Timing of Stroke in Patients Undergoing Total Hip Replacement and Matched Controls

Mendelian randomization of stroke risk after total hip and knee replacements

Objective

Previous epidemiological studies have indicated an increased risk of neurovascular diseases in patients following total hip and knee replacements. However, definitive conclusions regarding the increased risk of stroke post-replacement remain elusive. Therefore, we conducted a two-sample Mendelian randomization study to investigate the causal relationship between total hip and knee replacements and stroke.

Methods

We utilized summary data from publicly available genome-wide association studies (GWAS). Data concerning total hip replacements (THR, N = 319,037) and total knee replacements (TKR, N = 252,041) were sourced from the Genetics of Osteoarthritis (GO) Consortium. Stroke-related data were obtained from the International Stroke Genetics Consortium, encompassing any stroke (AS), any ischemic stroke (AIS), large vessel ischemic stroke (LV-IS), cardioembolic ischemic stroke (CE-IS), and small vessel ischemic stroke (SV-IS). Our primary causal inference method was the inverse variance weighted (IVW) approach, supplemented by weighted median and MR-Egger regression as secondary inference methods. We utilized the MR-PRESSO global test for outlier detection, Cochran's Q statistic to assess heterogeneity, and assessed the multiplicity and stability of our findings using p-values from MR-PRESSO and MR-Egger regressions, and the leave-one-out method, respectively.

Results

We identified significant genetic associations between THR and both AS (IVW p = 0.0001, OR = 1.08, 95% CI = 1.04-1.12) and AIS (IVW p = 0.0016, OR = 1.07, 95% CI = 1.03-1.12). Significant associations were also observed between TKR and AS (IVW p = 0.0002, OR = 1.08, 95% CI = 1.04-1.12), as well as AIS (IVW p = 0.0005, OR = 1.15, 95% CI = 1.06-1.24).

Conclusion

Our findings genetically support an increased risk of stroke following total hip and knee replacements. However, further studies are necessary to elucidate the specific mechanisms underlying stroke episodes post-replacement.

Prevention of perioperative stroke in patients undergoing non-cardiac surgery

About 300 million adults undergo non-cardiac surgery annually. Although, in this setting, the incidence of perioperative stroke is low, the absolute number of patients experiencing a stroke is substantial. Furthermore, most patients with this complication will die or end up with severe disability. Covert brain infarctions are more frequent than overt strokes and are associated with postoperative delirium, cognitive decline, and cerebrovascular events at 1 year after surgery. Evidence shows that traditional stroke risk factors including older age, hypertension, and atrial fibrillation are also associated with perioperative stroke; previous stroke is the strongest risk factor for perioperative stroke. Increasing evidence also suggests the pathogenic role of perioperative events, such as hypotension, new atrial fibrillation, paradoxical embolism, and bleeding. Clinicians involved in perioperative care should be aware of this evidence on prevention strategies to improve patient outcomes after non-cardiac surgery.

Timing of adverse events in patients undergoing acute and elective hip arthroplasty surgery: a multicentre cohort study using the Global Trigger Tool

OBJECTIVE

To explore timing in relation to all types of adverse events (AEs), severity and preventability for patients undergoing acute and elective hip arthroplasty.

DESIGN

A multicentre cohort study using retrospective record review with Global Trigger Tool methodology in combination with data from several registers.

SETTING

24 hospitals in 4 major regions of Sweden.

PARTICIPANTS

Patients ≥18 years, undergoing acute or elective total or hemiarthroplasty of the hip, were eligible for inclusion. Reviews of weighted samples of 1998 randomly selected patient records were carried out using Global Trigger Tool methodology. The patients were followed for readmissions up to 90 days postoperatively throughout the whole country.

RESULTS

The cohort consisted of 667 acute and 1331 elective patients. Most AEs occurred perioperatively and postoperatively (n=2093, 99.1%) and after discharge (n=1142, 54.1%). The median time from the day of surgery to the occurrence of AE was 8 days. The median days for different AE types ranged from 0 to 24.5 for acute and 0 to 71 for elective patients and peaked during different time periods. 40.2% of the AEs, both major and minor, occurred within postoperative days 0-5 and 86.9% of the AEs occurred within 30 days. Most of the AEs were deemed to be of major severity (n=1370, 65.5%) or preventable (n=1591, 76%).

CONCLUSIONS

A wide variability was found regarding the timing of different AEs with the majority occurring within 30 days. The timing and preventability varied regarding the severity. Most of the AEs were deemed to be preventable and/or of major severity. To increase patient safety for patients undergoing hip arthroplasty surgery, a better understanding of the multifaceted nature of the timing of AEs in relation to the occurrence of differing AEs is needed.

Impact of Patent Foramen Ovale on Total Knee Arthroplasty Cerebrovascular Accident Perioperative Management

Venous thromboembolism and ischemic stroke are major complications following total knee arthroplasty (TKA) and potentially are associated with a patent foramen ovale (PFO). Although this association has been shown in other surgical disciplines, it has not been demonstrated in patients undergoing TKA. This study was undertaken to determine whether patients with a PFO would have a significantly increased risk of cerebrovascular accident (CVA) following TKA. The Humana national database was used to identify TKA patients who were stratified by the presence of a PFO from 2007 to 2016. Ninety-day follow-up was used for the primary outcome of CVA. Potential confounding comorbidities also were investigated, including age, sex, anticoagulation, insurance type, arrhythmia, valvular disease, peripheral vascular disease, chronic kidney disease, and diabetes mellitus. Of 153,245 TKAs, a total of 2272 patients had strokes; 479 of these patients had a PFO. On multivariable analysis, PFO remained an independent predictor of CVA postoperatively (odds ratio, 3.824; 95% confidence interval, 2.614-5.406; P<.0001). Other significant comorbidities associated with CVA included arrhythmia, chronic kidney disease, diabetes mellitus, peripheral vascular disease, and coronary valve disease. Importantly, low-molecular weight heparin or factor Xa inhibitor administration postoperatively had a negative correlation with stroke (odds ratio, 0.762; 95% confidence interval, 0.663-0.871; P=.0001 and odds ratio, 0.749; 95% confidence interval, 0.628-0.885; P=.0009, respectively). The findings of the multivariable analysis indicate PFO is associated with early postoperative CVA within 90 days following TKA. If known preoperatively, appropriate referral should be made to a cardiologist for PFO management and anticoagulation to reduce the overall risk of stroke. [Orthopedics. 2020;43(3):e151-e158.].

