Incidence and Risk Factors Associated with Thromboembolic Events among Patients with COVID-19 Inpatients: A Retrospective Study

Aims and objectives

Despite thromboprophylaxis, some severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients develop thrombotic complications with poor prognosis. Our goal is to comprehensively assess the incidence, risk factors, and clinical outcomes associated with thromboembolic events (TE) among adult patients presenting with coronavirus disease-2019 (COVID-19).

Materials and methods

The study was conducted as an observational and retrospective study across COVID-19 patients (n = 207) in a tertiary care hospital in the Middle East and North Africa (MENA) region. Electronic health records were collected from the COVID-19 Database from April 2020 to December 2020 which included clinical history and TE.

Results

Fifty-six (27.05%) out of 207 patients (age: 54.42 ± 15.01 years) developed TE despite the anticoagulant therapy. The incidence of venous thromboembolism (VTE) was significantly higher for patients aged >50 years compared to <50 years (73.21% vs 26.79%, p < 0.05). There were no differences in the incidence of VTE between genders (p = 0.561). 165 patients (79.71%) received anticoagulant therapy, yet 48 (29%) developed TE. The most commonly used anticoagulant was low-molecular-weight heparin (LMWH, 47.34%). In spite of efficient treatment and medical management, the majority of patients with TE (45 out of 56 patients, 80.35%) experienced mortality. The comorbidities that significantly increase the risk of TE include hypertension (HTN) and ischemic heart disease (IHD). The laboratory parameters that were associated with an increased risk of VTE include ferritin, lactate dehydrogenase (LDH), and creatinine.

Conclusion

The COVID-19 patients develop thrombotic complications. Future studies should clarify the underlying mechanisms of TE and optimize the antithrombotic regimens in COVID-19 patients.

How to cite this article

Tashkandi WA. Incidence and Risk Factors Associated with Thromboembolic Events among Patients with COVID-19 Inpatients: A Retrospective Study. Indian J Crit Care Med 2023;27(11):830-836.

Renin-angiotensin inhibitors reduce thrombotic complications in Essential Thrombocythemia and Polycythemia Vera patients with arterial hypertension

Essential Thrombocythemia (ET) and Polycythemia Vera (PV) are chronic myeloproliferative neoplasms (MPNs) characterized by thrombotic and hemorrhagic complications, leading to a high risk of disability and mortality. Although arterial hypertension was found to be the most significant modifiable cardiovascular (CV) risk factor in the general population, little is known about its role in MPNs as well as a possible role of renin-angiotensin system inhibitors (RASi) in comparison with other anti-hypertensive treatments. We investigated a large cohort of 404 MPN adult patients, 133 diagnosed with PV and 271 with ET. Over half of the patients (53.7%) reported hypertension at MPN diagnosis. The 15-year cumulative incidence of thrombotic-adverse events (TAEs) was significantly higher in patients with hypertension (66.8 ± 10.3% vs 38.5 ± 8.4%; HR = 1.83; 95%CI 1.08-3.1). Multivariate analysis showed that PV diagnosis and hypertension were independently associated with a higher risk of developing TAEs (HR = 3.5; 95%CI 1.928-6.451, p < 0.001 and HR = 1.8; 95%CI 0.983-3.550, p = 0.05, respectively). In multivariate analysis, the diagnosis of PV confirmed a significant predictive role in developing TAEs (HR = 4.4; 95%CI 1.92-10.09, p < 0.01), also considering only MPN patients with hypertension. In addition, we found that the use of RASi showed a protective effect from TAEs both in the whole cohort of MPN with hypertension (HR = 0.46; 95%CI 0.21-0.98, p = 0.04) and in the subgroup of thrombotic high-risk score patients (HR = 0.49; 95%CI 0.24-1.01, p = 0.04). In particular, patients with ET and a high risk of thrombosis seem to benefit most from RASi treatment (HR = 0.27; 95%CI 0.07-1.01, p = 0.03). Hypertension in MPN patients represents a significant risk factor for TAEs and should be adequately treated.

[Role and clinical significance of MUC4 gene mutations in thrombotic events in patients with classic paroxysmal nocturnal hemoglobinuria]

Objective: This study aimed to investigate the role and clinical significance of MUC4 gene mutations in thrombotic events in patients with classic paroxysmal nocturnal hemoglobinuria (PNH) patients. Methods: A retrospective analysis was conducted on the clinical data and gene sequencing results of 45 patients with classic PNH admitted to the Department of Hematology, Tianjin Medical University General Hospital, from June 2018 to February 2022. MUC4 gene mutations in patients with classic PNH were summarized, and the risk factors for thrombotic events in these patients were analyzed. Additionally, the effects of MUC4 gene mutations on the cumulative incidence and survival of thrombotic events in patients with classic PNH were determined. Results: The detection rate of MUC4 gene mutations in patients with classic PNH who experienced thrombotic events (thrombotic group) was 68.8% (11/16), which was significantly higher than that in the non-thrombotic group [10.3% (3/29) ] (P<0.001). All mutations occurred in exon 2. MUC4 mutation (OR=20.815, P=0.010) was identified as an independent risk factor for thrombotic events in patients with classic PNH. The cumulative incidence of thrombotic events was 78.6% (11/14) in the MUC4 gene mutation group (mutation group) and 16.1% (5/31) in the non-mutation group, showing a statistically significant difference between the two groups (P<0.001). Survival analysis showed a lower overall survival (OS) rate in the thrombotic group compared with that in the non-thrombotic group [ (34.4±25.2) % vs. (62.7±19.3) % ] (P=0.045). The OS rate of patients was (41.7±29.9) % in the mutation group and (59.1±18.3) % in the non-mutation group (P=0.487) . Conclusion: MUC4 gene mutations are associated with an increased incidence of thrombotic events in classic PNH patients, highlighting their role as independent risk factors for thrombosis in this population. These mutations can be considered a novel predictive factor that aids in evaluating the risk of thrombosis in patients with classic PNH.

Superiority of bivalirudin over heparin anticoagulation therapy for extracorporeal membrane oxygenation? Too early to draw conclusions

Background

We aimed to compare the efficacy and safety of bivalirudin versus heparin as the anticoagulant in patients undergoing extracorporeal membrane oxygenation (ECMO).

