Risks and treatment related aspects of COVID-19 infection in patients with ANCA-associated vasculitis

OBJECTIVE

Patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) require immunosuppressive therapy for disease control and relapse prevention and may be at risk for severe coronavirus disease 2019 (COVID-19). The study objective was to analyse risk factors and outcomes of COVID-19 in well-characterized AAV patients.

METHOD

Data were retrieved from March 2020 to May 2021 from medical records of AAV cohorts in Stockholm and Uppsala, Sweden. COVID-19 was confirmed by positive PCR test or by ELISA. Severe COVID-19 was defined as need for non-invasive ventilation, intensive care unit care, and/or death. Age, gender, ANCA antibody type, ongoing immunosuppressive medication, and estimated glomerular filtration rate were recorded.

RESULTS

The cohort comprised 310 AAV patients, of whom 29 (9%) were diagnosed with COVID-19. Four deaths were attributed to COVID-19. Fifteen patients (52%) were on prednisolone in the COVID-19 group and 130 (46%) in the non-COVID group, with significantly higher doses in COVID-19 patients (p < 0.01). Ongoing induction therapy was more prevalent in the COVID-19 group (p < 0.01). Severe COVID-19 was diagnosed in 9/29 (31%). Significant risk factors for severe COVID-19 were impaired kidney function (p = 0.01) and more intense immunosuppressive therapy (p = 0.02), with a trend for age (p = 0.07). Maintenance therapy with rituximab was not associated with severe COVID-19.

CONCLUSIONS

Our findings highlight risks and suggest that more attention should be given to optimal AAV treatment in a pandemic situation. They also emphasize the need for continued shielding, mitigation strategies, and effective vaccination of AAV patients.

POS0923 EXTRACELLULAR VESICLES AS POTENTIAL BIOMARKERS OF EARLY DISEASE STAGE IN SYSTEMIC SCLEROSIS

Background

Extracellular vesicles (EVs) are membrane-coated vesicles most often generated from the vasculature and circulating blood cells upon cell activation and during the early phase of apoptosis (1).

Objectives

To evaluate the concentration of different subpopulations of EVs in plasma from patients with SSc in relation to the disease duration and to the markers of endothelial injury.

Methods

Our study included 59 SSc patients (36 limited (lSSc) and 23 diffuse cutaneous subset (dSSc)) and 46 healthy age and gender matched controls subjects. Disease duration less than 3 years in patients with dSSc and less than 5 years in those with lSSc was considered as early disease stage. Clinical evaluation of patients was performed. EVs were analysed with flow cytometry after staining platelet poor plasma with fluorescent cell-specific monoclonal antibodies. The concentration of following phosphatidylserine-positive EVs (PS+ EVs) were analyzed: total EVs, endothelial EVs (EEVs; CD144+), platelet EVs (PEVs; CD42b+), monocytes EVs (LEVs; CD14+), EVs expressing ICAM1 (CD54+), VCAM1 (CD106+) and P selectin (CD62p+). Serum levels of ICAM1, VCAM1 and P selectin were determined with ELISA.

Results

Median disease duration of our cohort was 4 (0-29) years (early lSSc [20/36]: 2.5 (0-4.5) years; early dSSc [11/23]: 10 (1-30) months). All types of investigated EVs were significantly elevated in SSc patients compared to controls (p<0.05). Patients with early disease stage had significantly increased levels of all PS+EVs compared to HC (p<0.05). Moreover, the levels of EVs expressing ICAM1 and VCAM1 showed good validity in identifying patients with early disease stage (AUC 0.7, p<0.01). PEVs were increased in early dSSc compared to early lSSc, but the difference did not reach statistical significance (p=0.07). There was a correlation between serum levels and the levels of EVs expressing specific adhesion molecules (ICAM1: r=0.7, p<0.01; VCAM1: r=0.7, p<0.01; P selectin: r=-0.7, p<0.01), only within the group with early dSSc subtype of the disease. Further correlations were detected between ICAM1+EVs with either mRSS (r=0.07, p< 0.01) or EUSTAR activity index (r=0.07, p= 0.02) among patients with early dSSc.