Perioperative covert stroke in patients undergoing non-cardiac surgery (NeuroVISION): a prospective cohort study

BACKGROUND

In non-surgical settings, covert stroke is more common than overt stroke and is associated with cognitive decline. Although overt stroke occurs in less than 1% of adults after non-cardiac surgery and is associated with substantial morbidity, we know little about perioperative covert stroke. Therefore, our primary aim was to investigate the relationship between perioperative covert stroke (ie, an acute brain infarct detected on an MRI after non-cardiac surgery in a patient with no clinical stroke symptoms) and cognitive decline 1 year after surgery.

METHODS

NeuroVISION was a prospective cohort study done in 12 academic centres in nine countries, in which we assessed patients aged 65 years or older who underwent inpatient, elective, non-cardiac surgery and had brain MRI after surgery. Two independent neuroradiology experts, masked to clinical data, assessed each MRI for acute brain infarction. Using multivariable regression, we explored the association between covert stroke and the primary outcome of cognitive decline, defined as a decrease of 2 points or more on the Montreal Cognitive Assessment from preoperative baseline to 1-year follow-up. Patients, health-care providers, and outcome adjudicators were masked to MRI results.

FINDINGS

Between March 24, 2014, and July 21, 2017, of 1114 participants recruited to the study, 78 (7%; 95% CI 6-9) had a perioperative covert stroke. Among the patients who completed the 1-year follow-up, cognitive decline 1 year after surgery occurred in 29 (42%) of 69 participants who had a perioperative covert stroke and in 274 (29%) of 932 participants who did not have a perioperative covert stroke (adjusted odds ratio 1·98, 95% CI 1·22-3·20, absolute risk increase 13%; p=0·0055). Covert stroke was also associated with an increased risk of perioperative delirium (hazard ratio [HR] 2·24, 95% CI 1·06-4·73, absolute risk increase 6%; p=0·030) and overt stroke or transient ischaemic attack at 1-year follow-up (HR 4·13, 1·14-14·99, absolute risk increase 3%; p=0·019).

INTERPRETATION

Perioperative covert stroke is associated with an increased risk of cognitive decline 1 year after non-cardiac surgery, and perioperative covert stroke occurred in one in 14 patients aged 65 years and older undergoing non-cardiac surgery. Research is needed to establish prevention and management strategies for perioperative covert stroke.

FUNDING

Canadian Institutes of Health Research; The Ontario Strategy for Patient Oriented Research support unit; The Ontario Ministry of Health and Long-Term Care; Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region, China; and The Neurological Foundation of New Zealand.

Incidence and Risk Factors for Stroke in Fast-Track Hip and Knee Arthroplasty-A Clinical Registry Study of 24,862 Procedures

BACKGROUND

Postoperative stroke is a severe complication with a reported 30-day incidence of 0.4%-0.6% after total hip (THA) and knee arthroplasty (TKA). However, most data are based on diagnostic codes and with limited details on perioperative care, including the use of fast-track protocols. We investigated the incidence of and preoperative and postoperative factors for stroke after fast-track THA/TKA.

METHODS

We used an observational study design of elective fast-track THA/TKA patients with prospective collection of comorbidity and complete 90-day follow-up. Medical records were evaluated for events potentially disposing to stroke. Identification of relevant preoperative risk factors was done by multivariable logistic regression. Incidence of stroke was compared with a Danish background population.

RESULTS

Of 24,862 procedures with a median length of stay of 2 (interquartile range, 2-3) days, we found 27 (0.11%; 95% confidence interval [CI], 0.08%-0.16%) and 43 strokes (0.17%, 95% CI, 0.13%-0.23%) ≤30 and ≤90 days after surgery, respectively. Preoperative risk factors for stroke ≤30 days were age ≥ 85 years (odds ratio [OR], 4.3; 95% CI, 1.1-16.3) and anticoagulant treatment (OR, 3.1; 95% CI, 1.2-7.9). Preoperative anemia was near significant (OR, 2.1; 95% CI, 0.98-4.6, P = .055). Eight strokes ≤30 days were preceded by a cardiovascular event within the second postoperative day. Incidence of stroke after postoperative day 30 was similar to a Danish background population.

CONCLUSION

Risk of postoperative stroke in fast-track THA and TKA was low but may be further reduced with increased focus on avoiding perioperative cardiovascular events and in patients with preoperative anticoagulants or anemia.

Risk of ischemic stroke after discharge from inpatient surgery: Does the type of surgery matter?

OBJECTIVE

Stroke is a well-known and devastating complication during the perioperative period. However, detailed stroke risk profiles within 90 days in patients discharged without stroke after inpatient surgery are not fully understood. Using the case-crossover design, we aimed to evaluate the risk of ischemic stroke in these patients.

METHODS

We included adult patients with the first hospitalization for ischemic stroke between 2011 and 2012 from 23 million enrollees in the National Health Insurance Research Database. Admission date of the hospitalization was defined as the case day and exactly 365 days before the admission date as the control day. The exposure was the last hospitalization for surgery within 1-30, 31-60, or 61-90 days (case period) before the case day or similar time intervals (control period) before the control day. Surgical types were grouped based on the International Classification of Diseases procedure codes. We performed conditional logistic regression adjusting for time-varying variables to determine the relationship between surgery and subsequent stroke, and case-time-control analyses to examine whether the results were confounded by the time-trend in surgery.