Methods

We conducted a search in PubMed, Embase and the Cochrane Library for all the studies in which bivalirudin was compared to heparin as the anticoagulant for ECMO. Efficacy outcomes were defined as the time to reach therapeutic levels, time within therapeutic range (TTR), thrombotic events, circuit thrombosis, circuit exchanges. Safety outcomes were reported as heparin-induced thrombocytopenia (HIT), major bleeding events, minor bleeding events. Other outcomes included hospital length of stay (LOS), ICU LOS, mortality, 30-day mortality and in-hospital mortality.

Results

Ten studies with 1091 patients were included for meta-analysis. A significant reduction in thrombotic events [OR 0.51, 95%CI 0.36,0.73, p = 0.0002, I² = 0%], major bleeding events [OR 0.31, 95%CI 0.10,0.92, p = 0.04, I² = 75%] and in-hospital mortality [OR 0.63, 95%CI 0.44,0.89, p = 0.009, I² = 0%] treated with bivalirudin were found compared with heparin. There were no significant differences between groups regarding the time to reach therapeutic levels [MD 3.53, 95%CI -4.02,11.09, p = 0.36, I² = 49%], TTR [MD 8.64, 95%CI -1.72,18.65, p = 0.10, I² = 77%], circuit exchanges [OR 0.92, 95%CI 0.27,3.12, p = 0.90, I² = 38%], HIT [OR 0.25, 95%CI 0.02,2.52, p = 0.24, I² = 0%], minor bleeding events [OR 0.93, 95%CI 0.38,2.29, p = 0.87, I² = 0%], hospital LOS [MD -2.93, 95%CI -9.01,3.15, p = 0.34, I² = 45%], ICU LOS [MD -4.22, 95%CI -10.07,1.62, p = 0.16, I² = 0%], mortality [OR 1.84, 95%CI 0.58,5.85, p = 0.30, I² = 60%] and 30-day mortality [OR 0.75, 95%CI 0.38,1.48, p = 0.41, I² = 0%].

Conclusion

Bivalirudin probably be a potential choice for ECMO anticoagulation. However, based on the included studies' limitation, the superiority of bivalirudin over heparin for anticoagulation in the ECMO population still require further prospective randomized controlled studies before a definite conclusion.

Real-world treatments and thrombotic events in polycythemia vera patients in the USA

Polycythemia vera (PV) is a myeloproliferative neoplasm associated with increased risk of thrombotic events (TE) and death. Therapeutic interventions, phlebotomy and cytoreductive medications, are targeted to maintain hematocrit levels < 45% to prevent adverse outcomes. This retrospective observational study examined medical and pharmacy claims of 28,306 PV patients initiating treatment for PV in a data period inclusive of 2011 to 2019. Study inclusion required ≥ 2 PV diagnosis codes in the full data period, at least 1 year of PV treatment history, and ≥ 1 prescription claim and medical claim in both 2018 and 2019. Patients having ≥ 2 hematocrit (HCT) test results in linked outpatient laboratory data (2018-2019) were designated as the HCT subgroup (N = 4246). Patients were characterized as high- or low-risk at treatment initiation based on age and prior thrombotic history. The majority of patients in both risk groups (60% of high-risk and 83% of low-risk) initiated treatment with phlebotomy monotherapy, and during a median follow-up period of 808 days, the vast majority (81% low-risk, 74% high-risk) maintained their original therapy during the follow-up period. Hematocrit control was suboptimal in both risk groups; 54% of high-risk patients initiating with phlebotomy monotherapy sometimes/always had HCT levels > 50%; among low-risk patients, 64% sometimes/always had HCT levels above 50%. Overall, 16% of individuals experienced at least 1 TE subsequent to treatment initiation, 20% (n = 3920) among high-risk and 8% (n = 629) among low-risk patients. This real-world study suggests that currently available PV treatments may not be used to full advantage.

Association between liver fibrosis and thrombotic or bleeding events in acute coronary syndrome patients

BACKGROUND

The prognostic implication of liver fibrosis in acute coronary syndrome (ACS) patients are scarce. We sought to evaluate whether liver fibrosis scores (LFS) were associated with thrombotic or bleeding events in patients with acute coronary syndrome.

METHODS

We included 6386 ACS patients who underwent percutaneous coronary intervention (PCI). This study determined liver fibrosis with aspartate aminotransferase to platelet ratio index (APRI), aspartate aminotransferase to alanine aminotransferase ratio (AST/ALT ratio), Forns score, and nonalcoholic fatty liver disease fibrosis score (NFS). The primary endpoint was major adverse cardiac and cerebrovascular events (MACCE), a composite of all-cause mortality (ACM), myocardial infarction (MI), and ischemic stroke (IS).

RESULTS

During the follow-up, 259 (4.06%) MACCE and 190 (2.98%) bleeding events were recorded. As a continuous variable or a categorical variable stratified by the literature-based cutoff, LFS was positively associated with MACCE (p > 0.05) but not with bleeding events. Compared with subjects with low APRI scores, AST/ALT ratio scores, Forns scores, and NFS scores, subjects with high scores had a 1.57- to 3.73-fold increase risk of MACCE after adjustment (all p < 0.05). The positive relationship between LFS and MACCE was consistent in different subgroups.

CONCLUSIONS

In ACS patients, increased LFS predicted an elevated risk of thrombotic events but not bleeding. LFS may contribute to thrombotic risk stratification after ACS.

Thrombotic complications after radiofrequency and cyanoacrylate endovenous ablation: Outcomes of a multicenter real-world experience

OBJECTIVE

Chronic venous insufficiency (CVI) affects >40% of the U.S. population; thus, intervention for symptomatic venous disease comprises a large portion of many vascular practices. The treatment of superficial CVI has evolved from open surgical treatment to minimally invasive endovenous closure, including both thermal and nonthermal techniques. Thrombotic complications of thermal ablation have been well reported, with an overall complication rate of <2%. However, a paucity of high-powered, real-world data is available on the thrombotic outcomes of nonthermal techniques. In the present study, we compared the incidence of endovenous heat-induced thrombosis (EHIT) and endovenous glue-induced thrombosis (EGIT) in a large cohort of patients with CVI.

METHODS

A retrospective review was conducted at two tertiary-level institutions of patients who had undergone superficial endovenous ablation from 2018 to 2021. The patient demographics, comorbidities, and periprocedural outcomes were collected through medical record review. A Caprini risk assessment model score was assigned using the information available from the electronic medical records. The patients were categorized by procedure type (ClosureFast [Medtronic Inc, Minneapolis, MN] radiofrequency ablation [RFA] vs VenaSeal [Medtronic Inc] cyanoacrylate glue closure [CAG]). The primary end point was the incidence of EHIT or EGIT. The secondary end point was the incidence of deep vein thrombosis and/or pulmonary embolism.

