a broad range of patient factors adequately predicts the likelihood of 90-day readmission following TJA. Identifying at-risk patients will allow providers to anticipate adverse outcomes and modulate postoperative care accordingly prior to discharge.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Routine Postoperative Laboratory Tests Are Not Necessary After Primary Total Hip Arthroplasty

BACKGROUND

Postoperative laboratory testing has been used routinely for patients undergoing total hip arthroplasty (THA). However, with modern-day improvements in perioperative care pathways, it is unclear whether this practice remains justified. The purpose of this study was to assess the utility of routine postoperative laboratory tests in primary THA.

METHODS

The electronic medical records of 351 patients who underwent primary, unilateral THA between 2015 and 2017 were retrospectively reviewed. The primary outcomes were the rates of acute blood loss anemia requiring transfusion, acute kidney injury (AKI), electrolyte abnormalities, and 90-day emergency department visits or readmissions. Multivariate logistic regression analysis was also performed to identify the risk factors associated with abnormal laboratory values.

RESULTS

Seventy-four patients (21%) had abnormal postoperative laboratory results, of which 82.4% were exclusively due to electrolyte (sodium or potassium) abnormalities. Factors associated with electrolyte abnormalities were abnormal baseline electrolyte levels (P < .001 and P = .013 for sodium and potassium, respectively), diabetes (P = .007), and lack of tranexamic acid use (P < .01). The rates of AKI and blood transfusion were 2.0% and 2.3%, respectively. Factors associated with blood transfusion were higher American Society of Anesthesiologists class and intraoperative blood loss ≥250 mL combined with either preoperative anemia or lack of tranexamic acid use. Factors associated with AKI were higher American Society of Anesthesiologists class and diabetes. Laboratory results did not change the standard course of care in 338 of 351 patients (96%). Abnormal laboratory values were not associated with increased length of stay (P = .228) or emergency department visits/readmissions (P = .21).

CONCLUSION

This study provides evidence that routine postoperative laboratory testing is not necessary in modern-day primary, unilateral THA. Instead, the decision to obtain laboratory tests after surgery should be driven by patients' risk factors.

Should postoperative haemoglobin and potassium levels be checked routinely following blood-conserving primary total joint arthroplasty?

AIMS

Despite declining frequency of blood transfusion and electrolyte supplementation following total joint arthroplasty, postoperative blood analyses are still routinely ordered for these patients. This study aimed to determine the rate of blood transfusion and electrolyte restoration in arthroplasty patients treated with a perioperative blood conservation protocol and to identify risk factors that would predict the need for transfusion and electrolyte supplementation.

PATIENTS AND METHODS

Patients undergoing primary total joint arthroplasty of the hip or knee between July 2016 and February 2017 at a single institution were included in the study. Standard preoperative and postoperative laboratory data were collected and reviewed retrospectively. A uniform blood conservation programme was implemented for all patients. Need for blood transfusion or potassium supplementation was determined through a coordinated decision by the care team. Rates of transfusion and supplementation were observed, and patient risk factors were noted.

RESULTS

The overall rate of blood transfusion was 1.06% in the study population of 1132 total joint arthroplasties performed in 1023 patients. Of the 12 patients requiring transfusion, 11 were female, ten occurred in patients undergoing total hip arthroplasty, and all 12 patients had a preoperative haemoglobin level less than 130 g/l. Operative duration and surgical blood loss were significantly greater in those patients requiring blood transfusion. Nearly all patients requiring transfusion had a history of, or risk factors for, cardiovascular disease. Potassium supplementation was required in 15.5% of the study cohort; 72% of these patients receiving potassium presented with a potassium level less than 4 mmol/l during preoperative testing, while the remaining 28% had a past medical history of either significant anaemia, cardiopulmonary, cardiovascular, or renal diseases that had required substantial medical management.

CONCLUSION

A consistent blood-conserving perioperative strategy effectively minimized need for blood transfusion in total joint arthroplasty patients below previously reported rates in the literature. We suggest that postoperative full blood counts and basic metabolic panels should not routinely be ordered in these patients unless their preoperative haemoglobin and potassium is below 130 g/dl or 4 mmol/l respectively, and they have medical comorbidities.