RESULTS

A total of 56596 adult patients (41% female, mean age 69 years) comprised the study population. After adjustment was made for confounding variables, an association between stroke and prior inpatient surgery within 30 days was observed (adjusted odds ratio 1.44; 95% confidence interval 1.29-1.61). Cardiothoracic, vascular, digestive surgery, and musculoskeletal surgery within 30 days independently predicted ischemic stroke in the case-crossover analysis. In the case-time-control analysis, inpatient surgery remained an independent risk factor for ischemic stroke, whereas only cardiothoracic, vascular, and digestive surgery independently predicted ischemic stroke.

CONCLUSIONS

Surgery as a whole independently increased the risk of ischemic stroke within 30 days. Among various types of surgery, cardiothoracic, vascular, and digestive surgery significantly increased the risk of ischemic stroke.

Accuracy and utility of using administrative healthcare databases to identify people with epilepsy: a protocol for a systematic review and meta-analysis

INTRODUCTION

In an increasingly digital age for healthcare around the world, administrative data have become rich and accessible tools for potentially identifying and monitoring population trends in diseases including epilepsy. However, it remains unclear (1) how accurate administrative data are at identifying epilepsy within a population and (2) the optimal algorithms needed for administrative data to correctly identify people with epilepsy within a population. To address this knowledge gap, we will conduct a novel systematic review of all identified studies validating administrative healthcare data in epilepsy identification. We provide here a protocol that will outline the methods and analyses planned for the systematic review.

METHODS AND ANALYSIS

The systematic review described in this protocol will be conducted to follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE and Embase will be searched for studies validating administrative data in epilepsy published from 1975 to current (01 June 2018). Included studies will validate the International Classification of Disease (ICD), Ninth Revision (ICD-9) onwards (ie, ICD-9 code 345 and ICD-10 codes G40-G41) as well as other non-ICD disease classification systems used, such as Read Codes in the UK. The primary outcome will be providing pooled estimates of accuracy for identifying epilepsy within the administrative databases validated using sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curves. Heterogeneity will be assessed using the I² statistic and descriptive analyses used where this is present. The secondary outcome will be the optimal administrative data algorithms for correctly identifying epilepsy. These will be identified using multivariable logistic regression models. 95% confidence intervals will be quoted throughout. We will make an assessment of risk of bias, quality of evidence, and completeness of reporting for included studies.

ETHICS AND DISSEMINATION

Ethical approval is not required as primary data will not be collected. Results will be disseminated in peer-reviewed journals, conference presentations and in press releases.

PROSPERO REGISTRATION

CRD42017081212.

Osteoarthritis, cerebrovascular dysfunction and the common denominator of inflammation: a narrative review

OBJECTIVE

Population-based cohort studies suggest an association between osteoarthritis (OA) and cerebrovascular disease, yet the mechanisms underlying vascular comorbidities in OA remain unclear. The purpose of this narrative review is to discuss the literature examining inflammation in OA with a focus on physiological mechanisms, and whether overlapping mechanisms exist in cerebrovascular dysfunction.

METHOD

A literature search was conducted in PubMed using combinations of search terms: osteoarthritis, cerebrovascular (disease/dysfunction/risk), cardiovascular (disease/dysfunction/risk), aging/ageing, inflammation, inflammatory mediators, cytokine, c-reactive protein, interleukin, advanced glycation end-products, metabolic syndrome, reactive oxidative species, cognitive impairment, (vascular-related) dementia, small cerebral vessel disease, endothelial function, blood-brain barrier, gender/sex, hypertension, peripheral vascular health, and physical activity. Reference lists of identified articles were also researched manually.

RESULTS

Overlapping inflammatory factors that may contribute to onset and progression of both OA and cerebrovascular dysfunction are presented. We describe oxidative mechanisms involving pro-inflammatory cytokines and oxidative species, advanced glycation end-products, sex hormones, microvascular dysfunction and osteoprotegerin, and their specific roles in potentially contributing to OA and cerebrovascular dysfunction.

CONCLUSION

Synthesis of the current literature suggests future investigations may benefit from directly testing cerebrovascular hemodynamics and cognitive function in individuals with or at risk of OA to elucidate common physiological mechanisms.

Risks of Cardiovascular Adverse Events and Death in Patients with Previous Stroke Undergoing Emergency Noncardiac, Nonintracranial Surgery

Background

The outcomes of emergent noncardiac, nonintracranial surgery in patients with previous stroke remain unknown.

Methods

All emergency surgeries performed in Denmark (2005 to 2011) were analyzed according to time elapsed between previous ischemic stroke and surgery. The risks of 30-day mortality and major adverse cardiovascular events were estimated as odds ratios (ORs) and 95% CIs using adjusted logistic regression models in a priori defined groups (reference was no previous stroke). In patients undergoing surgery immediately (within 1 to 3 days) or early after stroke (within 4 to 14 days), propensity-score matching was performed.

Results

Of 146,694 nonvascular surgeries (composing 98% of all emergency surgeries), 5.3% had previous stroke (mean age, 75 yr [SD = 13]; 53% women, 50% major orthopedic surgery). Antithrombotic treatment and atrial fibrillation were more frequent and general anesthesia less frequent in patients with previous stroke (all P &lt; 0.001). Risks of major adverse cardiovascular events and mortality were high for patients with stroke less than 3 months (20.7 and 16.4% events; OR = 4.71 [95% CI, 4.18 to 5.32] and 1.65 [95% CI, 1.45 to 1.88]), and remained increased for stroke within 3 to 9 months (10.3 and 12.3%; OR = 1.93 [95% CI, 1.55 to 2.40] and 1.20 [95% CI, 0.98 to 1.47]) and stroke more than 9 months (8.8 and 11.7%; OR = 1.62 [95% CI, 1.43 to 1.84] and 1.20 [95% CI, 1.08 to 1.34]) compared with no previous stroke (2.3 and 4.8% events). Major adverse cardiovascular events were significantly lower in 323 patients undergoing immediate surgery (21%) compared with 323 successfully propensity-matched early surgery patients (29%; P = 0.029).