RESULTS

A total of 803 patients had undergone 1096 procedures during the study period. Their mean age was 62 ± 15 years, and 67% were women. Of the 1096 procedures, 700 were RFA and 396 were CAG procedures, with a combined closure rate of 98% by postprocedure duplex ultrasound at 7 days. The average Caprini score was 5.2 ± 1.8 (RFA, 5.0; vs CAG, 5.4; P < .001). The incidence of EHIT and EGIT was 1.9% and 1.3%, respectively (P = .57). The deep vein thrombosis rate was 0.1% in the RFA cohort and 0.3% in the CAG cohort (P = .81). A comparative analysis of thermal vs nonthermal techniques was performed. A univariate analysis of the risk factors for EHIT and EGIT revealed no significant factors predisposing to thrombotic events.

CONCLUSIONS

The results from the present study have demonstrated the safety of RFA and CAG closure techniques for CVI, with lower thrombotic rates than previously reported. Further work might help to identify how these results can be achieved across all venous ablative techniques for CVI, even for patient populations with advanced venous disease and possibly a greater than average risk of thrombotic events.

COVID-19 Related Thrombotic Complications Experience Before and During Delta Wave

OBJECTIVE

Hypercoagulability and thrombotic complications seen in SARS-CoV-2 patients, as well as the associated pathophysiology, have been reported extensively. However, there is limited information regarding the factors related to this phenomenon and its association with the COVID-19 delta variant.

METHODS

A retrospective review including patients admitted to a tertiary center with a COVID-19 positive test and at least one acute thrombotic event confirmed by imaging between June 2020 and August 2021 was performed. We compared the rates of thrombotic events in patients with COVID-19 before and during the Delta peak. We also analyzed the association of the thrombotic complications with demographic characteristics, comorbidities, anticoagulation strategies, and prothrombotic markers while describing other complications secondary to COVID-19 infection.

RESULTS

Out of 964 patients admitted with COVID-19 diagnosis, 26.5% (n=256) had a thrombotic event evidenced by ultrasound (US) or computerized tomography (CT) scan. Venous thromboembolism was found in 60% (n=153), arterial thrombosis in 23% (n=60), and both venous and arterial thromboses in 17% (n=17) of the study cohort. Of all patients, 94% were not vaccinated. Delta variant wave patients (DW) had thrombotic episodes in 34.7% (n=50/144) of cases compared to 25% (n=206/820) of non-Delta wave (NDW) patients, posing an estimated risk 1.36 times higher in patients infected with COVID-19 during the DW than NDW. Overall, DW subjects were significantly younger (p<0.001) with lower BMI (p=0.021) compared to NDW patients. Statistical analyses showed African American patients were more likely to have arterial thrombosis compared to the other groups when testing positive for COVID-19 (OR: 1.78 [CI: 1.04 - 3.05], p=0.035), whereas immunosuppressed patients had less risk of arterial thrombosis (OR: 0.38 [CI: 0.15 - 0.96], p=0.042). Female gender (OR: 2.15 [CI: 1.20 - 3.85]. p=0.009) and patients with active malignancy (OR: 5.99 [CI: 2.14 - 16.78]. p=0.001) had an increased risk of having multiple thrombotic events at different locations secondary to COVID-19.

CONCLUSION

COVID-19 infection is associated with elevated rates of thrombotic complications and an especially higher risk in patients infected during the Delta variant peak. We highlight the importance of vaccination and the development of new anticoagulation strategies for COVID-19 patients with additional hypercoagulable risk factors to prevent thrombotic complications caused by this disease.

Thrombotic events following Covid-19 vaccines compared to Influenza vaccines

IMPORTANCE

The actual risk of thrombotic events after Covid-19 vaccination is unknown.

OBJECTIVE

To evaluate the risk of thrombotic events after Covid-19 vaccination.

DESIGN

Retrospective cohort study which included consecutive adult patients vaccinated with the first dose of Covid-19 vaccine between January 1 and May 30, 2021, and a historic control group, defined as consecutive patients vaccinated with influenza vaccine between March 1 and July 30, 2019.

SETTING

Hospital Italiano de Buenos Aires, a tertiary hospital in Argentina.

PARTICIPANTS

Non-Hospitalized Adults vaccinated with the first dose of a Covid-19 vaccine.

EXPOSURE

Vaccination with Covid-19 vaccines available during the study period: Gam-COVID-Vac (Sputnik), ChAdOx1 nCoV-19 (AstraZeneca/Oxford or Covishield), BBIBP-CorV (Beijing Institute of Biological Products) (Sinopharm). Active comparator group exposure was Influenza vaccine.

MAIN OUTCOME

Primary endpoint was cumulative incidence of any symptomatic thrombotic event at 30 days, defined as the occurrence of at least one of the following: symptomatic acute deep venous thrombosis (DVT); symptomatic acute pulmonary embolism (PE); acute ischemic stroke (AIS); acute coronary syndrome (ACS) or arterial thrombosis.

RESULTS

From a total of 29,985 adult patients who received at least a first dose of Covid-19 vaccine during study period and 24,777 who received Influenza vaccine in 2019, we excluded those who were vaccinated during hospitalization. We finally included 29,918 and 24,753 patients respectively. Median age was 73 years old (IQR 75-81) and 67% were females in both groups. Thirty six subjects in the Covid-19 vaccination group (36/29,918) and 15 patients in the Influenza vaccination group (15/24,753) presented at least one thrombotic event. The cumulative incidence of any thrombotic event at 30 days was 12 per 10,000 (95%CI 9-17) for Covid-19 group and 6 per 10,000 (95%CI 4-10) for Influenza group (p-value=0.022).

CONCLUSIONS AND RELEVANCE

This study shows a significant increase in thrombotic events in subjects vaccinated with Covid-19 vaccines in comparison to a control group. The clinical implication of these findings should be interpreted with caution, in light of the high effectiveness of vaccination and the inherent risk of thrombosis from Covid-19 infection itself.

Topical administration of tranexamic acid in elderly patients undergoing short femoral nailing for intertrochanteric fracture: A randomised controlled trial

INTRODUCTION

Topical application of tranexamic acid (TXA) has been proposed as an alternative to intravenous administration to reduce perioperative bleeding in orthopaedic surgery. The purpose of this randomised controlled trial was to evaluate the efficacy and safety of 1 g topically applied TXA in patients undergoing fixation of intertrochanteric hip fractures by short femoral nailing.