Conclusion

Increased levels of circulating EVs of different cell origin were present in patients with early SSc. EVs expressing either ICAM1 or VCAM1 could be novel biomarkers of early disease. EVs expressing ICAM1 showed association with severity of skin involvement and disease activity in patients with early dSSc giving insight into their role in the pathogenesis of SSc.

References

[1]J Colic, M Matucci-Cerinic, S Guiducci and N Damjanov. Review: Microparticles in systemic sclerosis, targets or tools to control fibrosis: This is the question!. Journal of Scleroderma and Related Disorders. 2019; 5(34):239719831985735

Disclosure of Interests

None declared

AB0616 Myeloperoxidase (MPO) positive extracellular vesicles (EVs) expressing complement split products in Anti - Neutrophil Cytoplasmic Antibody (ANCA) -associated Vasculitis (AAV)

Background

Complement activation has a critical role for the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We have previously shown increased expression of complement split products C3a and C5a on myeloperoxidase (MPO) positive EVs (MPO+EVs) in plasma from AAV patients with kidney involvement compared to the patients with non-renal disease and the EV-levels correlated with disease activity (1).

Objectives

To investigate the expression of a larger set of complement components on circulating MPO+EVs in relation to disease activity and kidney involvement in patients with AAV.

Methods

Eighty-nine patients with AAV and 23 healthy controls were included. The concentration of MPO+EVs expressing complement split products C3a, C4d, C5a, terminal complement complex-TCC (C5b-9) or complement factor B (CFB) were analyzed from citrate plasma by flow cytometry. The assessment of vasculitis disease activity was performed using the Birmingham Vasculitis Activity Score (BVAS).

Results

In the AAV group, there were 47 males (52.8%), the median age was 56 years and 33 (37.1%) patients were anti-MPO-positive and 54 (60.7%) were anti-PR3-positive. Two patients were positive for both antibodies. Median disease duration for patients with active AAV (BVAS>0; n=81) was 4 days and for patients in remission (BVAS 0; n=8) 1259 days. 64% had kidney involvement (n=52). Highly active AAV (BVAS ≥12) was noted in 62 patients, of whom 49 patients had kidney involvement. Active disease (0<BVAS<12) was seen in 19 patients. AAV patients had significantly higher levels of MPO+, MPO+C3a+, MPO+C4d+ and MPO+TCC+ EVs compared to healthy controls (all p<0.001). Patients in remission had higher levels of MPO+, MPO+C4d+ and MPO+TCC+ EVs compared to healthy controls (all p≤0.001). There was a significant difference in levels of MPO+(p=0.02), MPO+C3a+(p<0.001), MPO+C4d+(p<0.001) and MPO+TCC+ EVs (p<0.001) in patients with kidney involvement compared with patients without (n=29) (Figure 1). For patients with BVAS>0 there was a weak correlation between MPO+, MPO+C3a+, MPO+C4d+, MPO+TCC+ EVs and BVAS. Kidney biopsies from 34 patients were classified according to histopathological class (2): crescentic (n=6), focal (n=18), mixed (n=6), sclerotic (n=4). The level of MPO+C4d+EVs was higher in the sclerotic type compared to focal (p=0.04, 95% CI [2.4–103.7]) and mixed (p=0.04, 95% CI [1.4–119.1]).

Conclusion

Levels of EVs expressing complement split products were generally increased in AAV patients and patients with kidney involvement had higher levels of total MPO+EVs exposing C3a, C4d or TCC compared with patients without suggesting a role in kidney AAV pathogenesis. Patients with sclerotic kidney histotype had higher levels of MPO+C4d EVs compared with focal and mixed subgroups pointing to that activation of the classical complement pathway may be of importance in severe forms of kidney AAV.

References

[1]Antovic A et al. J Rheumatol. 2020 May 1;47(5):714-721. doi: 10.3899/jrheum.181347. Epub 2019 Aug 1. PMID: 31371653.

[2]Berden AE et al. J Am Soc Nephrol. 2010 Oct;21(10):1628-36. doi: 10.1681/ASN.2010050477. Epub 2010 Jul 8. PMID: 20616173.