Conclusions

Adverse cardiovascular outcomes and mortality were greatly increased among patients with recent stroke. However, events were higher 4 to 14 days after stroke compared with 1 to 3 days after stroke.

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Background

Although hip and knee arthroplasties are considered to be common elective cost-effective operations, up to one-quarter of patients are not satisfied with the operation. A number of risk factors for implant failure are known, but little is known about the predictors of patient-reported outcomes.

Objectives

(1) Describe current and future needs for lower limb arthroplasties in the UK; (2) describe important risk factors for poor surgery outcomes and combine them to produce predictive tools (for hip and knee separately) for poor outcomes; (3) produce a Markov model to enable a detailed health economic analysis of hip/knee arthroplasty, and for implementing the predictive tool; and (4) test the practicality of the prediction tools in a pragmatic prospective cohort of lower limb arthroplasty.

Design

The programme was arranged into four work packages. The first three work packages used the data from large existing data sets such as Clinical Practice Research Datalink, Hospital Episode Statistics and the National Joint Registry. Work package 4 established a pragmatic cohort of lower limb arthroplasty to test the practicality of the predictive tools developed within the programme.

Results

The estimated number of total knee replacements (TKRs) and total hip replacements (THRs) performed in the UK in 2015 was 85,019 and 72,418, respectively. Between 1991 and 2006, the estimated age-standardised rates (per 100,000 person-years) for a THR increased from 60.3 to 144.6 for women and from 35.8 to 88.6 for men. The rates for TKR increased from 42.5 to 138.7 for women and from 28.7 to 99.4 for men. The strongest predictors for poor outcomes were preoperative pain/function scores, deprivation, age, mental health score and radiographic variable pattern of joint space narrowing. We found a weak association between body mass index (BMI) and outcomes; however, increased BMI did increase the risk of revision surgery (a 5-kg/m2rise in BMI increased THR revision risk by 10.4% and TKR revision risk by 7.7%). We also confirmed that osteoarthritis (OA) severity and migration pattern of the hip predicted patient-reported outcome measures. The hip predictive tool that we developed performed well, with a correctedR2of 23.1% and had good calibration, with only slight overestimation of Oxford Hip Score in the lowest decile of outcome. The knee tool developed performed less well, with a correctedR2of 20.2%; however, it had good calibration. The analysis was restricted by the relatively limited number of variables available in the extant data sets, something that could be addressed in future studies. We found that the use of bisphosphonates reduced the risk of revision knee and hip surgery by 46%. Hormone replacement therapy reduced the risk by 38%, if used for at least 6 months postoperatively. We found that an increased risk of postoperative fracture was prevented by bisphosphonate use. This result, being observational in nature, will require confirmation in a randomised controlled trial. The Markov model distinguished between outcome categories following primary and revision procedures. The resulting outcome prediction tool for THR and TKR reduced the number and proportion of unsatisfactory outcomes after the operation, saving NHS resources in the process. The highest savings per quality-adjusted life-year (QALY) forgone were reported from the oldest patient subgroups (men and women aged ≥ 80 years), with a reported incremental cost-effectiveness ratio of around £1200 saved per QALY forgone for THRs. In the prospective cohort of arthroplasty, the performance of the knee model was modest (R2 = 0.14) and that of the hip model poor (R2 = 0.04). However, the addition of the radiographic OA variable improved the performance of the hip model (R2 = 0.125 vs. 0.110) and high-sensitivity C-reactive protein improved the performance of the knee model (R2 = 0.230 vs. 0.216). These data will ideally need replication in an external cohort of a similar design. The data are not necessarily applicable to other health systems or countries.

Conclusion

The number of total hip and knee replacements will increase in the next decade. High BMI, although clinically insignificant, is associated with an increased risk of revision surgery and postoperative complications. Preoperative pain/function, the pattern of joint space narrowing, deprivation index and level of education were found to be the strongest predictors for THR. Bisphosphonates and hormone therapy proved to be beneficial for patients undergoing lower limb replacement. The addition of new predictors collected from the prospective cohort of arthroplasty slightly improved the performance of the predictive tools, suggesting that the potential improvements in both tools can be achieved using the plethora of extra variables from the validation cohort. Although currently it would not be cost-effective to implement the predictive tools in a health-care setting, we feel that the addition of extensive risk factors will improve the performances of the predictive tools as well as the Markov model, and will prove to be beneficial in terms of cost-effectiveness. Future analyses are under way and awaiting more promising provisional results.

Future work

Further research should focus on defining and predicting the most important outcome to the patient.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Incidence, Risk Factors, and Clinical Implications of Pneumonia Following Total Hip and Knee Arthroplasty

BACKGROUND

The purpose of this study is to determine the incidence, risk factors, and clinical implications of pneumonia following total joint arthroplasty (TJA).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was used to conduct a retrospective cohort study of patients undergoing TJA. Independent risk factors for the development of pneumonia within 30 days of TJA were identified using multivariate regression. Mortality and readmission rates were compared between patients who did and did not develop pneumonia. Multivariate regression was used to adjust for all demographic, comorbidity, and procedural characteristics.

