Serial D-dimers after anticoagulant cessation in unprovoked venous thromboembolism: Data from the REVERSE cohort study

INTRODUCTION

While several risk stratification tools have been developed to predict the risk of recurrence in patients with an unprovoked venous thromboembolism (VTE), only 1 in 4 patients are categorized as low-risk. Rather than a one-time measure, serial D-dimer assessment holds promise to enhance the prediction of VTE recurrence after oral anticoagulant (OAC) cessation.

METHODS

Using the REVERSE cohort, we compared VTE recurrence among patients with normal D-dimer levels (<490 ng/mL among males under age 70, <500 ng/mL in others) at OAC cessation and 1-month follow-up, to those with an elevated D-dimer level at either timepoint. We also evaluated VTE recurrence based on absolute increase in D-dimer levels between the two timepoints (e.g., ∆D-dimer) according to quartiles.

RESULTS

Among 214 patients with serial D-dimer levels measured at OAC cessation and 1-month follow-up, an elevated D-dimer level at either timepoint was associated with a numerically higher risk of recurrent VTE than patients with normal D-dimer levels at both timepoints (6.9 % vs. 4.2 % per year, hazard ratio 1.6; 95 % CI 0.9-2.7). Among women with <2 HERDOO2 criteria, a normal D-dimer level at both timepoints predicted a very low risk of recurrent VTE during follow-up (0.8 % per year, 95 % CI 0.1-2.8). Irrespective of baseline value, recurrent VTE risk was only 3 % per year (95 % CI 1.4-5.6) among patients in the lowest ∆D-dimer quartile.

CONCLUSION

Serial normal D-dimer levels have the potential to identify patients at a low risk of recurrent VTE. In addition, ∆D-dimer, irrespective of its elevation above cutoff threshold, may predict recurrent VTE.

In adults with VTE who received anticoagulants for ≥3 mo, VTE-PREDICT predicted recurrence and bleeding at up to 5 y

SOURCE CITATION

de Winter MA, Büller HR, Carrier M, et al; VTE-PREDICT study group. Recurrent venous thromboembolism and bleeding with extended anticoagulation: the VTE-PREDICT risk score. Eur Heart J. 2023;44:1231-1244. 36648242.

Incidence and Outcomes Associated with 6841 Isolated Distal Deep Vein Thromboses in Patients with 13 Common Cancers

INTRODUCTION

The epidemiology of isolated distal deep venous thrombosis (iDDVT) among cancer patients is not well described, particularly the incidence of recurrent venous thromboembolism (rVTE) and effect on mortality by cancer type.

METHODS

The cumulative incidence (CI) of iDDVT was determined for patients with 13 common cancers between 2005-2017 using the California Cancer Registry linked to the California Patient Discharge and Emergency Department Utilization datasets. The CI of rVTE was calculated and association of incident CAT location with rVTE was determined using Cox proportional hazards regression models. The association of incident cancer-associated venous thrombosis (CAT) location with overall and cancer-specific mortality was determined using Cox models, stratified by cancer site, and adjusted for individual characteristics.

RESULTS

Among 942,109 cancer patients, CAT occurred in 62,003 (6.6%): of these, 6,841 (11.0%) were iDDVT. Compared to more proximal sites of CAT, iDDVT was associated with similar risk for rVTE. IDDVT was associated with increased mortality across all cancer types when compared to patients without CAT (HR 1.56-4.60). The effect of iDDVT on mortality was similar to that of proximal DVT (pDVT) for most cancers except lung, colorectal, bladder, uterine, brain, and myeloma, where iDDVT was associated with a lesser association with mortality.

CONCLUSION

iDDVT represented 11% of CAT. The risk of rVTE after iDDVT was similar to other sites of CAT and rVTE occurred in more proximal locations after an incident iDDVT. IDDVT was associated with increased mortality and this effect was similar to that of PE or pDVT for most cancer types.

Long-term risk of recurrent venous thromboembolism after a first contraceptive-related event: Data from REVERSE cohort study

INTRODUCTION

The risk of recurrent venous thromboembolism (VTE) after combined oral contraceptive (COC) use is variably reported. We assessed the long-term risk of recurrent VTE in women on COC at the time of a first VTE, in comparison to women without COC use. Our secondary aim assessed the impact of COC use on the recurrent VTE risk in high-risk and low-risk hyperpigmentation, edema, or redness in either leg; D-dimer level ≥250 μg/L; obesity with body mass index ≥30; or older age, ≥65 years (HERDOO2) subgroups.

METHODS

The REVERSE cohort study derived the HERDOO2 clinical decision rule to predict recurrent VTE in patients who discontinued anticoagulation after 5-7 months for a first unprovoked VTE. Incidence rates of recurrent VTE among women with and without COC exposure were calculated as the number of recurrent VTE over the number of person-years of follow-up, and Cox proportional hazards model was used to compare risks between groups.

RESULTS

The risk of recurrent VTE among COC users was 1.1% (95% confidence interval [CI] 0.3-2.9) per patient-year as compared with 3.2% per patient-year (95% CI 2.4-4.3) among nonusers (hazard ratio 0.37; 95% CI 0.1-1.0). Women who were COC users and high risk by HERDOO2 score had a recurrence rate of 3.5% (95% CI 0.4-12.5) compared with 6.1% (95% CI 4.3-8.5) among women who were non-COC users and at high risk by HERDOO2 score (HR 0.6, 95% CI 0.1-2.5).

CONCLUSIONS

Women who were COC users at the time of an otherwise unprovoked VTE event had a lower VTE recurrence rate during long-term follow-up, compared with nonusers. The use of HERDOO2 rule may help identify higher risk women with COC use.

In cancer-related VTE, DOACs reduce recurrent VTE compared with LMWH; groups do not differ for major bleeding

Haykal T, Zayed Y, Deliwala S, et al. Direct oral anticoagulant versus low-molecular-weight heparin for treatment of venous thromboembolism in cancer patients: an updated meta-analysis of randomized controlled trials. Thromb Res. 2020;194:57-65. 32788122.

Bariatric surgery to aLleviate OCcurrence of Atrial Fibrillation Hospitalization-BLOC-AF

Background

Obesity is associated with a higher incidence of atrial fibrillation (AF). Weight reduction improves outcomes in patients known to have AF.

Objective

The purpose of this study was to compare the incidence of heart failure (HF) or first-time AF hospitalization in obese patients undergoing bariatric surgery (BAS) vs other abdominal surgeries.