Disclosure of Interests

None declared

OP0059 PROFOUND ANTICOAGULANT EFFECTS OF INITIAL ANTIRHEUMATIC TREATMENTS IN EARLY RHEUMATOID ARTHRITIS PATIENTS: A NORD-STAR SPIN-OFF STUDY

Background

Patients with rheumatoid arthritis (RA) are at an increased risk of venous thromboembolism. Thus far, there have not been any comparative studies investigating the effects of initial antirheumatic treatments in (very) early RA patients.

Objectives

To assess the effects of different initial treatments on hemostatic parameters in patients with early RA.

Methods

NORD-STAR is an international, multicentre, open-label, assessor-blinded, phase 4 study where patients with newly diagnosed RA started methotrexate (MTX) and were randomised 1:1:1:1 to a) conventional treatment (either prednisolone tapered to 5mg/day, or sulfasalazine combined with hydroxychloroquine and intra-articular corticosteroids), b) certolizumab pegol, c) abatacept, d) tocilizumab1. This study is a spin-off from the main NORD-STAR study extensively investigating hemostatic system in 24 per protocol consecutive Dutch participants at baseline, 12 weeks and 24 weeks after the start of the treatment. Statistical analysis was done using paired samples t-test in SPSS version 28.

Results

The mean age of investigated patients was 51.8 (± 12.7) years and 58.3% were female. At baseline patients had an average DAS28 score of 4.6 (± 0.9) and had elevated levels of investigated coagulation biomarkers: Factor 1 + 2, fibrinogen, D-dimer and parameters of the two global hemostatic assays, i.e. endogenous thrombin potential (ETP) and overall hemostasis potential (OHP). These biomarkers decreased significantly at 12 and 24 weeks in patients in all groups (Table 1). Overall fibrinolytic potential (OFP) was decreased and clot lysis time (CLT) was prolonged at baseline, demonstrating impaired fibrinolytic activity in early RA. The reduction of coagulation parameters was significantly higher in biological treatment arms in comparison to the standard MTX treatment arm. In addition, tocilizumab was more effective compared to certolizumab and abatacept, (Figure 1), which was expected considering the direct inhibitory effect of this drug on the IL-6 synthesis and consequently the coagulation activation as well. After 24 weeks of treatment with methotrexate and tocilizumab, the average fibrinogen of patients was reduced by 63% vs 31% and 36% in the certolizumab and abatacept groups, respectively. The changes in DAS-28 and the changes in fibrinogen had a correlation of 0.385 which did not reach statistical significance.

Table 1.

Measurements are marked with * if p<0.05, ** if p<0.01 and *** if p<0.001

BaselineW12W24Factor 1 + 2 (pmol/L)270.25 (149.4)190.36 (108.6)**179.52 (85.3)***Fibrinogen (g/L)4.64 (1.5)3.61 (1.6)**2.63 (1.2)***D-dimer (mg/L)2.17 (3.0)0.33 (0.23)**0.29 (0.2)**OHP (Abs-sum)157.38 (64.9)120.62 (68.7)*100.49 (53.8)***OCP (Abs-sum)369.52 (58.8)305.04 (101.7)*275.91 (83.1)***OFP (%)57.97 (13.1)63.20 (12.7)*65.25 (11.4)***Lag time (s)304.5 (71.1)306.8 (71.8)312.7 (65.4)Slope0.07 (0.02)0.066 (0.03)0.094 (0.12)Max Abs1.17 (0.3)1.00 (0.4)*0.91 (0.3)**CLT (s)1405 (356)1317 (377)1231 (320)**ETP (nM*min)1480 (471)1395 (395)*1337 (429)*Peak (nM)231 (78)223 (68)223 (74)Lagtime (min)4.06 (2.1)3.28 (1.2)**2.87 (1.0)***ttPeak (min)7.40 (2.2)6.61 (1.5)*6.13 (1.4)**Figure 1.

Conclusion

Our results indicate an enhanced coagulation and fibrinolytic impairment in newly diagnosed RA patients. Effective antirheumatic treatments reduce this hemostatic imbalance, with significantly more pronounced effects of biologic drugs compared to conventional (MTX+glucocorticoids) treatment.