RESULTS

In total, 171,200 patients met inclusion criteria, of whom 66,493 (38.8%) underwent THA and 104,707 (61.2%) underwent TKA. Of the 171,200 patients, 590 developed pneumonia, yielding a rate of 0.34% (95% confidence interval = 0.32%-0.37%). Independent risk factors for pneumonia were chronic obstructive pulmonary disease, diabetes mellitus, greater age (most notably ≥80 years), dyspnea on exertion, dependent functional status, lower body mass index, hypertension, current smoker status, and male sex. The subset of patients who developed pneumonia following discharge had a higher readmission rate (82.1% vs 3.4%, adjusted relative risk [RR] = 16.6, P < .001) and a higher mortality rate (3.7% vs 0.1%, adjusted RR = 19.4, P < .001). Among 124 total mortalities, 22 (17.7%) occurred in patients who had developed pneumonia.

CONCLUSION

Pneumonia is a serious complication following TJA that occurs in approximately 1 in 300 patients. Approximately 4 in 5 patients who develop pneumonia are subsequently readmitted, and approximately 1 in 25 die. Given the serious implications of this complication, evidence-based pneumonia prevention programs including oral hygiene with chlorhexidine, sitting upright for meals, elevation of the head of the bed to at least 30°, aggressive incentive spirometry, and early ambulation should be considered for patients at greatest risk.

Risk of Ischemic Stroke and Transient Ischemic Attack Is Increased up to 90 Days after Non-Carotid and Non-Cardiac Surgery

Background: The risk of stroke after cardiac and carotid surgery is well established. In contrast, stroke risk in association with non-cardiac and non-carotid surgery and its time course are insufficiently known. We investigated the prevalence of recent and planned surgery among patients with stroke and transient ischemic attack (TIA), time dependency of stroke risk, stroke etiology, and interruption of antithrombotic medication in association with surgery. Methods: Data on type and date of surgery and similar interventions within the last year or planned for the next 2 weeks were anonymously collected together with demographic data, vascular risk factors, stroke severity, handicap before stroke and stroke etiology within a state-wide, mandatory, hospital-based acute stroke care quality monitoring project (Rhineland-Palatinate, Germany) for 1 year (2010). Results: Non-carotid and non-cardiothoracic surgery was reported as performed within 1 year before the index event or as planned for the next 2 weeks thereafter in 532 out of 12,120 patients with ischemic stroke/TIA (4.4%). Compared to 91-365 days before stroke/TIA as reference period, risk of cerebral ischemia (per day analysis) was increased for surgery within 61-90 days before ischemia (rate ratio 2.0, 95% CI 1.5-2.8) and continuously increased along shorter intervals between stroke and surgery (31-60 days: rate ratio 3.6, 95% CI 2.9-4.5; 15-30 days: rate ratio 8.2, 95% CI 6.7-10.1; 8-14 days: rate ratio 13.2, 95% CI 10.3-16.8; 4-7 days: rate ratio 16.5, 95% CI 12.2-22.1) peaking at an interval of 1-3 days before ischemia (rate ratio 34.0, 95% CI 26.9-42.8). On the day of surgery, rate ratio was 14.8 (95% CI 7.8-27.9) and for planned surgery it was 2.7 (95% CI 1.8-4.0). Results were similar for first-ever and for recurrent ischemic stroke. Perioperative stroke/TIA was positively associated with atrial fibrillation and cardioembolic stroke etiology, higher mortality, more severe neurological deficits at discharge, and longer hospital stay; and it was inversely associated with microangiopathic etiology and discharge at home. In 34.5% of patients with recent/planned surgery, prior antithrombotic or anticoagulant medication had been interrupted. Conclusions: Recent or planned surgery imposes a considerable short-term stroke risk particularly by cardioembolism with cessation of medication as an important contributor. Stroke after surgery is associated with poor outcome and high mortality. Better strategies to reduce the burden of perioperative stroke are urgently required.

First-ever stroke following hip replacement surgeries: a large population-based survey

OBJECTIVE

This study was designed to determine the prevalence, subtypes and risk factors of first-ever stroke following hip replacement (HR) in a large population of Taiwan.

METHODS

Using the National Health Insurance system of Taiwan, we identified patients undergoing HR from 2000 to 2011 and randomly selected 4 : 1 age- and sex-matched controls for each HR patients. The index date for HR patients was defined the date for HR. All study subjects were followed from the index date until stroke occurred at admission. T-test and chi-square test were used for continuous and categorical variables, respectively. The hazard ratios of risk factors were determined with Cox proportional hazard regression model.

RESULTS

A total of 3604 HR patients and 14 394 controls were enrolled. In comparison with controls, patients undergoing HR had a significantly higher incidence of comorbidities (i.e. atrial fibrillation, hypertension, diabetes) and consumed more medications (i.e. antihypertension, antidiabetes, nonsteroid anti-inflammatory drugs and anticoagulants) before surgery. The HR patients had a significant higher incidence of first-ever stroke, especially for those aged over 65. (Hazard ratio: 1·33, 95% confidence interval: 1·12-1·58) The significantly higher risk for first-ever stroke occurred within 3 months and ≥ 1 year after HR. The incidence rate of ischaemic stroke is about five times than that of haemorrhagic stroke.

CONCLUSION

Our study identifies multiple risk factors that cause cerebrovascular complications after HR, which is vital in creating treatment plans to prevent for said problems.

Statins and Risk of Lower Limb Revision Surgery: The Influence of Differences in Study Design Using Electronic Health Records From the United Kingdom and Denmark

Previous observational studies on statins have shown variable results based on the methodology used. Our objective was to study the association between statins and orthopedic implant failure and to explore the influence of methodological differences in study design. Our study base consisted of patients with a primary total joint replacement in Denmark and the United Kingdom (n = 189,286; 1987–2012). We used 4 study designs: 1) case-control (each patient with revision surgery matched to 4 controls), 2) time-dependent cohort (postoperative statin use as a time-varying exposure variable), 3) immortal time cohort (misclassifying the time postoperatively before statin use), and 4) time-exclusion cohort (excluding the time postoperatively before statin use). Cox proportional hazards models and logistic regression were used to estimate incidence rate ratios. In the time-dependent cohort design, statin use was associated with a decreased risk of revision surgery (adjusted incidence rate ratio (IRR) = 0.90, 95% confidence interval (CI): 0.85, 0.96), which was similar to our case-control results (IRR = 0.87, 95% CI: 0.81, 0.93). In contrast, both time-fixed cohort designs yielded substantially lower risk estimates (IRR = 0.36 (95% CI: 0.34, 0.38) and IRR = 0.65 (95% CI: 0.63, 0.68), respectively). We discourage the use of time-fixed cohort studies, which may falsely suggest protective effects. The simple choice of how to classify exposure can substantially change results from biologically plausible to implausible.