METHODS

A total of 121 patients were enrolled between May 2018 and January 2020. Patients were randomly allocated (1:1) to receive either 10 mL (1 g) of TXA or 10 mL of normal saline (NS) injected through the subfascial drain following wound closure. Total blood loss, total drain output and blood transfusion requirements up to postoperative day 3 were recorded. Rates of thromboembolic complications and mortality up to 90 days postoperatively were also compared.

RESULTS

There was no statistically significant difference in total blood loss, total drain output or proportion of patients requiring transfusions. Median total blood loss was 1.088 L (IQR: 0.760-1.795) in the TXA group and 1.078 L (IQR: 0.797-1.722) in the NS group (P = .703). Median total drain output was 60 mL (IQR: 40-140) in the TXA group and 70 mL (IQR: 30-168) in the NS group (P = .696). Blood transfusions were administered in 29 patients (47.5%) in the TXA group and 27 patients (45.0%) in the NS group (P = .782). There was also no difference in frequency of thrombotic complications or mortality within 90 days. There were five thrombotic events in the TXA group and four in the NS group (P = .751). The 90-day mortality rate was 6.6% (4 patients) in the TXA group and 3.3% (2 patients) in the NS group (P = .680).

CONCLUSION

A 1 g dose of topically administered TXA did not produce any difference in blood loss, transfusion requirements, thromboembolic complications, or 90-day mortality. Future trials may consider the effect of larger doses in patients undergoing hip fracture fixation surgery.

Effect of tranexamic acid on thrombotic events and seizures in bleeding patients: a systematic review and meta-analysis

BACKGROUND

Tranexamic acid (TXA) reduces surgical bleeding and reduces death from bleeding after trauma and childbirth. However, its effects on thrombotic events and seizures are less clear. We conducted a systematic review and meta-analysis to examine the safety of TXA in bleeding patients.

METHODS

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled trials from inception until June 1, 2020. We included randomized trials comparing intravenous tranexamic acid and placebo or no intervention in bleeding patients. The primary outcomes were thrombotic events, venous thromboembolism, acute coronary syndrome, stroke and seizures. A meta-analysis was performed using a random effects model and meta-regression analysis was performed to evaluate how effects vary by dose. We assessed the certainty of evidence using the grading of recommendations, assessment, development and evaluations (GRADE) approach.

RESULTS

A total of 234 studies with 102,681 patients were included in the meta-analysis. In bleeding patients, there was no evidence that TXA increased the risk of thrombotic events (RR = 1.00 [95% CI 0.93-1.08]), seizures (1.18 [0.91-1.53]), venous thromboembolism (1.04 [0.92-1.17]), acute coronary syndrome (0.88 [0.78-1.00]) or stroke (1.12 [0.98-1.27]). In a dose-by-dose sensitivity analysis, seizures were increased in patients receiving more than 2 g/day of TXA (3.05 [1.01-9.20]). Meta-regression showed an increased risk of seizures with increased dose of TXA (p = 0.011).

CONCLUSION

Tranexamic acid did not appear to increase the risk of thrombotic events in bleeding patients. However, because there may be dose-dependent increase in the risk of seizures, very high doses should be avoided.

Epidemiologic study of patients with thrombotic events referred to a tertiary hospital in Southern Iran

Background and aim

Thromboembolic events mainly occur in older age is related with high morbidity and mortality, and considerable health-care costs particularly in developing countries. Both arterial and venous thromboembolism has known risk factors such as hyperlipidemia, obesity, diabetes, cancer, major surgery, central catheter. We aimed to evaluate the occurrence of thrombotic events and related risk factors in a group of Iranian patients.

Methods

In this cross-sectional study, all patients (n = 99) who were complicated by thrombotic events referred to the Hematology Research Center of Shiraz University of Medical Sciences were investigated from 2015 to 2017, in Shiraz, Southern Iran. Data were collected from their medical records by a designed data gathering form.

Results

The median age of the occurrence of thrombosis was 51 (IQR: 31) years. From all thrombotic events 52.5% occurred in females. Venous thrombosis was more prevalent than arterial (61.6% vs. 38.4%). Hypertension, diabetes mellitus and ischemic heart disease were the most associated disease with thrombosis. Most of the patients (79.8%) had no episodes of relapse and the occurrence of relapse had no significant relationship with thrombophilia and underlying disease. Acceptable response rate for warfarin therapy was achieved in 46.5% with 5 mg and 43.4% with 5–7.5 mg.

Conclusion

Knowing the frequency and risk factors for thrombotic events lead to timely diagnosis and management of thrombosis. Atrial fibrillation and valvular rheumatic heart disease are the most common risk factors of thrombosis in our study showing prophylaxis is necessary in high-risk patients.

Platelet distribution width is highly associated with thrombotic events in primary antiphospholipid syndrome

OBJECTIVE

Platelet activation is a possible pathogenic process contributing to thromboembolism in antiphospholipid syndrome (APS), and platelet distribution width (PDW) is associated with platelet activation. The objective of this study was to evaluate the association between platelet indices and thrombotic events in patients with primary APS.

METHODS

This single-center cross-sectional study included 207 consecutive patients with APS treated at our institution between 2010 and 2019. Results of blood tests were recorded retrospectively from medical records.

RESULTS

Of the included patients, 135 (65.2%) were female and 72 (34.8%) were male. They were classified into thrombotic (n = 150) or non-thrombotic (n = 57) groups. PDW, mean platelet volume, and large platelet ratio were significantly higher in the thrombotic group. In univariate logistic analysis, PDW was significantly associated with an increased odds of thrombosis [odds ratio (OR) 1.554, 95% confidence interval (CI) 1.289-1.873, p<0.001]. In multivariate logistic analysis, PDW and positive lupus anticoagulant (LA) were risk factors for thrombosis. Receiver operating characteristic analysis showed that PDW, combined with a positive LA, was a reliable indicator of thrombosis, with an area under the curve of 0.796 (95% CI 0.728-0.864). The optimal cutoff value for PDW was 12.4 fl, with a sensitivity of 72.0% and specificity of 77.2%. Multivariate logistic regression of PDW tertiles showed that the odds of thrombosis increased abruptly in the highest tertile.

CONCLUSION

This study confirmed the association between PDW and thrombotic events in APS patients, supporting the theory that platelet activation is a crucial mechanism of thrombosis in APS. Key Points • This study is the first to discuss the correlation between PDW and thromboses in patients with APS. • This study provides evidence of the important role of platelet activation in the pathogenesis of APS.