Methods

A retrospective cohort study was conducted using linked hospital discharge records from 1994–2014. Obese patients without known AF or atrial flutter (AFL) who had undergone abdominal hernia or laparoscopic cholecystectomy surgery were identified for each case that underwent BAS (2:1). Clinical outcomes were HF, first-time hospitalization for AF, AFL, gastrointestinal bleeding (GIB), and ischemic or hemorrhagic stroke. Outcomes were analyzed using conditional proportional hazard modeling accounting for the competing risk of death, adjusting for demographics and comorbidities.

Results

There were 1581 BAS cases and 3162 controls (48% age <50 years; 60% white; 79% female; mean CHA₂DS₂VASc score 1.6 ± 1.2) with follow-up of 66 months. Compared to controls, BAS cases had a significantly lower risk of new-onset AF (hazard ratio [HR] 0.71; 95% confidence interval [CI] 0.54–0.93) or HF (HR 0.74; 95% CI 0.60–0.91) but a higher risk of GIB (HR 2.1; 95% CI 1.5–3.0), with no differences in AFL, ischemic stroke, or hemorrhagic stroke. Reduction in AF improved as follow-up increased beyond 60 months.

Conclusion

In patients undergoing BAS, the risk of either HF or AF was reduced by ∼29% but with greater risk of GIB. The findings support the hypothesis that weight loss reduces the long-term risk of HF or incident AF hospitalization.

Analysis of Nitrite- and/or Nitrate-Processed Meats for N-Nitrosodimethylamine

A total of 51 samples of various meat products was analyzed for N-nitrosodimethylamine with a method demonstrated to be sensitive to 10 ppb. The identity of the amine in one ham sample was confirmed by mass spectrometry at the 5 ppb level, the highest quantity detected in the various samples by GLC analysis. The presence of N-nitrosodimethylamine in the other samples could not be definitely established, since the apparent levels were too low for confirmatory analysis.

Nitrosopyrrolidine in Cooked Bacon

N-Nitrosopyrrolidine has been found in cooked bacon but not in the raw bacon. Levels isolated from 8 commercial brands ranged from 10 to 108 ppb μg/kg). The identity of this nitrosamine has been confirmed by mass spectrometry.

Extraction and Estimation of Polycyclic Aromatic Hydrocarbons in Smoked Foods. I. General Method

A method for the isolation and determination of polycyclic aromatic hydrocarbons in smoked foods has been developed. The compounds are extracted with ethanol, saponified with potassium hydroxide in a Soxhlet apparatus, concentrated, diluted with water, and extracted with a hydrocarbon solvent. The polycyclic hydrocarbons are isolated by partition, paper, and thin layer chromatography and measured by ultraviolet and spectrophotofiuorometric procedures. Average recoveries of benzo(a)- pyrene, dibenz(a,h) anthracene, benz(a)- anthracene, and benzo(g,h,i)perylene, added to 500 g samples of frankfurters, cheese, and fish at levels of 2 ppb, ranged from 70 to 88%. The carcinogen, benzo(a)- pyrene, was isolated from smoked fish and ham samples at levels varying from 0.8 to 3.2 ppb.

Extraction and Estimation of Polycyclic Aromatic Hydrocarbons in Total Diet Composites

A general method for polycyclic aromatic hydrocarbons and a specific procedure for benzo(a)pyrene in various total diet composites (dairy products; oils, fats, and shortenings; beverages; meat, fish, and poultry; and root vegetables) have been developed. Recoveries ranged from 75 to 100% at the 2 ppb level. Pyrene and fluoranthene were found to be present in all of the total diet samples analyzed. Trace quantities of benzo ( a ) pyrene, benzo(k)- fluoranthene, benzo ( b ) fluoranthene, and other hydrocarbons were isolated from various lots of the oils, fats, and shortenings composites.

Extraction and Estimation of Polycyclic Aromatic Hydrocarbons in Vegetable Oils

A method has been developed for isolatingand determining polycyclic aromatic hydrocarbons in refined vegetable oils. The oils are diluted with an aliphatic solvent and the polycyclic compounds are extracted with dimethyl sulfoxide. They are isolated by column and thin layer chromatographic techniques and measured by ultraviolet and spectrofluorometric procedures. Average recoveries of benzo(a)pyrene, dibenz(a,h)- anthracene, benz(a)anthracene, and benzo-(g,h,i)perylene, added to 200 g oil samples at the 2 ppb level, ranged from 71 to 100%. Benzo(a)pyrene and other polycyclic hydrocarbons were isolated in trace quantities from soybean, cottonseed, corn, olive, and peanut oils.

Extraction and Estimation of Polycyclic Aromatic Hydrocarbons in Smoked Foods. II. Benzo (a) pyrene

The carcinogen benzo(a)pyrene has been isolated from various smoked foods by modification of the general procedure for polycyclic aromatic hydrocarbons described in Part I. Recoveries of benzo(a)pyrene, added to 75, 100, and 150 g samples of frankfurters, fish, and cheese at levels of 1–2 ppb, ranged from 73 to 100%. Positive identification of the hydrocarbon recovered from feeds at levels as low as 0.02 ppb can be made from its fluorescence spectra.

CAABL-AF (California Study of Ablation for Atrial Fibrillation): Mortality and Stroke, 2005 to 2013

BACKGROUND

Ablation for atrial fibrillation (AF) is superior to medical therapy for rhythm control. We compared stroke and mortality among patients undergoing ablation for AF to matched controls in a large multiethnic population.

METHODS

Using discharge and surgical records from California nonfederal hospitals, we identified patients who had ablation and principal diagnosis of AF with at least 1 prior hospitalization for AF. We excluded cases with valve disease, open maze, other arrhythmias, or implantable devices. Matched controls were selected based on years of AF diagnosis, age, sex, and being alive the same number of days from the initial AF encounter to the ablation date. Clinical outcomes, including mortality, ischemic stroke, or hemorrhagic stroke, were assessed using a weighted proportional hazard model, adjusting for demographics, prior admissions with AF before the ablation, calendar year, and presence of chronic comorbidities.

RESULTS

There were 4169 ablation cases and 4169 weighted-matched controls; 39% percent of the ablation group was >65 years, 72% men, 84% white; mean follow-up was up to 3.6±0.9 years. In adjusted models, ablation was associated with significantly lower mortality (per patient-years) 0.9% versus 1.9%, hazard ratio=0.59 (P<0.0001; confidence interval: 0.45-0.77); ischemic stroke (>30 days post-ablation ≤5 years), 0.37% versus 0.59%, hazard ratio=0.68 (P=0.04; confidence interval: 0.47-0.97); hemorrhagic stroke 0.11% versus 0.35%, hazard ratio=0.36 (P=0.001; confidence interval: 0.20-0.64) compared with controls.