What are the Risk Factors for Cerebrovascular Accidents After Elective Orthopaedic Surgery?

BACKGROUND

Perioperative cerebrovascular accidents (CVAs) are one of the leading causes of patient morbidity, mortality, and medical costs. However, little is known regarding the rates of these events and risk factors for CVA after elective orthopaedic surgery.

QUESTIONS/PURPOSES

Our goals were to (1) establish the national, baseline proportion of patients experiencing a 30-day CVA and the timing of CVA; and (2) determine independent risk factors for 30-day CVA rates after common elective orthopaedic procedures.

METHODS

Patients undergoing elective TKA, THA, posterior or posterolateral lumbar fusion, anterior cervical discectomy and fusion, and total shoulder arthroplasty, from 2006 to 2012, were identified from the American College of Surgeons National Surgical Quality Improvement Program(®) database. A total of 42,150 patients met inclusion criteria. Thirty-day CVA rates were recorded for each procedure, and patients were assessed for characteristics associated with CVA through univariate analysis. Multivariate regression models were created to identify independent risk factors for CVA.

RESULTS

A total of 55 (0.13%) patients experienced a CVA within 30 days of the procedure, occurring a median of 2 days after surgery (range, 1-30 days) with 0.08% of patients experiencing a CVA after TKA, 0.15% after THA, 0.00% after single-level anterior cervical discectomy and fusion, 0.38% after multilevel anterior cervical discectomy and fusions, 0.20% after single-level posterior or posterolateral lumbar fusion, 0.70% after multilevel posterior or posterolateral lumbar fusion, and 0.22% after total shoulder arthroplasty. Independent risk factors for CVA included age of 75 years or older (odds ratio [OR], 2.50; 95% CI, 1.44-4.35; p = 0.001), insulin-dependent diabetes mellitus (OR, 3.08; CI, 1.47-6.45; p = 0.003), hypertension (OR, 2.71; CI, 1.19-6.13; p = 0.017), history of transient ischemic attack (OR, 2.83; CI, 1.24-6.45; p = 0.013), dyspnea (OR, 2.51; CI, 1.30-4.86; p = 0.006), chronic obstructive pulmonary disease (OR, 2.33; CI, 1.06-5.13; p = 0.036), and operative time of 180 minutes or greater (OR, 3.25; CI 1.60-6.60; p = 0.001).

CONCLUSIONS

Numerous nonmodifiable patient comorbidities and increased operative time were associated with CVA after elective orthopaedic procedures. However, the American College of Surgeons National Surgical Quality Improvement Program(®) database does not code for cardiac arrhythmia or atrial fibrillation, which other studies have suggested may be important predictor variables; those may be important risk factors, although we were unable to evaluate them in our study. Surgeons should counsel patients with these risk factors and limit their operative time to reduce the risk of these adverse events, and future studies should examine other patient characteristics such as arrhythmia and noncoronary heart disease and assess the role of pharmacologic prophylaxis in patients with these risk factors.

LEVEL OF EVIDENCE

Level III, prognostic study.

Cerebral fat embolism: Use of MR spectroscopy for accurate diagnosis

Cerebral fat embolism (CFE) is an uncommon but serious complication following orthopedic procedures. It usually presents with altered mental status, and can be a part of fat embolism syndrome (FES) if associated with cutaneous and respiratory manifestations. Because of the presence of other common factors affecting the mental status, particularly in the postoperative period, the diagnosis of CFE can be challenging. Magnetic resonance imaging (MRI) of brain typically shows multiple lesions distributed predominantly in the subcortical region, which appear as hyperintense lesions on T2 and diffusion weighted images. Although the location offers a clue, the MRI findings are not specific for CFE. Watershed infarcts, hypoxic encephalopathy, disseminated infections, demyelinating disorders, diffuse axonal injury can also show similar changes on MRI of brain. The presence of fat in these hyperintense lesions, identified by MR spectroscopy as raised lipid peaks will help in accurate diagnosis of CFE. Normal brain tissue or conditions producing similar MRI changes will not show any lipid peak on MR spectroscopy. We present a case of CFE initially misdiagnosed as brain stem stroke based on clinical presentation and cranial computed tomography (CT) scan, and later, MR spectroscopy elucidated the accurate diagnosis.

Post-operative arterial thrombosis with non-vitamin K antagonist oral anticoagulants after total hip or knee arthroplasty

The incidence of post-operative arterial thrombosis (AT) (acute myocardial infarction [AMI] and ischaemic stroke) is increased in patients undergoing total hip replacement (THR) or total knee replacement (TKR). We compared the incidence of post-operative AT in non-vitamin K antagonist oral anticoagulants (NOACs)-treated and enoxaparin-treated patients, performing a systematic review of phase III randomised controlled trials (RCTs) of venous thromboembolism (VTE) prophylaxis in THR and TKR. Studies were identified by electronic search of MEDLINE and EMBASE database until July 2014. Differences between NOACs and enoxaparin groups in the efficacy and safety outcomes were expressed as odds ratios (ORs) with pertinent 95 % confidence intervals (95 % CI). Statistical heterogeneity was assessed with the I² statistic. Eleven phase III RCTs for a total of 31,319 patients were included. Patients underwent TKR in six studies and THR in five studies. The NOACs under study were dabigatran (four studies), apixaban (three studies) and rivaroxaban (four studies). AT occurred in 0.23 % of patients on NOACs and in 0.27 % of patients on enoxaparin: the OR at fixed-effect model was 0.86 (95 % CI 0.53-1.40; I² 11 %). No differences in AT incidence among the three NOACs were observed. The incidence of major and clinically relevant bleeding was similar in NOACs and enoxaparin groups (OR 1.03, 95 % CI 0.92-1.15; I² 38 %). In conclusion, in RCTs of pharmacological VTE prophylaxis in patients undergoing THR or TKR, there was no difference in the incidence of post-operative AT among patients treated with NOACs, compared to those treated with enoxaparin.