Risk factors of thrombosis in Chinese subjects with acute promyelocytic leukemia

BACKGROUND

Acute promyelocytic leukemia (APL) is a special type of acute myeloid leukemia Thrombosis is at increased risk complication in patients with this disease. However, the risk factors of thrombosis related to Chinese APL patients are not fully understood.

METHODS

In this study, clinical and laboratory data of 44 consecutively Chinese APL patients were collected and analyzed.

RESULTS

One arterial and 6 venous thrombosis occurred in 44 patients, including 22 males and 22 females, with a median age of 44 years (range from 18 to 74 years). The ratio of male and female gender, age, white blood cell count, hemoglobin, platelets, disease risk stratification, CD2, Khorana score, differentiation syndrome (DS) and gene mutation related to prognosis of APL, including DNMT3A, TET2, IDH1, IDH2, NRAS and ASXL1 in the two groups with and without thrombosis were not statistically significant. The detection rate of PAI-1 genotype 4G4G was 71.4% (5/7) in 7 patients with thrombosis, while the detection rate of PAI-1 genotype 4G4G in 37 patients without thrombosis was 8.1% (3/37). The differences between the two groups in WT-1 (P = 0.01), PAI-1 4G4G (P = 0.0009), bcr3 (P = 0.027), CD15 (P = 0.005), and FLT3-ITD mutation (P = 0.0008) were statistically significant. Using multivariate analysis, the risk factors of venous thrombosis in APL were CD15 (P = 0.043), PAI-1 4G4G (P = 0.009), WT-1 (P = 0.043) and FLT3/ITD (P = 0.013), respectively.

CONCLUSION

Our results suggested the PAI-1 gene 4G4G type, CD15, WT-1 and FLT3-ITD mutations excluding DNMT3A, TET2, IDH1/2, NRAS and ASXL1 are risk factors of thrombotic events in Chinese APL patients.

Comparison of clinical features and outcomes in COVID-19 and influenza pneumonia patients requiring intensive care unit admission

BACKGROUND

Little is known in distinguishing clinical features and outcomes between coronavirus disease-19 (COVID-19) and influenza (FLU).

MATERIALS/METHODS

Retrospective, single-centre study including patients with COVID-19 or FLU pneumonia admitted to the Intensive care Unit (ICU) of Policlinico Umberto I (Rome). Aims were: (1) to assess clinical features and differences of patients with COVID-19 and FLU, (2) to identify clinical and/or laboratory factors associated with FLU or COVID-19 and (3) to evaluate 30-day mortality, bacterial superinfections, thrombotic events and invasive pulmonary aspergillosis (IPA) in patients with FLU versus COVID-19.

RESULTS

Overall, 74 patients were included (19, 25.7%, FLU and 55, 74.3%, COVID-19), median age 67 years (58-76). COVID-19 patients were more male (p = 0.013), with a lower percentage of COPD (Chronic Obstructive Pulmonary Disease) and chronic kidney disease (CKD) (p = 0.001 and p = 0.037, respectively) than FLU. SOFA score was higher (p = 0.020) and lymphocytes were significantly lower in FLU than in COVID-19 [395.5 vs 770.0 cells/mmc, p = 0.005]. At multivariable analysis, male sex (OR 6.1, p < 0.002), age > 65 years (OR 2.4, p = 0.024) and lymphocyte count > 725 cells/mmc at ICU admission (OR 5.1, p = 0.024) were significantly associated with COVID-19, whereas CKD and COPD were associated with FLU (OR 0.1 and OR 0.16, p = 0.020 and p < 0.001, respectively). No differences in mortality, bacterial superinfections and thrombotic events were observed, whereas IPA was mostly associated with FLU (31.5% vs 3.6%, p = 0.0029).

CONCLUSIONS

In critically ill patients, male sex, age > 65 years and lymphocytes > 725 cells/mmc are related to COVID-19. FLU is associated with a significantly higher risk of IPA than COVID-19.

Reduced macular vessel density in COVID-19 patients with and without associated thrombotic events using optical coherence tomography angiography

Purpose

Thrombotic events (TE) represent one of the major complications of SARS-CoV-2 infection. The objective is to evaluate vessel density (VD) and perfusion density (PD) by optical coherence tomography angiography (OCTA) in COVID-19 patients, and compare the findings with healthy controls. The secondary objective is to evaluate if there are differences in OCTA parameters between COVID-19 patients with and without associated TE.

Methods

Cross-sectional case–control study that included patients with laboratory-confirmed diagnosis of COVID-19 with and without TE related to the infection and age-matched healthy controls. Ophthalmological examination and OCTA were performed 12 weeks after diagnosis. Demographic data and medical history were collected. Macular OCTA parameters in the superficial retinal plexus were analyzed according to ETDRS sectors.

Results

Ninety patients were included, 19 (20%) COVID-19 patients with associated TE, 47 (49.5%) COVID-19 patients without TE, and 29 (30.5%) healthy controls. Fifty-three (55.7%) were male, mean age 54.4 (SD 10.2) years. COVID-19 patients presented significantly lower VD than healthy controls: central (p = 0.003), inner ring (p = 0.026), outer ring (p = 0.001). PD was also significantly decreased: outer ring (p = 0.003), full area (p = 0.001). No differences in OCTA parameters were found between COVID-19 patients with and without TE.

Conclusions

OCTA represents a promising tool for the in vivo assessment of microvascular changes in COVID-19. Patients with SARS-CoV-2 infection show lower VD and PD compared to healthy controls. However, no differences were found between COVID-19 when considering TE. Prospective studies are required to further evaluate the retinal microvascular involvement of SARS-CoV-2 and its impact on the vasculature of other organs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05186-0.

Anti-phospholipids antibodies and immune complexes in COVID-19 patients: a putative role in disease course for anti-annexin-V antibodies

Introduction

Besides distinctive respiratory and digestive hallmarks, COVID-19 has been recently associated with a high prevalence of pro-inflammatory and hypercoagulable states known as “COVID-19 Associated Coagulopathy” (CAC), corresponding to a worsening in patients’ conditions, whose causes are still to be elucidated. A link between anti-phospholipid antibodies (aPLs) and viral infections has long been suggested. APLs are assessed for anti-phospholipid syndrome (APS) diagnosis, characterized by thrombocytopenia, thrombosis, and coagulopathy. Furthermore, circulating immune complexes (CICs), arisen upon inflammatory responses and related immune dysregulation, can lead to endothelial cell damage and thrombotic complications.