CONCLUSIONS

In this large population-based study of hospitalized patients with nonvalvular AF, ablation was associated with lower mortality, ischemic stroke, and hemorrhagic stroke compared with controls.

California Study of Ablation for Atrial Fibrillation:Re-hospitalization for Cardiac Events (CAABL-CE)

Background

Catheter ablation (ABL) for non-valvular (NV) atrial fibrillation (AF) improves rhythm control. Our aim was to compare re-hospitalization for heart failure (HF), acute coronary syndrome (ACS), or recurrent AF among patients with NVAF who underwent ABL versus controls.

Methods

From the Office of Statewide Planning and Development (OSHPD) database, we identified all patients who had at least one hospitalization for AF between 2005-2013. Patients who subsequently underwent ABL were compared to controls (up to fivematched controls by age, sex and duration of AF between diagnosis and time of ABL). Cases with valve disease, open maze, other arrhythmias, or implanted cardiac devices were excluded. Pre-specified clinical outcomes including readmission for HF, ACS, severe or simple AF (severe = with HF or ACS; simple= without HF or ACS)were assessed using a weighted proportional hazard model adjusting for number of hospital admissions with AF before the ABL, calendar year of ABL, and presence of chronic comorbidities.

Results

The study population constituted 8338 cases and controls, with mean 3.5+ 1 patient-year follow up. In the ABL cohort, there was lower risk of re-hospitalizations for HF, HR=0.55(95%CI: 0.43-0.69,); ACS,HR=0.5(95%CI: 0.35-0.72,); severe AF [HR=0.86 (CI:0.74-0.99), and higher for simple AF, HR=1.25 (CI:1.18-1.33).

Conclusions

In patients with NVAF,although ABL is associated with increased risk of re-hospitalization for simple AF, ABL was associated with a significant reduction in the risk of re-hospitalization for HF, ACS and severe AF. These findingsrequireconfirmation in a prospective clinical trial.

Postoperative Stiffness Requiring Manipulation Under Anesthesia Is Significantly Reduced After Simultaneous Versus Staged Bilateral Total Knee Arthroplasty

BACKGROUND

For patients with symptomatic bilateral knee arthritis, it is unknown whether the risk of developing stiffness requiring manipulation under anesthesia postoperatively is higher or lower for those undergoing simultaneous bilateral total knee arthroplasty (TKA) compared with those having staged bilateral TKA. Therefore, we undertook this study to evaluate the risk of requiring manipulation under anesthesia in staged versus simultaneous bilateral TKA as well as patients undergoing unilateral TKA.

METHODS

We utilized the California Patient Discharge Database, which is linked with the California Emergency Department, Ambulatory Surgery, and master death file databases. Using a literature-based estimate of the number of patients who failed to undergo the second stage of a staged bilateral TKA, replacement cases were randomly selected from patients who had unilateral TKA and were matched on 8 clinical characteristics of the patients who had staged bilateral TKA. Hierarchical multivariate logistic regression was performed to determine the risk-adjusted odds of manipulation in patients undergoing unilateral TKA, staged bilateral TKA, and simultaneous bilateral TKA using yearly hospital TKA volume as a random effect. Adjustment was made to allow fair comparison of the outcome at 90 and 180 days of follow-up after staged compared with simultaneous bilateral TKA.

RESULTS

During the time period from 2005 through 2013, the cumulative incidence of manipulation within 90 days was 2.14% for unilateral TKA (4,398 events per 205,744 patients), 2.11% for staged bilateral TKA (724 events per 34,352 patients), and 1.62% for simultaneous bilateral TKA (195 events per 12,013 patients). At 180 days of complete follow-up, the cumulative incidence of manipulation was 3.07% after unilateral TKA (6,313 events per 205,649 patients), 2.89% after staged bilateral TKAs (957 events per 33,169 patients), and 2.29% after simultaneous bilateral TKA (267 events per 11,653 patients). With multivariate analyses used to adjust for relevant risk factors, the 90-day odds ratio (OR) of undergoing manipulation after simultaneous bilateral TKA was significantly lower than that for unilateral TKA (OR = 0.70; 95% confidence interval [CI], 0.57 to 0.86) and staged bilateral TKA (OR = 0.71; 95% CI, 0.57 to 0.90). Similarly, at 180 days, the odds of undergoing manipulation were significantly lower after simultaneous bilateral TKA than after both unilateral TKA (OR = 0.71; 95% CI, 0.59 to 0.84) and staged bilateral TKA (OR = 0.76; 95% CI, 0.63 to 0.93). The frequency of manipulation was significantly associated with younger age, fewer comorbidities, black race, and the absence of obesity.

CONCLUSIONS

Although the ORs were small (close to 1), simultaneous bilateral TKA had a significantly decreased rate of stiffness requiring manipulation under anesthesia at 90 days and 180 days after knee replacement compared with that after staged bilateral TKA and unilateral TKA.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Racial and gender differences in the incidence of recurrent venous thromboembolism

Men have been reported to have a higher incidence of recurrent venous thromboembolism than women. However, it is not known if this gender effect holds among different racial/ethnic groups and for both venous thrombosis and pulmonary embolism. We conducteda retrospective analysis of 18-to 65-year-old Caucasian, African-American and Hispanic cases hospitalized in California with unprovoked venous thromboembolism. The principal outcome was recurrent venous thromboembolism 7–60 months after the index event. Among 11,514 cases that were followed for a mean of 3.0 years, men had a significantly higher rate (events/100 patient-years) of recurrent venous thromboembolism than women for both venous thrombosis [rate ratio (RR)=1.5, 95% confidence interval (CI):1.3–1.8] and pulmonary embolism [RR=1.3, 95%CI:1.0–1.6].Among men the recurrence rate did not vary significantly between the racial/ethnic groups (p>0.05). However, the recurrence rate among Hispanic women with venous thrombosis was significantly higher than in Caucasian women (p<0.001) and was comparable to the rate in men. Both Hispanic and African-American women with pulmonary embolism had a higher recurrence rate compared with Caucasian women (p<0.02) that was comparable to the rate in men. We conclude that women in California had a 40% lower risk of recurrent venous thromboembolism compared to men. Rates were comparable among men of different races, but there were significant inter-racial differences among women, which also varied with the type of initial event. The effect of gender on the risk of recurrent venous thromboembolism can not be generalized because it varies between racial/ethnic groups and with the type of index event.