References

[1]Hetland M et al. BMJ. 2020

Disclosure of Interests

Bas Dijkshoorn: None declared, Aleksandra Antovic: None declared, Daisy Vedder: None declared, Anna Rudin: None declared, Dan Nordström Speakers bureau: Novartis, UCB, Consultant of: Abbvie, BMS, Lilly, Novartis, Pfizer, Roche, UCB, Björn Gudbjornsson Speakers bureau: Amgen and Novartis - not related to this work, Consultant of: Novartis - not related to this work, Kristina Lend: None declared, Till Uhlig Speakers bureau: Grünenthal, Novartis, Consultant of: Grünenthal, Novartis, Grant/research support from: NORDFORSK, Espen A Haavardsholm Consultant of: Pfizer, AbbVie, Celgene, Novartis, Janssen, Gilead, Eli-Lilly, UCB, Grant/research support from: NORDFORSK, Norwegian Regional Health Authorities, South-Eastern Norway Regional Health Authority, Gerdur Gröndal: None declared, Merete Lund Hetland Consultant of: Abbvie, Biogen, BMS, Celltrion, Eli Lilly, Janssen Biologics B.V, Lundbeck Fonden, MSD, Pfizer, Roche, Samsung Biopies, Sandoz, Novartis, Grant/research support from: Abbvie, Biogen, BMS, Celltrion, Eli Lilly, Janssen Biologics B.V, Lundbeck Fonden, MSD, Pfizer, Roche, Samsung Biopies, Sandoz, Novartis, Marte Heiberg: None declared, Mikkel Østergaard Speakers bureau: Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, Merck, Novartis, Orion, Pfizer, Roche and UCB, Consultant of: Abbvie, BMS, Boehringer-Ingelheim, Celgene, Eli-Lilly, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi and UCB, Grant/research support from: Abbvie, Amgen, BMS, Merck, Celgene and Novartis, Kim Hørslev-Petersen: None declared, Jon Lampa Speakers bureau: Pfizer, Janssen, Novartis, Ronald van Vollenhoven Speakers bureau: Abbvie, Galapagos, GSK, Janssen, Pfizer, R-Pharma, UCB, Consultant of: Abbvie, AstraZeneca, Biogen, BMS, Galapagos, Janssen, Miltenyi, Pifzer, UCB, Grant/research support from: BMS, GSK, UCB, Michael Nurmohamed Speakers bureau: Abbvie, Janssen, Celgene, Consultant of: Abbvie, Grant/research support from: Abbvie, Amgen, Pfizer, Galapagos, BMS.

Pentraxin-3 - a potential biomarker in ANCA-associated vasculitis

OBJECTIVE

The aim of this study was to investigate pentraxin-3 (PTX3) as a potential biomarker of inflammatory activity in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) at baseline and 6 month follow-up in a longitudinal cohort.

METHOD

Plasma PTX3 levels were measured in 79 newly diagnosed or relapsing AAV patients at baseline and 6 month follow-up, and in 23 healthy controls. Urinary PTX3 levels were measured in 34 of the patients. C-reactive protein (CRP), creatinine, and albuminuria were measured and the cumulative glucocorticoid dose at inclusion was calculated. The Birmingham Vasculitis Activity Score (BVAS) was assessed at baseline and follow-up.

RESULTS

Plasma PTX3 levels were significantly higher at baseline than at 6 months (2.85 vs 1.23 ng/mL, p < 0.001). Plasma and urinary PTX3 levels correlated with BVAS at baseline (ρ = 0.45, p < 0.001, and ρ = 0.49, p = 0.008, respectively). A significant correlation between both plasma and urinary PTX3 levels and estimated glomerular filtration rate and albuminuria was found. However, there was no correlation between plasma and urinary PTX3 levels. At baseline, plasma and urinary PTX3 levels were significantly higher in patients with kidney involvement. PTX3 levels did not correlate with CRP, nor was there a correlation between CRP levels and BVAS at baseline.

CONCLUSION

Plasma and urinary PTX3 seem to reflect disease activity in AAV better than the commonly used CRP. PTX3 may have a potential role as a biomarker in monitoring disease activity in AAV patients, particularly in patients with kidney involvement.

POS1230 OUTCOME FOLLOWING COVID-19 INFECTION IN ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)-ASSOCIATED VASCULITIS

Background:

Patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) require immunosuppressive therapy for disease control and reduction of disease relapse and may be at risk for complications during Sars-CoV-2 (COVID-19) infection.