Method

We performed an extended panel including IgG/IgM anti-cardiolipin, IgG/IgM anti-β2-glycoprotein-1, coupled with IgG/IgM anti-prothrombin, IgG/IgM anti-annexin-V on two COVID-19 patient groups (early and late infection time), and a negative control group. IgG CIC analysis followed to evaluate inflammatory status, through a possible complement system activation.

Results

Our results showed low positive case percentage in IgG/IgM anti-cardiolipin and IgG/IgM anti-β2-glycoprotein-1 assays (4.54%, 6.25%, and 4.55%; in early infection group, late infection group, and control group, respectively); few positive cases in IgG/IgM anti-prothrombin and IgG/IgM anti-annexin-V immunoassays; and no IgG CIC positivity in any patient.

Conclusions

In conclusion, our data show a low aPL prevalence, likely excluding an involvement in the pathogenesis of CAC. Interestingly, IgG/IgM anti-prothrombin and anti-annexin-V positive cases, detected in late infection group, suggest that aPLs could temporarily increase or could trigger a “COVID-19-induced-APS-like-syndrome” in predisposed patients.

Key Points •To our knowledge, anti-prothrombin (aPT) antibodies, anti-annexin-V antibodies and CICs in COVID-19 patients have not been reported in the scientific literature. •Lack of uniformity and the low percentage of aCL/aβ2GP1 positivity preclude a putative role in CAC pathogenesis. •IgG/IgM anti-prothrombin and IgG/IgM anti-annexin-V data show that distribution of positive case number increases in late infection patients, significantly in anti-annexin-V results, suggesting a possible role for these anti-phospholipid antibodies in disease course. •aPLs can arise transiently in some patients with critical illness and SARS-CoV-2 infection (disappearing in a few weeks), as well as in other genetically predisposed patients; they could trigger a “COVID-19-induced-APS-like-syndrome”.

Does subcutaneous administration of recombinant human erythropoietin increase thrombotic events in total hip arthroplasty? A prospective thrombelastography analysis

BACKGROUND

Anemia is one of severe complications in the perioperative period of total hip arthroplasty (THA). Erythropoietin (EPO) has been considered to improve patients' anemia state, but its efficiency and safety remains controversial.

METHODS

A total of 152 patients who underwent total hip arthroplasty from January 2017 to March 2019 were randomized to 2 groups. Recombinant human erythropoietin (rHu-EPO) group was treated with rHu-EPO subcutaneous injection 10000 IU after operation and once daily in the next week, while control group was treated with none extra treatment. Routine hematologic examination and thrombelastography (TEG) performed at different time point respectively. Doppler ultrasound for bilateral lower limbs was performed 1 day before surgery and 7 days after surgery. Auxiliary examination outcomes, blood transfusions outcomes, and postoperative complications were recorded as assessment indicators.

RESULTS

The difference in the relevant indexes of traditional coagulation and TEG values between two groups were not significantly. No significant difference was observed in the incidence of thromboembolism events and other complications between two groups during postoperative period. The amount of intraoperative blood loss was similar between the two groups. However, the postoperative use and dosage of allogeneic blood in the rHu-EPO group were lower than those in the control group. The hemoglobin and hematocrit level in the rHu-EPO group were higher than that in the control group after surgery.

CONCLUSION

Postoperative subcutaneous injection of rHu-EPO can improve hematological anemia-related parameters, reduce the use and dosage of allogeneic blood transfusions (ABTs), and has no significant influence on the formation of thrombosis and other complications in patients undergoing total hip arthroplasty in short term.

Thromboelastography findings in critically ill COVID-19 patients

The rate of venous and arterial thrombotic events among patients infected with severe acute respiratory syndrome coronavirus-2 (SAR-CoV-2) is high. This may be due to a hypercoagulable state induced by the severe inflammation that results from the SAR-CoV-2 infection. We aimed to determine hypercoagulable states' incidence based on thromboelastography study and its association with thrombotic events in critically ill patients with coronavirus disease 2019 (COVID-19). Fifty-two COVID-19 patients who had thromboelastography study were retrospectively included. All patients received pharmacologic thromboprophylaxis. The hypercoagulable state was observed in 16 patients (30.8%). Among them, maximum amplitude and a-angle were elevated in 75% and 25%, respectively. Reaction time and K were low in only 12.5% for both of them. Inflammatory and coagulation markers, as well as thromboprophylaxis regimens, were not associated with a hypercoagulable state. Fourteen patients (27%) experienced a total of 16 thrombotic events, including 8 (57%) deep venous thrombosis, 6 (43%) pulmonary embolism, and 2 (14.3%) arterial thrombosis. The hypercoagulable state was not significantly associated with thrombotic events. In summary, we observed a lower rate of hypercoagulable state on thromboelastography study in critically ill COVID-19 patients. Also, the hypercoagulable state was not associated with the occurrence of thrombotic events.

Characterization and timing of gastrointestinal bleeding in continuous flow left ventricular assist device recipients

BACKGROUND AND AIMS

Heart failure is one of the leading causes of morbidity and mortality in the United States. The advent of left ventricular assist devices (LVAD) has improved the survival and quality of life in patients with end stage heart failure. Gastrointestinal bleeding (GIb) remains one of the limitations of LVADs.

METHODS

A single center, retrospective review of records was performed for patients who underwent LVAD implantation between 2010 and 2015. All patients who survived more than 30 days were followed till March 2016 and are described below.

RESULTS

A total of 79 patients were included in the study. The rate of GIb was 34.1% (27 patients) with a mean time to bleed of 267 days. Older patients were more likely to bleed. Upper GI bleeding was the source of bleeding in 54% patients. Arteriovenous malformations (AVM) were the source of bleeding in 74% bleeders and 80% of these patients had de novo AVM formation. 14/27 (51%) patients had a re-bleeding event. Thrombotic events were 4.5 times more likely to occur in patients who also had a GI bleed.

CONCLUSIONS

GI bleeding in LVAD patients is common with the source of bleeding more commonly being in the upper GI tract. GI bleeding may occur as early as 10 days post procedure, despite previous negative screening endoscopies. There is an increased risk of thrombotic events in patients who have experienced a GI bleed.

Antithrombotic therapy with rivaroxaban in five patients with paroxysmal nocturnal haemoglobinuria and thrombotic events

Five patients with paroxysmal nocturnal haemoglobinuria and thrombotic complications under oral antithrombotic treatment with vitamin K antagonist were switched to receive the direct oral anticoagulant rivaroxaban an factor Xa inhibitor. In all five patients haematological and biochemical parameters and adverse events were evaluated for a period of twelve months. Therapy with rivaroxaban was well tolerated in all cases and one patient showed a significant reduction of bleeding and transfusion requirement. All patients obtained a significant reduction in days of hospitalization with a consequent improvement in their quality of life after rivaroxaban treatment.