Deficit Irrigation and Fertility Effects on NO3-N Exports from St. Augustinegrass

Proper management of turfgrass systems is critical for reducing the risk of nutrient loss and protecting urban surface waters. In the southern United States, irrigation can be the most significant management practice regulating the biogeochemical and hydrological cycles of turfgrass systems. A turfgrass runoff research facility was used to assess the effects of deficit irrigation and fertilizer applications on turfgrass canopy cover and nitrate-N (NO-N) exports in runoff from St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] turf over a 2-yr period. Treatments were arranged as a randomized complete block design having eight combinations of irrigation (100, 75, or 50% of estimated turfgrass water requirements) and fertility level (0, 88, and 176 kg N ha yr). Runoff from 31 rainfall events and one irrigation excess event were used to estimate annual and seasonal NO-N exports. The majority of annual NO-N exports occurred during the late winter and spring. Deficit irrigation reduced summer and early autumn runoff volumes. Lower summer and autumn runoff volumes (from deficit irrigation) coincided with reduced NO-N exports from runoff during Year 1. Deficit irrigation combined with fertilizer applications increased runoff [NO-N] in Year 2, suggesting that the previous year's export reduction contributed to higher N accumulation in the system and thus a higher N loss potential. These findings suggest that deficit irrigation can be a tool for reducing seasonal nutrient exports from St. Augustinegrass lawns so long as fertilizer inputs are moderate.

California study of Ablation (CAABL):early utilization after index hospitalization for non-valvular atrial fibrillation

Background

Catheter ablation (ABL) for non-valvular AF (NVAF) is recommended for symptomatic patients refractory to medical therapy and its success is related to the duration of the arrhythmia prior to intervention.Our aim was to assess the early utilization and the factors that prompted ABL in patients hospitalized for new onset NVAF.

Methods

Using de-identified administrative discharge records for hospitalizations and emergency department (ED) visits, we determined the patients who had a first-time (since 1991) health record diagnosis of AF between2005 - 2011. We linked ambulatory surgery encounters for ABL based on ICD 9 code occurring within two years of initial hospitalization. After excluding other cardiac arrhythmias, atrio-ventricular nodal ablation or pacemaker/defibrillator placement and cardiac valve disease, bivariate comparisons were made with those who did not undergo ABL.

Results

During the study period,3,440 of 424,592 patients (0.81%) hospitalized for new onset NVAF underwent ABL. Parameters significantly (p<0.001) associated with ABL compared tonon-ABL patientsincluded: principal diagnosis of AF (55% vs 25%), age 35-64 yrs (46.1% vs. 22.4%), male (58.9% vs. 48.2%), private insurance (46.6% vs. 21.1%), Caucasian (81.0% vs.71.6%), lower frequency of ED visit < 6 months before index AF hospitalization (10.7% vs. 15.9%), lower severityofillness at time of AF diagnosis (16.5% vs. 35.6%) anda lower prevalence ofmajor comorbidities (p< 0.001).

Conclusions

Ablation has low utilization for treatment of new onset NVAF within two years of diagnosis. Earlier utilization of ABL may reduce health care burden related to NVAF and requires further evaluation.

Increased incidence of VTE in sickle cell disease patients: risk factors, recurrence and impact on mortality

Previous reports show increased incidence of venous thromboembolism [VTE, deep-vein thrombosis (DVT) and pulmonary embolus (PE)] in sickle cell disease (SCD) patients but did not account for frequency of hospitalization. We determined the incidence of VTE in a SCD cohort versus matched controls. For SCD patients, risk factors for incident VTE, recurrence and the impact on mortality were also determined. Among 6237 patients with SCD, 696 patients (11·2%) developed incident-VTE: 358 (51·6%) had PE (±DVT); 179 (25·7%) had lower-extremity DVT only and 158 (22·7%) had upper-extremity DVT. By 40 years of age, the cumulative incidence of VTE was 17·1% for severe SCD patients (hospitalized ≥3 times a year) versus 8·0% for the matched asthma controls. Amongst SCD patients, women (Hazard ratio [HR] = 1·22; 95% confidence interval [CI]: 1·05-1·43) and those with severe disease (HR = 2·86; 95% CI: 2·42-3·37) had an increased risk of VTE. Five-year recurrence was 36·8% in patients with severe SCD. VTE was associated with increased risk of death (HR = 2·88, 95% CI: 2·35-3·52). In this population-based study, the incidence of VTE was higher in SCD patients than matched controls and was associated with increased mortality. The high incidence of recurrent VTE in patients with severe SCD suggests that extended anticoagulation may be indicated.

Reducing the incidence of hospital-associated venous thromboembolism within a network of academic hospitals: Findings from five University of California medical centers

BACKGROUND

Almost 700 patients suffered from hospital-associated venous thromboembolism (HA-VTE) across 5 University of California hospitals in calendar year 2011.

OBJECTIVE

Optimize venous thromboembolism (VTE) prophylaxis (VTEP) in adult medical/surgical inpatients and reduce HA-VTE by at least 20% within 3 years.

DESIGN

Prospective, unblinded, open-intervention study with historical controls.

SETTING

Five independent but cooperating academic hospitals.

PATIENTS

All adult medical and surgical inpatients with stays ≥3 days. The baseline year was 2011, 2012 to 2014 were intervention years, and year 2014 was the mature comparison period. VTEP adequacy was assessed with structured chart review of 45 patients per month at each site via random selection beginning partway through the study. HA-VTE was identified by discharge coding, capturing patients readmitted within 30 days of prior VTE-free admit and VTE occurring during index admission. Cases were stratified medical versus surgical and cancer or noncancer.

INTERVENTIONS

Interventions included structured order sets with "3-bucket" risk-assessment, measure-vention, techniques to improve reliable administration of VTEP, and education.

RESULTS

Adequate prophylaxis reached 89% by early 2014. The rate of HA-VTE fell from 0.90% in 2011 to 0.69% in 2014 (24% relative risk [RR] reduction; RR: 0.76, 95% confidence interval: 0.68-0.852), equivalent to averting 81 pulmonary emboli and 89 deep venous thrombi. VTE rates were highest in cancer and surgical patients.