Effectiveness and safety of different duration of thromboprophylaxis in 16,865 hip replacement patients--a real-word, prospective observational study

INTRODUCTION

Clinical trials have provided evidence about efficacy and safety of extended thromboprophylaxis among total hip replacement (THR) patients. There is a lack of evidence on effectiveness and safety of extended treatment in unselected patients from routine clinical practice. We examined the effectiveness and safety of short (1-6 days) and standard (7-27 days) compared with extended (≥28 days) thromboprophylaxis using population-based design.

MATERIAL AND METHODS

Among all primary THR procedures performed in Denmark from 2010 through 2012 (n=16,865), we calculated adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for risk of symptomatic venous thromboembolism (VTE) and major bleeding, in addition to net clinical benefit, defined as the number of VTE avoided minus the number of excess bleeding events occurring among patients prescribed short-term and standard versus extended treatment.

RESULTS

The 90-day risks of VTE were 1.1% (short), 1.4% (standard), and 1.0% (extended), yielding aHRs of 0.83 (95% CI: 0.52-1.31) and 0.82 (95% CI: 0.50-1.33) for short and standard versus extended treatment. The risk of major bleeding was 1.1% (short), 1.0% (standard), and 0.7% (extended), resulting in aHRs of 1.64 (95% CI: 0.83-3.21) and 1.24 (95%CI: 0.61-2.51) for short and standard versus extended thromboprophylaxis. Direct comparison between benefits and harms using net clinical benefit analyses did not favor any of the three treatment durations. The same results were found for VTE or death.

CONCLUSIONS

In a real-word observational cohort of unselected THR patients, we observed no difference in the risks of symptomatic VTE, VTE/ death or bleeding with respect to thromboprophylaxis duration.

Recent surgery or invasive procedures and the risk of stroke

BACKGROUND AND PURPOSE

A recent surgery may be one of the trigger factors precipitating stroke and transient ischemic attack (TIA). While stroke in cardiac and carotid surgery has been well studied, less is known on stroke risk after surgery outside the heart and brain supplying arteries. We tested the hypothesis that preceding non-neurosurgical, non-cardiothoracic, and non-carotid surgery and other interventions temporarily increase the risk of stroke and transient ischemic attack (TIA) and investigated the risk related to different time periods between interventions and stroke/TIA.

METHODS

In the Ludwigshafen Stroke Study, a population-based stroke registry, we assessed surgery and other interventions within the year preceding stroke and TIA. The risk factor profiles of patients with and without prior intervention were compared and rate ratios (RR) were calculated for different time periods with 91-365 days before stroke and TIA serving as reference period.

RESULTS

In 2006 and 2007, 803 patients without and 116 patients with non-neurosurgical, non-cardiothoracic, and non-carotid intervention within the preceding year were identified. Elective (n = 21) and posttraumatic orthopedic (n = 14), eye (n = 14), and visceral surgery (n = 11) dominated. Interventions within 0-30 days (n = 34; RR 4.72; 95% confidence interval (CI) 2.70-8.26) but not within 31-60 or 61-90 days before stroke/TIA were observed more often than in the reference period. Interventions were more common within day 8-30 before stroke/TIA (RR 3.26; 95% CI 1.66-6.39), particularly common within the preceding week (RR 9.52; 95% CI 3.77-24.1) and most common in the preceding 2 days (RR 27.1; 95% CI 5.97-123) as compared to the reference period. Atrial fibrillation (AF) but not other risk factors was more common in patients with interventions within 30 days (n = 15; 44.1%) as compared to patients with more antecedent interventions (n = 19; 23.2%, p = 0.022) and those without surgery (n = 222; 27.6%, p = 0.031). Interventions within 30 days before stroke/TIA, were associated with total ischemic stroke (RR 6.11; 95% CI 3.32-11.2), first-ever in a lifetime ischemic stroke (RR 5.62; 95% CI 2.83-11.1) and recurrent ischemic stroke (RR 7.50; 95% CI 2.88-19.6).

CONCLUSION

Recent non-cardiothoracic, non-carotid, and non-neurosurgical interventions are associated with an increased risk of stroke lasting for about 1 month and being particularly high within the first days. AF may be among the mechanisms linking interventions and stroke besides induction of a procoagulant state and interruption of medication.

Efficacy of autologous bone marrow concentrate for knee osteoarthritis with and without adipose graft

Introduction. We investigated the use of autologous bone marrow concentrate (BMC) with and without an adipose graft, for treatment of knee osteoarthritis (OA). Methods. Treatment registry data for patients who underwent BMC procedures with and without an adipose graft were analyzed. Pre- and posttreatment outcomes of interest included the lower extremity functional scale (LEFS), the numerical pain scale (NPS), and a subjective percentage improvement rating. Multivariate analyses were performed to examine the effects of treatment type adjusting for potential confounding factors. The frequency and type of adverse events (AE) were also examined. Results. 840 procedures were performed, 616 without and 224 with adipose graft. The mean LEFS score increased by 7.9 and 9.8 in the two groups (out of 80), respectively, and the mean NPS score decreased from 4 to 2.6 and from 4.3 to 3 in the two groups, respectively. AE rates were 6% and 8.9% in the two groups, respectively. Although pre- and posttreatment improvements were statistically significant, the differences between the groups were not. Conclusion. BMC injections for knee OA showed encouraging outcomes and a low rate of AEs. Addition of an adipose graft to the BMC did not provide a detectible benefit over BMC alone.