Exploration of Bivalirudin Use during Percutaneous Coronary Intervention for High Bleeding Risk Patients with Chronic Total Occlusion

The safety and efficacy of bivalirudin during percutaneous coronary intervention (PCI) in high bleeding risk patients with chronic total occlusion lesions (CTO) has not been studied till date. The use of bivalirudin may increase the thrombotic events during CTO-PCI.Between May 2013 and April 2014, a total of 117 high bleeding risk patients with CTOs underwent PCI. Bivalirudin was used in 89 cases with different strategies, including standard usage, combination of heparin, and additional bolus of bivalirudin on the basis of standard usage. The clinical characteristics, procedural details and antithrombotic strategies were assessed, and the bleeding and ischemic events were evaluated. The first 7 of 9 patients with standard application of bivalirudin exhibited acute thrombogenesis in the procedure. Heparin was then added in decreasing amounts in the next 8 patients wherein no thrombosis occurred; however, 2 patients had bleeding complications. The subsequent 72 patients were randomly assigned to the heparin bolus or additional bivalirudin bolus groups before the percutaneous transluminal coronary angioplasty (PTCA) was performed. The baseline clinical characteristics and procedure information were identical in both the groups. There were no ischemic and bleeding events in both the groups during the 6-month follow-up.Monotherapy with bivalirudin in CTO-PCI should be treated with caution, as the potential risk of thrombogenesis may be due to the long procedure time, the frequent change of equipment and temporary blood flow convection. Combination of heparin or an additional bolus of bivalirudin before PTCA was observed to be likely to decrease the incidence of thrombogenesis.

Continuing versus discontinuing antiplatelet drugs, vasodilators, and/or cerebral ameliorators on perioperative total blood loss in total knee arthroplasty without pneumatic tourniquet

Background

Although studies have supported the utility of perioperative continuation of antiplatelet drugs, vasodilators, and cerebral ameliorators in most procedures, no study compared total volume of blood loss after total knee arthroplasty (TKA) in patients continuing and discontinuing these drugs.

Methods

We retrospectively reviewed 266 consecutive patients undergoing TKA, and included 67 patients (25.2%) taking antiplatelet drugs, vasodilators, or cerebral ameliorators in this study. All TKAs were performed without a pneumatic tourniquet. The primary outcome was perioperative total blood loss calculated from blood volume and change in hemoglobin. As subgroup analysis, we compared perioperative total blood loss in patients taking antiplatelet drugs.

Results

There was no significant difference between the continuing group (n = 38) and discontinuing group (n = 29) in terms of the perioperative total blood loss (1025 ± 364 vs 1151 ± 327 mL, respectively; mean difference 126 mL; 95% confidence interval -45 to 298 mL; P = .15). No major bleeding or thrombotic events occurred in either group until postoperative 3-month follow-up. In patients taking antiplatelet drugs (n = 51), no significant difference was observed in the total blood loss between the continuing group (n = 30) and discontinuing group (n = 21) (1056 ± 287 vs 1151 ± 305 mL, respectively; mean difference 95 mL; 95% confidence interval -75 to 264 mL; P = .27).

Conclusions

No significant differences in terms of perioperative total blood loss were observed between patients continuing and discontinuing study drugs. Continuing these drugs may be preferable in the perioperative period of TKA.

Blood coagulation system in patients with chronic kidney disease: a prospective observational study

OBJECTIVES

Thromboembolic events are the major factor affecting the prognosis of patients with chronic kidney disease (CKD). Haemostatic alterations are possible causes of these complications, but their roles remain poorly characterised. In the prospective observational study, we investigated the entire coagulation process in patients with CKD to elucidate the mechanisms of their high thromboembolic risk.

METHODS

A total of 95 patients with CKD and 20 healthy controls who met the inclusion criteria were consecutively recruited from September 2015 to March 2016. The platelet count, platelet aggregation, von Willebrand factor antigen (vWF:Ag), vWF ristocetin cofactor activity (vWF:RCo), fibrinogen, factor V (FV), FVII, FVIII, antithrombin III, protein C, protein S, D-dimer, standard coagulation tests and thromboelastography were measured in patients with CKD and controls. Associations between the estimated glomerular filtration rate (eGFR) and haemostatic biomarkers were tested using multivariable linear regression.

RESULTS

The adjusted and unadjusted levels of vWF:Ag, vWF:RCo, fibrinogen, FVII, FVIII and D-dimer were significantly higher in patients with CKD than that in the healthy controls, and were elevated with CKD progression. However, after adjustment for baseline differences, platelet aggregation and thromboelastography parameters showed no significant differences between patients with CKD and healthy controls. In the correlation analysis, vWF:Ag, vWF:RCo and FVIII were inversely associated with eGFR (r=-0.359, p<0.001; r=-0.391, p<0.001; r=-0.327, p<0.001, respectively). During the 1-year of follow-up, one cardiovascular event occurred in patients with CKD 5 stage, whereas no thromboembolic event occurred in the CKD 3 and 4 and control groups.

CONCLUSIONS

Patients with CKD are characterised by endothelial dysfunction and increased coagulation, especially FVIII activity. The abnormal haemostatic profiles may contribute to the elevated risk of thrombotic events but further longer-term study with large samples is still required to more precisely determine the relationship between the elevation of procoagulant factors and clinical outcomes.

Thrombotic events as incidental finding on computed tomography in intensive care unit patients

INTRODUCTION

Intensive care unit (ICU) patients are a risk group to develop thrombosis and/or thromboembolism. The purpose of this study was to analyze the frequency and localization of clinically silent thrombotic events (TE) detected on CT.

MATERIALS AND METHODS

From 2006 to 2013 a total of 370 patients from the ICU of our university clinic were investigated by postcontrast CT. In all cases CT was performed for detecting septic foci. There were 135 women and 235 men. CT scans included cervical, thoracic, abdominal, and pelvic regions. CT images of all patients were re-interpreted by 2 radiologists by consensus. Only thromboses detected for the first time on CT were included into the analysis. Collected data were evaluated by means of descriptive statistics. Frequencies and localizations of TE in surgical and non surgical patients were analyzed by Chi-square test. Significance level was p<0.05.