CONCLUSIONS

Hospital systems can reduce HA-VTE by implementing a bundle of active interventions including structured VTEP orders with embedded risk assessment and measure-vention. Journal of Hospital Medicine 2016;11:S22-S28. © 2016 Society of Hospital Medicine.

Therapeutic Anticoagulation for Isolated Calf Deep Vein Thrombosis

IMPORTANCE

Deep vein thrombosis (DVT) isolated to the calf veins (distal to the popliteal vein) is frequently detected with duplex ultrasonography and may result in proximal thrombosis or pulmonary embolism (PE).

OBJECTIVE

To evaluate whether therapeutic anticoagulation is associated with a decreased risk for proximal DVT or PE after diagnosis of an isolated calf DVT.

DESIGN, SETTING, AND PARTICIPANTS

All adult patients with ultrasonographic detection of an isolated calf DVT from January 1, 2010, to December 31, 2013, at the Vascular Laboratory of the University of California, Davis, Medical Center were included. Patients already receiving therapeutic anticoagulation and those with a chronic calf DVT, a contraindication to anticoagulation, prior venous thromboembolism within 180 days, or diagnosis of a PE suspected at the time of calf DVT diagnosis were excluded. Data were analyzed from August 18, 2015, to February 14, 2016.

EXPOSURES

Intention to administer therapeutic anticoagulation.

MAIN OUTCOMES AND MEASURES

Proximal DVT or PE within 180 days of the diagnosis of the isolated calf DVT.

RESULTS

From 14 056 lower-extremity venous duplex studies, we identified 697 patients with an isolated calf DVT and excluded 313 of these. The remaining 384 patients were available for analysis (222 men [57.8%]; 162 women [42.2%]; mean [SD] age, 60 [16] years). The calf DVT involved an axial vein (anterior tibial, posterior tibial, or peroneal) in 243 patients (63.2%) and a muscular branch (soleus or gastrocnemius) in 215 (56.0%). Physicians attempted to administer therapeutic anticoagulation in 243 patients (63.3%), leaving 141 control participants. Proximal DVT occurred in 7 controls (5.0%) and 4 anticoagulation recipients (1.6%); PE, in 6 controls (4.3%) and 4 anticoagulation recipients (1.6%). Therapeutic anticoagulation was associated with a decreased risk for proximal DVT or PE at 180 days (odds ratio [OR], 0.34; 95% CI, 0.14-0.83) but an increased risk for bleeding (OR, 4.35; 95% CI, 1.27-14.9), findings that persisted after adjustment for confounding factors (ORs, 0.33 [95% CI, 0.12-0.87] and 4.87 [95% CI, 1.37-17.3], respectively) and sensitivity analyses.

CONCLUSIONS AND RELEVANCE

Rates of proximal DVT or PE are low after isolated calf DVT. Therapeutic anticoagulation is associated with a reduction of these outcomes but an increase in bleeding.

Outcomes After Vena Cava Filter Use in Noncancer Patients With Acute Venous Thromboembolism: A Population-Based Study

BACKGROUND

Evidence that vena cava filters (VCFs) are beneficial is limited.

METHODS AND RESULTS

We retrospectively analyzed all noncancer patients admitted to nonfederal California hospitals for acute venous thromboembolism from 2005 to 2010. Analysis was stratified by the presence/absence of a contraindication to anticoagulation (active bleeding, major surgery). Outcomes were death within 30 or 90 days of admission and the 1-year incidence of recurrent venous thromboembolism manifested as pulmonary embolism or deep vein thrombosis. Propensity score methods were used to account for observed systematic differences in baseline characteristics between patients treated and those not treated with a VCF. Among 80 697 patients with no contraindication to anticoagulation, VCF use (n=7762, 9.6%) did not significantly reduce the 30-day risk of death (hazard ratio [HR], 1.12; 95% confidence interval [CI], 0.98-1.28). Among 3017 patients with active bleeding, VCF use (n=1095, 36.3%) reduced the 30-day risk of death by 32% (HR, 0.68; 95% CI, 0.52-0.88) and the 90-day risk by 27% (HR, 0.73; 95% CI, 0.59-0.90). VCF use (n=489, 33.8%) did not reduce mortality among 1445 patients who underwent major surgery (HR, 1.1; 95% CI, 0.71-1.77). In all subgroups, filter use did not reduce the risk of subsequent pulmonary embolism. However, the risk of subsequent deep vein thrombosis increased by 50% among VCF patients with no contraindication (HR, 1.53; 95% CI, 1.34-1.74) and by 135% among VCF patients with active bleeding (HR, 2.35; 95% CI, 1.56-3.52).

CONCLUSIONS

VCF use significantly reduced the short-term risk of death only among patients with acute venous thromboembolism who had a contraindication to anticoagulation because of active bleeding. These results support the findings of a randomized clinical trial and current guidelines that recommend VCF use only in patients who cannot receive anticoagulation treatment.

The epidemiology of venous thromboembolism

Venous thromboembolism (VTE) is categorized by the U.S. Surgeon General as a major public health problem. VTE is relatively common and associated with reduced survival and substantial health-care costs, and recurs frequently. VTE is a complex (multifactorial) disease, involving interactions between acquired or inherited predispositions to thrombosis and VTE risk factors, including increasing patient age and obesity, hospitalization for surgery or acute illness, nursing-home confinement, active cancer, trauma or fracture, immobility or leg paresis, superficial vein thrombosis, and, in women, pregnancy and puerperium, oral contraception, and hormone therapy. Although independent VTE risk factors and predictors of VTE recurrence have been identified, and effective primary and secondary prophylaxis is available, the occurrence of VTE seems to be relatively constant, or even increasing.

Cost-effectiveness of edoxaban for the treatment of venous thromboembolism based on the Hokusai-VTE study

OBJECTIVE

Venous thromboembolism (VTE) is associated with almost 300,000 deaths per year in the United States. Novel oral anticoagulants (NOACs) offer an alternative to warfarin-based therapy without monitoring requirements and with fewer drug and food interactions. Edoxaban, a direct Xa inhibitor, is approved by the Food and Drug Administration (FDA), based upon results of the Hokusai-VTE Phase 3 trial. The trial demonstrated that edoxaban administered once daily after initial treatment with heparin was non-inferior in reducing the risk of VTE recurrence and caused significantly less major and clinically relevant non-major (CRNM) bleeding compared to warfarin. The objective of this study was to evaluate the cost-effectiveness of edoxaban versus warfarin for the treatment of adults with VTE.