Objectives:

To analyze the consequences of COVID-19 in a large cohort of AAV patients regarding occurrence, need of hospitalization, treatment at the intensive care units (ICU), or death.

Methods:

Data were retrieved from March 2020 to mid-January 2021 from medical records from the AAV cohort (n=233). Patients diagnosed with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) or eosinophilic granulomatosis with polyangiitis (EGPA) were included. Data included age, gender, diagnosis, ongoing immunosuppressive medication at onset of COVID-19 or at last follow-up in non-COVID individuals. Renal involvement (ever) and estimated glomerular filtration rate (eGFR) were included. COVID-19 was confirmed either by a positive PCR test in the upper airways or by serology. Severe COVID-19 was defined as need of non-invasive ventilation, ICU care, and/or death.

Results:

The cohort comprised of 172 patients with GPA, 50 with MPA and 11 with EGPA. There were 121 females (52%). During the study period, 20 patients (8.6%) were diagnosed with COVID-19. The median age at data retrieval in all patients was 68 years (21-93), in the COVID-19 group 63 (29-93) and 68.5 (21-90) years in the non-COVID patients.

Fourty-three patients in all (18%) were hospitalized during the study period of which 11 (4.7%) due to COVID-19 infection. In all, 8 deaths occurred of which 3 were related to COVID-19.

At data retrieval, 110 (47%) patients were on prednisolone treatment, 10/20 (50%) in the COVID-19 group and 100 (47%) in the non-COVID-19 group (p=0.5), with significantly higher doses in COVID-19 patients (p<0.001). In patients hospitalized with COVID-19, 6/11 (54.5%) were on prednisolone, median dose 5 mg/day (0-50). In the total group 112 (48%) were on disease modifying anti-rheumatic drugs (DMARD) and 64 (27.5%) on rituximab as maintenance therapy. Eight patients were on induction treatment with either cyclophosphamide or rituximab.

Of the 20 COVID-19 cases, 8 had severe COVID-19. Of these, 2 were inactive without immunosuppressive treatment, 4 had stable disease with prednisolone (5-7.5 mg/day) in combination with DMARDs, and 2 were active treated with high dose prednisolone (25-50 mg/day) in combination with cyclophosphamide and rituximab (n=1) or rituximab (n=1).

A higher proportion of patients had active AAV (p=0.03) in the severe COVID-19 then in the non-COVID group (10/213 patients).

In the group with the severe COVID-19, 1/8 (12%) patient had rituximab as maintenance therapy, compared to 61/213 (28.6%) in the group of non-COVID-19 patients (p=0.5).

Renal involvement (ever) was present in 144 patients (62%), in 6 patients (30%) with COVID- 19, from which 5 (62%) were in the group of severe COVID-19 patients. Median eGFR did not differ between severe COVID-19 and remaining patients with renal involvement independently of COVID-19 infection.

Conclusion:

We found a high rate of severe COVID-19 infection in our cohort of AAV patients which indicates risk for serious complications, especially in patients with active disease and intense immunosuppressive therapy. Maintenance therapy with rituximab did not seem to increase the risk for severe COVID-19. The findings stress the need for continued shielding and early vaccination in AAV patients.

Disclosure of Interests:

None declared

AB0318 RISK FOR CONCOMITANT AUTOIMMUNITY IN PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME; A SWEDISH COHORT STUDY

Background:

In patients with the antiphospholipid syndrome (APS), concomitant systemic autoimmune rheumatic diseases (SARD) are common and often associated with more disease associated damage.

Less is known about the prevalence of non-rheumatic autoimmune diseases (NRAID) in patients with APS.

Objectives:

To evaluate the incidence and prevalence of concomitant autoimmune diseases (AID) in a cohort of APS patients. The risk of AID was also evaluated with respect to the antiphospholipid antibodies (aPL) profiles.

Methods:

This retrospective cohort study comprises consecutive patients identified with APS through review of electronic medical records at Karolinska University Hospital, Sweden between 2014 and 2020. Exclusion criteria were misdiagnosis and age <18. Descriptive statistics was used for baseline data and multivariable Cox proportional hazard regression analysis to investigate the risk factors to develop new onset AID. Ethical approval was obtained from the Swedish Ethical Review Authority (2020-02333).