The effect of body mass index on the risk of post-operative complications during the 6 months following total hip replacement or total knee replacement surgery

OBJECTIVE

To assess the effect of obesity on 6-month post-operative complications following total knee (TKR) or hip (THR) replacement.

DESIGN

Data for patients undergoing first THR or TKR between 1995 and 2011 was taken from the Clinical Practice Research Datalink. Logistic regression was used to assess whether body mass index (BMI) was associated with 6-month post-operative complications [deep vein thrombosis or pulmonary embolism (DVT/PE), myocardial infarction (MI), stroke, respiratory infection, anaemia, wound infection, urinary tract infection or death] after controlling for the effects of age, gender, smoking, drinking, socio-economic status (SES), co-morbidities and medications.

RESULTS

31,817 THR patients and 32,485 TKR patients were identified for inclusion. Increasing BMI was associated with a significantly higher risk of wound infections, from 1.6% to 3.5% in THR patients (adjusted P < 0.01), and from 3% to 4.1% (adjusted P < 0.05) in TKR patients. DVT/PE risk also increased with obesity from 2.2% to 3.3% (adjusted P < 0.01) in THR patients and from 2.0% to 3.3% (adjusted P < 0.01) in TKR patients. Obesity was not associated with increased risk of other complications.

CONCLUSION

Whilst an increased risk of wound infection and DVT/PE was observed amongst obese patients, absolute risks remain low and no such association was observed for MI, stroke and mortality. However this is a selected cohort (eligible for surgery according to judgement of NHS GPs and surgeons) and as such these results do not advocate surgery be given without consideration of BMI, but indicate that universal denial of surgery based on BMI is unwarranted.

The risk of venous thromboembolism, myocardial infarction, stroke, major bleeding and death in patients undergoing total hip and knee replacement: a 15-year retrospective cohort study of routine clinical practice

We examined the risk of thrombotic and major bleeding events in patients undergoing total hip and knee replacement (THR and TKR) treated with thromboprophylaxis, using nationwide population-based databases. We identified 83 756 primary procedures performed between 1997 and 2011. The outcomes were symptomatic venous thromboembolism (VTE), myocardial infarction (MI), stroke, death and major bleeding requiring hospitalisation within 90 days of surgery. A total of 1114 (1.3%) and 483 (0.6%) patients experienced VTE and bleeding, respectively. The annual risk of VTE varied between 0.9% and 1.6%, and of bleeding between 0.4% and 0.8%. The risk of VTE and bleeding was unchanged over a 15-year period. A total of 0.7% of patients died within 90 days, with a decrease from 1% in 1997 to 0.6% in 2011 (p < 0.001). A high level of comorbidity and general anaesthesia were strong risk factors for both VTE and bleeding, with no difference between THR and TKR patients. The risk of both MI and stroke was 0.5%, which remained unchanged during the study period. In this cohort study of patients undergoing THR and TKR patients in routine clinical practice, approximately 3% experienced VTE, MI, stroke or bleeding. These risks did not decline during the 15-year study period, but the risk of dying fell substantially.

Cerebrovascular disease is associated with outcomes after total knee arthroplasty: a US total joint registry study

We assessed the association of cerebrovascular disease preoperatively with patient-reported outcomes (PROs) of moderate-severe activity limitation and moderate-severe pain at 2- and 5-years after primary total knee arthroplasty (TKA) using multivariable-adjusted logistic regression; 7139 primary and 4234 revision TKAs were included. Compared to the patients without cerebrovascular disease, those with cerebrovascular disease had a higher odds ratio (OR) of moderate-severe limitation at 2 years and 5 years, 1.32 (95% confidence interval [CI]: 1.02, 1.72; P = .04) and 1.83 (95% CI: 1.32, 2.55; P < .001), respectively. No significant associations were noted with moderate-severe pain at 2 years or 5 years. In conclusion, we found that cerebrovascular disease is independently associated with pain and function outcomes after primary TKA. This should be taken into consideration when discussing expected outcomes of TKA with patients.

Prolonged outpatient vitamin K antagonist use and risk of venous thromboembolism in patients undergoing total hip or knee replacement

BACKGROUND

Long-term risk of venous thromboembolism (VTE) following total hip or knee replacement (THR/TKR) compared with controls has not been studied extensively, and the long-term influence of outpatient anticoagulant use on VTE risk remains unknown. The objectives were to evaluate long-term VTE risk following THR/TKR compared with matched controls, and to investigate effect modification by prolonged outpatient vitamin K antagonist use.

METHODS

A Danish retrospective nationwide cohort study was conducted. All patients undergoing primary THR/TKR (n = 95,227) between 1998 and 2007 were selected, each matched by age, sex and region with three controls (no THR/TKR). Patients were stratified by prolonged outpatient vitamin K antagonist use in the previous 3 months (in a time-dependent manner). All subjects were followed for VTE, and Cox models were used to calculate disease and medication history adjusted hazard ratios (HRs).

RESULTS

Within 6 weeks following surgery, a 13-fold increased risk of VTE was found for THR (adj. HR 12.9; 95% CI 11.2-14.7), and a 14-fold elevated risk for TKR (adj. HR 13.6; 95% CI 11.0-16.7), compared with matched controls. The risk remained substantially increased for at least 4 months following THR/TKR. Within this period, prolonged outpatient vitamin K antagonist use reduced the increase in VTE risk by 69% for THR and 54% for TKR.

CONCLUSION

The risk of VTE remains substantially elevated for at least 4 months following THR/TKR; this is well beyond the recommended duration of anticoagulant use. The increase in VTE risk is less pronounced in prolonged outpatient vitamin K antagonist users.