METHODS

A cost-effectiveness model was developed using patient-level data from the Hokusai-VTE trial, clinical event costs from real-world databases, and drug acquisition costs for warfarin of $0.36 and edoxaban of $9.24 per tablet.

RESULTS

From a U.S. health-care delivery system perspective, the incremental cost-effectiveness ratio (ICER) was $22,057 per quality adjusted life year (QALY) gained. Probabilistic sensitivity analysis showed that edoxaban had an ICER <$50,000 per QALY gained relative to warfarin in 67% of model simulations. The result was robust to variation in key model parameters including the cost and disutility of warfarin monitoring.

CONCLUSION

Despite its higher drug acquisition cost, edoxaban is a cost-effective alternative to warfarin for the treatment of VTE.

Do Women Have Worse Amputation-Free Survival Than Men Following Endovascular Procedures for Peripheral Arterial Disease? An Evaluation of the California State-Wide Database

Objectives:

Female gender has been shown to negatively affect the outcomes of surgical bypass for peripheral arterial disease (PAD). We examined gender-related disparities in outcomes of endovascular PAD procedures in a large population-based study.

Methods:

We used discharge data from California hospitals to identify patients who had PAD interventions during 2005 to 2009. Logistic regression was used for 12-month reintervention, and Cox proportional hazard regression was used for amputation-free survival comparisons.

Results:

A total of 25 635 patients had endovascular procedures (11 389 [44.4%] women). Women were more likely than men (34.5% vs 30.1%, P < .0001) to have critical limb ischemia (CLI). Twelve-month reintervention rate in women was similar to men. Amputation-free survival was better among women than men (hazard ratio 0.84, 95% confidence interval [CI] 0.76-0.93, P = .0006).

Conclusion:

Despite presenting more frequently with CLI, women had better amputation-free survival than men following endovascular procedures. Future research should determine whether findings favor one type of PAD treatment modality over another for women.

Nitrogen Runoff Losses during Warm-Season Turfgrass Sod Establishment

Concern exists over the potential loss of nitrogen (N) and phosphorus (P) in runoff from newly established and fertilized lawns. Nutrient losses can be higher from turf when shoot density and surface cover are low and root systems are not fully developed. This study was conducted to evaluate fertilizer source and timing effects on nutrient losses from newly sodded lawns of St. Augustinegrass [ (Walt.) Kuntze]. For each study, 12 33.6-m plots were established on an undisturbed Alfisol having a 3.7% slope. Each plot was equipped with a runoff collection system, instrumentation for runoff flow rate measurement, and automated samplers. A 28-d establishment study was initiated on 8 Aug. 2012 and repeated on 9 Sept. 2012. Treatments included unfertilized plots, fertilized plots receiving 4.88 g N m as urea 6 d after planting, fertilized plots receiving 4.88 g N m as sulfur-coated urea 6 d after planting, and fertilized plots receiving 4.88 g N m as urea 19 d after planting. Runoff events were created by irrigating with 17 mm of water over 27 min. Runoff water samples were collected after every 37.8 L and analyzed for NO-N, NH-N, dissolved organic N (DON), and PO-P. Increases of approximately 2 to 4 mg L NO-N and 8 to 12 mg L PO-P occurred in runoff 1 d after fertilization, which returned to background levels within 7 d. Total fertilizer N lost to runoff was 0.6 to 4.2% of that applied. Delaying fertilizer application until 19 d after planting provided no reduction in nutrient loss compared with a similar application 6 d after planting. Approximately 33% of the N lost in runoff was as DON. This large amount of DON suggests significant N loss from decomposing organic matter may occur during sod establishment.

Lymphoma and venous thromboembolism: influence on mortality

BACKGROUND

The population-based incidence of acute venous thromboembolism (VTE) in adult patients diagnosed with non-Hodgkin's lymphoma has not been established, and the effect of VTE on survival is not clear.

AIM

To determine the incidence of acute VTE in California residents diagnosed with lymphoma, and to determine the effect of acute VTE on survival.

METHODS

We used the California Cancer Registry coupled with the California Patient Discharge database to identify incident cases with lymphoma, 1991-1997, and the incidence of first-time VTE in these patients. Multivariable models were constructed to evaluate risk of developing acute VTE within 2 years, and a proportional hazard model was used to predict death within 2 years, using acute VTE as a time-dependent covariate.

RESULTS

There were 16,755 patients diagnosed with non-Hodgkin's lymphoma; 29% had low-grade, 66% intermediate/aggressive grade and 5.6% had high-grade lymphoma. Acute VTE developed in 3.6% of the patients by year 1 and 4.0% by the end of year 2. Significant predictors of acute VTE included advanced stage lymphoma, number of chronic comorbidities and advancing age. Significant predictors of death within 2 years included diagnosis of acute VTE, advanced stage disease, increasing number of co-morbidities, age over 75 years and intermediate or high grade histopathology. The effect of acute VTE on death increased as the time between lymphoma diagnosis and VTE diagnosis increased (HR=1.7 95%CI:1.5-1.9 for VTEs <6 months; HR=6.5 95%CI:4.7-8.9 VTEs 12-24 months).

CONCLUSIONS

Acute VTE developed frequently in patients with lymphoma, and VTE was a strong predictor of decreased survival.

Design and construction of an urban runoff research facility

As the urban population increases, so does the area of irrigated urban landscape. Summer water use in urban areas can be 2-3x winter base line water use due to increased demand for landscape irrigation. Improper irrigation practices and large rainfall events can result in runoff from urban landscapes which has potential to carry nutrients and sediments into local streams and lakes where they may contribute to eutrophication. A 1,000 m(2) facility was constructed which consists of 24 individual 33.6 m(2) field plots, each equipped for measuring total runoff volumes with time and collection of runoff subsamples at selected intervals for quantification of chemical constituents in the runoff water from simulated urban landscapes. Runoff volumes from the first and second trials had coefficient of variability (CV) values of 38.2 and 28.7%, respectively. CV values for runoff pH, EC, and Na concentration for both trials were all under 10%. Concentrations of DOC, TDN, DON, PO₄₋P, K(+), Mg(2+), and Ca(2+) had CV values less than 50% in both trials. Overall, the results of testing performed after sod installation at the facility indicated good uniformity between plots for runoff volumes and chemical constituents. The large plot size is sufficient to include much of the natural variability and therefore provides better simulation of urban landscape ecosystems.