RESULTS

In 31.9% several TE were diagnosed. There were venous thrombosis (89.8%), cardiac thrombus (2.6%), and pulmonary embolism (7.6%). More often jugular veins were affected followed by brachiocephalic veins, and iliac veins. The frequency of TE in surgical patients was 31.1%, and 32.1% in non surgical patients. Patients after surgery had more often thrombosis of extremities veins in comparison to non surgical patients. In 61.9% of all TE the identified thrombotic complications were not diagnosed at the time of CT investigations.

CONCLUSION

TE can be identified in 31.9% of ICU patients as incidental finding on CT. There were venous thromboses, pulmonary embolism, and cardiac thrombus. Most frequently neck and thoracic veins were affected. 61.9% of all TE were not diagnosed at the time of CT investigations. Radiologists should check carefully CT scans for presence of different TE.

Cardiovascular involvement in inflammatory bowel disease: Dangerous liaisons

Increasing evidence of a link between inflammatory bowel disease (IBD) and adverse cardiovascular events has emerged during the last decade. In 2014, an important number of meta-analyses and cohort studies clarified the subtle dangerous liaisons between gut inflammation and cardiovascular pathology. The evidence suggests that patients with IBD have a significantly increased risk of myocardial infarction, stroke, and cardiovascular mortality, especially during periods of IBD activity. Some populations (e.g., women, young patients) may have an even greater risk. Current effective treatment of IBD is aimed at disease remission and seems to reduce cardiovascular risk in these patients. A beneficial effect was demonstrated for salicylates, but not for steroids or azathioprine. tumor necrosis factor-α antagonists, which are highly effective in the reduction of inflammation and in the restoration of the digestive mucosa, lead to conflicting cardiovascular effects, as they seem to reduce the risk for ischemic heart disease but increase the rate of cerebrovascular events. Future supplemental treatment strategies that may reduce the atherothrombotic risk during periods of IBD activity should be explored.

Thrombotic events in acute promyelocytic leukemia

INTRODUCTION

Thrombotic events (TE) appear to be more common in acute promyelocytic leukemia (APL) than in other acute leukemias, with reported prevalence ranging from 2 to 10-15%.

MATERIALS AND METHODS

We retrospectively analyzed the data on TE appearance in 63 APL patients.

RESULTS

TE occured in 13 (20.6%) cases, four arterial (6.3%) and nine venous (14.3%). TE were more frequently diagnosed after initiation of weekly D-dimer monitoring (7 TE during 20 months vs 6 during 76 months, P=0.032). Patients with and without venous thrombosis were significantly different regarding female/male ratio (P=0.046), PT (P=0.022), aPTT (P=0.044), ISTH DIC score (P=0.001), bcr3 (P=0.02) and FLT3-ITD (P=0.028) mutation. The most significant risk factor for venous TE occurrence in multivariate analysis was FLT3-ITD mutation (P=0.034). PAI-1 4G/4G polymorphism was five times more frequent in patients with venous TE than without it (P=0.05). Regarding risk factors for arterial TE we failed to identify any.

CONCLUSIONS

We have demonstrated that APL-related TE rate is higher than previously reported and that weekly D-dimer monitoring might help to identify patients with silent thrombosis. Moreover, our study suggests a possible relationship between venous TE occurrence and several laboratory findings (PT, aPTT, ISTH DIC score, bcr3 isoform, FLT3-ITD mutation and PAI 4G/4G). Prophylactic use of heparin might be considered in patients with ISTH DIC score<5, bcr3 isoform, FLT3-ITD mutation and PAI 4G/4G.

Should patients taking aspirin for secondary prevention continue or discontinue the medication prior to elective, abdominal surgery? Best evidence topic (BET)

This best evidence topic was investigated according to a described protocol. The question asked was: should patients on acetylsalicylic acid (ASA) for secondary prevention stop or continue the medication prior to elective, abdominal surgery. Using the reported search 826 papers were found of which five represented the best evidence to answer the clinical question. The strongest evidence was from a randomized controlled trial (RCT) specifically looking at elective abdominal surgery, which showed no statistically significant difference between ASA continuation and discontinuation in terms of haemorrhagic or thrombotic events. Two other RCT's examined elective non-cardiac surgery but only a minor proportion (20.6% and 23.6%) of patients underwent abdominal surgery and data were unavailable regarding adverse events in these patients. However, one of these trials did show a 7.2% absolute risk reduction in postoperative cardiac adverse events when ASA was continued. One prospective cohort study found no difference between ASA maintenance and cessation except for longer duration of surgery in the ASA continuation group. Finally one recent retrospective cohort study revealed similar bleeding rates between ASA-treated and non-ASA-treated patients but increased cardiac complication rates in the ASA group. Only two studies compared continuation versus discontinuation of ASA, while the remaining three looked at patients on ASA versus those not on ASA. This heterogeneity in methodology makes it difficult to draw justifiable conclusions from the data. However, it appears that continuing ASA isn't associated with excessive bleeding. Further adequately powered trials with well-defined end points are needed to answer this important clinical question.

Escalating doses of C1 esterase inhibitor (CINRYZE) for prophylaxis in patients with hereditary angioedema

BACKGROUND

Nanofiltered C1 inhibitor (human) is approved in the United States for routine prophylaxis of angioedema attacks in patients with hereditary angioedema, a rare disease caused by a deficiency of functional C1 inhibitor.

OBJECTIVE

To assess the safety of escalating doses of nanofiltered C1 inhibitor (human) in patients who were not adequately controlled on the indicated dose (1000 U every 3 or 4 days).

METHODS

Eligible patients had >1 attack/month over the 3 months before the trial. Doses were escalated to 1500 U every 3 or 4 days for 12 weeks, at which point, the patients were evaluated. If treatment was successful (≤1 attack/mo) or at the investigator's discretion, the patients entered a 3-month follow-up period. The patients with an average of >1 attack/month were eligible for further escalation to 2000 U and then 2500 U.

RESULTS

Twenty patients started at 1500 U; 13 were escalated to 2000 U, and 12 were escalated to 2500 U. Eighteen patients reported adverse events. Two patients reported 4 serious adverse events (cerebral cystic hygroma, laryngeal angioedema attack, anemia, and bile duct stone) that were considered by investigators to be unrelated to treatment. Notably, there were no systemic thrombotic events or discontinuations due to adverse events. Fourteen patients were treated successfully (70%), continued to the follow-up period at the investigator's discretion, or experienced a reduction in attacks of >1.0/month.

CONCLUSIONS

Dose escalation of nanofiltered C1 inhibitor (human) up to 2500 U was well tolerated and reduced attack frequency in the majority of patients.