Younger age is associated with a higher risk of early periprosthetic joint infection and aseptic mechanical failure after total knee arthroplasty

BACKGROUND

Although early aseptic mechanical failure after total knee arthroplasty has been reported in younger patients, it is unknown whether early revision due to periprosthetic joint infection is more or less frequent in this patient subgroup. The purpose of this study was to determine whether the incidence of early periprosthetic joint infection requiring revision knee surgery is significantly different in patients younger than fifty years of age compared with older patients following primary unilateral total knee arthroplasty.

METHODS

A large population-based study was conducted with use of the California Patient Discharge Database, which allows serial linkage of all discharge data from nonfederal hospitals in the state over time. Patients undergoing primary unilateral total knee arthroplasty during 2005 to 2009 were identified. Principal outcomes were partial or complete revision arthroplasty due to periprosthetic joint infection or due to aseptic mechanical failure within one year. Multivariate analysis included risk adjustment for important demographic and clinical variables. The effect of hospital total knee arthroplasty volume on the outcomes of infection and mechanical failure was analyzed with use of hierarchical modeling.

RESULTS

At one year, 983 (0.82%) of 120,538 primary total knee arthroplasties had undergone revision due to periprosthetic joint infection and 1385 (1.15%) had undergone revision due to aseptic mechanical failure. The cumulative incidence in patients younger than fifty years of age was 1.36% for revision due to periprosthetic joint infection and 3.49% for revision due to aseptic mechanical failure. In risk-adjusted models, the risk of periprosthetic joint infection was 1.8 times higher in patients younger than fifty years of age (odds ratio = 1.81, 95% confidence interval = 1.33 to 2.47) compared with patients sixty-five years of age or older, and the risk of aseptic mechanical failure was 4.7 times higher (odds ratio = 4.66, 95% confidence interval = 3.77 to 5.76). The rate of revision due to infection at hospitals in which a mean of more than 200 total knee arthroplasties were performed per year was lower than the expected (mean) value (p = 0.04).

CONCLUSIONS

Patients younger than fifty years of age had a significantly higher risk of undergoing revision due to periprosthetic joint infection or to aseptic mechanical failure at one year after primary total knee arthroplasty.

Incidence of hospital-acquired venous thromboembolic codes in medical patients hospitalized in academic medical centers

BACKGROUND

Hospital-acquired venous thromboembolism (HA-VTE, VTE occurring during a hospitalization) codes in hospital billing data are often used as a surrogate for hospital-associated VTE events occurring during or up to 30 days after a hospitalization, which are more difficult to measure.

OBJECTIVE

Establish the incidence and composition of HA-VTE/superficial venous thrombosis (SVT) coded in a large cohort of medical patients.

DESIGN

Retrospective analysis of discharges.

SETTING

Eighty-three academic medical centers in UHC (formerly University HealthSystem Consortium).

PATIENTS

Patients with medical diagnoses hospitalized >2 days between October 1, 2009, and March 31, 2011.

MEASUREMENTS

Incidence and anatomic location of HA-VTE codes, defined as International Classification of Diseases, Ninth Revision, Clinical Modification codes for VTE coupled to a present-on-admission indicator flag set to "No."

RESULTS

Among 2,525,068 medical hospitalizations, 12,847 (0.51%) cases had ≥1 thrombotic code; 2449 (19.1%) with pulmonary embolism (PE), and 3848 (30%) with lower-extremity deep venous thrombosis (LE-DVT) without PE. Upper-extremity DVT (2893; 22.5%) and SVT (3248; 25.3%) comprised the bulk of remaining cases. Among cases with HA-PE/LE-DVT, 34.3% had cancer, 47.8% received care in an intensive care unit, 78% had severe or extreme severity of illness, and 16.5% died in the hospital. Overall, 54.9% of the patients who developed a HA-PE/LE-DVT had been started on VTE pharmacoprophylaxis on hospital day 1 or 2.

CONCLUSION

At academic centers, HA-VTE/SVT is coded in 0.51% of medical inpatients, and HA-PE/LE-DVT is coded in half of those. Most patients with HA-PE/LE-DVT are severely ill and develop VTE despite receiving prophylaxis.

High variation between hospitals in vena cava filter use for venous thromboembolism

BACKGROUND

The extent to which vena cava filter (VCF) use varies between hospitals in the management of acute venous thromboembolism (VTE) is not clear.

METHODS

We conducted a retrospective observational study that compared the frequency of VCF use among California hospitals from January 1, 2006, through December 31, 2010. Using administrative hospital discharge data, we followed explicit criteria to identify nontrauma patients with acute VTE, and determined the frequency of VCF placement in each of the hospitals that admitted more than 55 VTE patients. Multivariable hierarchical regression models to predict VCF use included important clinical and demographic variables as fixed effects and hospital as a random effect.

RESULTS

Among the 263 hospitals included, 130 643 acute VTE hospitalizations occurred with the placement of 19 537 VCFs (14.95%). Variation in the percentage of acute VTE hospitalizations that included VCF placement was very high, from 0% to 38.96% (interquartile range, 6.23%-18.14%), with 18.49% of the observed variation due to differences among the hospitals that provided care. Significant clinical predictors of VCF use included acute bleeding at the time of admission (odds ratio, 3.4 [95% CI, 3.2-3.6]), a major operation after admission for VTE (3.4 [3.3-3.5]), presence of metastatic cancer (1.7 [1.6-1.8]), and extreme severity of illness (2.5 [2.3-2.7] vs mild). Insertion of VCFs occurred more frequently than expected in 109 hospitals and less frequently in 59. Hospital characteristics associated with VCF use included a small number of beds (odds ratio, 0.2 [95% CI, 0.2-0.4], <100 vs >400 beds), a rural location (0.4 [0.2-0.5]), and other private vs Kaiser hospitals (1.5 [1.1-2.0]). Use of VCFs varied widely even in geographically proximate areas.

CONCLUSIONS

The frequency of VCF use in patients with acute VTE varied widely and depended on which hospital provided the care, even after adjusting for clinical and socioeconomic factors. Further research is needed to determine whether this variation is associated with local cultural differences between hospitals or with differences in the availability of interventional radiologists or specialists, or whether it reflects the absence of high-quality evidence that VCFs are effective.

Biomolecular markers of cancer-associated thromboembolism

Venous thromboembolism (VTE; deep venous thrombosis and pulmonary embolism) is associated with a poor prognosis in most malignancies and is a major cause of death among cancer patients. Universal anticoagulation for primary thromboprophylaxis in the outpatient setting is precluded by potential bleeding complications, especially without sufficient evidence that all patients would benefit from such prophylaxis. Therefore, appropriately targeting cancer patients for thromboprophylaxis is key to reducing morbidity and perhaps mortality. Predictive biomarkers could aid in identifying patients at high risk for VTE. Possible biomarkers for VTE include C-reactive protein, platelet and leukocyte counts, D-dimer and prothrombin fragment 1+2, procoagulant factor VIII, tissue factor, and soluble P-selectin. Evidence is emerging to support the use of risk assessment models in selecting appropriate candidates for primary thromboprophylaxis in the cancer setting. Further studies are needed to optimize these models and determine utility in reducing morbidity and mortality from cancer-associated thromboembolism.

Predictors of post-thrombotic syndrome in a population with a first deep vein thrombosis and no primary venous insufficiency

BACKGROUND

Post-thrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis (DVT). Its diagnosis is based on clinical characteristics. However, symptoms and signs of PTS are non-specific, and could result from concomitant primary venous insufficiency (PVI) rather than DVT. This could bias evaluation of PTS.

METHODS

Using data from the REVERSE multicenter study, we assessed risk factors for PTS in patients with a first unprovoked unilateral proximal DVT 5-7 months earlier who were free of clinically significant PVI (defined as absence of moderate or severe venous ectasia in the contralateral leg).

RESULTS

Among the 328 patients considered, the prevalence of PTS was 27.1%. Obesity (odds ratio [OR] 2.6 [95% confidence interval (CI) 1.5-4.7]), mild contralateral venous ectasia (OR 2.2 [95% CI 1.1-4.3]), poor International Normalized Ratio (INR) control (OR per additional 1% of time with INR < 2 during anticoagulant treatment of 1.018 [95% CI 1.003-1.034]) and the presence of residual venous obstruction on ultrasound (OR 2.1 [95% CI 1.1-3.7]) significantly increased the risk for PTS in multivariable analyses. When we restricted our analysis to patients without any signs, even mild, of contralateral venous insufficiency (n = 244), the prevalence of PTS decreased slightly to 24.6%. Only obesity remained an independent predictor of PTS (OR 2.6 [95% CI 1.3-5.0]). Poor INR control and residual venous obstruction also increased the risk, but the results were no longer statistically significant (OR 1.017 [95% CI 0.999-1.035] and OR 1.7 [95% CI 0.9-3.3], respectively).

CONCLUSIONS

After a first unprovoked proximal DVT, obese patients and patients with even mild PVI constitute a group at increased risk of developing PTS for whom particular attention should be paid with respect to PTS prevention. Careful monitoring of anticoagulant treatment may prevent PTS.

Anticoagulation education: do patients understand potential medication-related emergencies?

BACKGROUND

The Joint Commission Venous Thromboembolism (VTE) National Hospital Inpatient Quality Measure VTE-5 outlines four criteria for discharge patient education when starting anticoagulation (usually, warfarin) therapy. The criteria do not specify content regarding patient recognition of potentially dangerous warfarin-related scenarios. A study was conducted to investigate how well patients assess the risks and consequences of potential warfarin-related safety threats.

METHODS

From an adult population on long-term warfarin, 480 patients were randomly selected for a telephone-based survey. Warfarin-knowledge questions were drawn from a previous survey; warfarin-associated risk scenarios were developed via focus interviews. Expert anticoagulation pharmacists categorized each scenario as urgent, moderately urgent, or not urgent, as did survey participants.

RESULTS

For the 184 patients (38% completion rate), the mean knowledge score was 69% (standard deviation [SD], 0.20). Overall classification accuracy of situational urgency was 59% (95% confidence interval [CI], 57.3%-60.3%). Respondents overestimated non-urgent-severity situations 23% of the time (95% CI, 20.8%-24.7%), while underestimating urgent-severity situations 21% of the time (95% CI, 19.0%-23.9%). A significant percentage of patients failed to recognize the urgency of stroke symptoms (for example, loss of vision), the risk of bleeding after incidental head trauma, or medication mismanagement.

CONCLUSIONS

Despite fair factual warfarin knowledge, participants did not appear to recognize well the clinical severity of warfarin-associated scenarios. Warfarin education programs should incorporate patient-centered strategies to teach recognition of high-risk situations that compromise patient safety.

Mechanical and suboptimal pharmacologic prophylaxis and delayed mobilization but not morbid obesity are associated with venous thromboembolism after total knee arthroplasty: a case-control study

BACKGROUND

The FDA-approved dose of low-molecular-weight heparin (LMWH) may not provide adequate thromboprophylaxis in morbidly obese patients after total knee arthroplasty (TKA). Suboptimal dosing, delayed initiation, and overreliance on mechanical methods may also limit the effectiveness of thromboprophylaxis.

OBJECTIVE

We explored the associations between the type of thromboprophylaxis, obesity, time of mobilization, and undergoing bilateral TKA on development of symptomatic venous thromboembolism (VTE) after TKA.

DESIGN/SETTING/PATIENTS

This was a case-control study of patients undergoing TKA in 15 teaching hospitals between October 2008 and March 2010. Cases were screened using the Agency for Healthcare Research and Quality's Patient Safety Indicator 12 and had objectively documented acute VTE within 9 days of surgery; controls were randomly selected from the same hospital. Multivariable logistic regression was used to analyze risk factors for postoperative VTE, adjusted for age and gender.

RESULTS

Among 130 cases with and 463 controls without acute VTE, body mass index (BMI) ranged from 17 to 61 (median = 34). Thromboprophylaxis was LMWH in 284 (48%), warfarin in 189 (32%), both in 55 (10%), and mechanical prophylaxis alone in 120 (20%). Overall, 77% ambulated on day 1 or 2 after surgery. Factors significantly associated with VTE were bilateral simultaneous TKA (odds ratio [OR] = 4.2; 95% confidence interval [CI]: 1.9-9.1), receipt of FDA-approved pharmacological prophylaxis (OR = 0.5; 95% CI: 0.3-0.8), and ambulation by postoperative day 2 (OR = 0.3; 95% CI: 0.1-0.9). Obesity was neither a significant confounder nor a modifier of these effects.

CONCLUSIONS

Severe obesity was not a significant independent predictor for VTE and did not modify the beneficial effect of FDA-approved pharmacological thromboprophylaxis. Bilateral TKA and failure to ambulate by the second day after surgery were significant risk factors.