Results:

Of 271 included patients, 66% were women and the median age at diagnosis of APS was 43 years (IQR 31–55). At inclusion, 130 (48%) patients presented with other AID; 101 (37%) of them had a concomitant SARD while 54 (19%) had a NRAID. Systemic lupus erythematosus (SLE) was the most frequent in 30% of patients, followed by autoimmune thyroid disease (ATD) in 10% of patients.

In addition, 35 (13%) APS-patients developed AID during the study period, corresponding to an incidence rate of 28.4 (95% CI; 19.3-40.3) per 1.000 person-years with mean time at risk of 4 (±2) years. Twenty-one (8%) patients developed a SARD and further 14 (5%) were diagnosed with a NRAID.

The cumulative incidence for AID was significantly higher in patients with high titers of IgG aPL. Patients that developed SARD had significantly higher median titers of a-β2GPI IgG isotype, p=0.05. In the NRAID group, median a-β2GPI and aCL IgG isotypes were significantly increased, p=0.02 and p=0.04, respectively. The hazard ratio to develop diagnosis of AID was significantly increased in patients with high titers of the IgG isotype aPL (HR 2.4 95% CI; 1.1-5.3). Obstetric APS manifestations were associated with a significantly increased hazard ratio of 2.8 (95% CI; 1.1-7.7) to develop SARD, and also trendwise for AID, as a compound variable.

During the study period, 52 patients had at least one new APS manifestation, as defined by the Sydney criteria (1). In comparison to patients without new manifestations, these patients had significantly higher median titers of aPL of the IgG isotype, and concomitant AID at first visit (p=0.01, p=0.02, respectively).

Conclusion:

APS patients are at high risk to develop other AID, and APS patients with concomitant AID had an increased risk to develop new clinical APS manifestations. These findings might be helpful when considering risk stratification and alternate treatment options in this patient group.

References:

[1]Miyakis S, Lockshin MD, Atsumi T et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006; 4: 295–306.

Acknowledgements:

I have no acknowledgements to declare.

Disclosure of Interests:

None declared

OP0146 TENOSYNOVITIS, SYNOVIAL HYPERTROPHY AND FEET BURSITIS ARE USEFUL ULTRASOUND BIOMARKERS FOR PREDICTING ARTHRITIS DEVELOPMENT IN A POPULATION AT-RISK FOR RHEUMATOID ARTHRITIS

Background:

Musculoskeletal ultrasound (MSUS) evaluation of individuals at risk for developing rheumatoid arthritis (RA) having Anti-Citrullinated Protein Antibody (ACPA) positivity and musculoskeletal complaints, may play an important role in the very early detection of RA.

Objectives:

We aimed to identify which ultrasound markers could predict arthritis development.

Methods:

Individuals with musculoskeletal complaints with a positive anti-CCP2 test were referred to the rheumatology department for a detailed clinical (68 joint count) and MSUS examination of the hands, feet and any symptomatic joints. Only those without clinical and/or MSUS detected arthritis were included in the RISK RA prospective cohort and followed-up over 3 years/ or until arthritis onset. Using EULAR-OMERACT guidelines1, MSUS markers for synovial hypertrophy (SH) and hyperemia (Doppler activity) were documented for each visit. Finger and wrist tendons were screened for any signs of tenosynovitis (TS), and between metatarsal joints for bursitis. Association of MSUS biomarkers with arthritis development was tested (comparing proportions) using Chi-Squared or Fisher’s exact tests.

Results:

288 individuals were included from January 2014 to October 2019 (79% female, 35% RF positive, median age 48 years: IQR: 36-58). Within a median of 38 months (IQR: 1-72) since recruitment, 84 individuals (28%) developed an arthritis diagnosis.

Prior to obtaining any diagnosis (at inclusion and/or follow-up visit), 95 of the 288 individuals (33%) had at least one type of MSUS anatomical modification present (around the tendons, joint synovium and/or within bursal cavities), and 56% (53/95) of these individuals eventually developed arthritis. Of the remaining 193 that did not present with any obvious MSUS changes, 16% progressed towards arthritis development.

The presence of tenosynovitis was detected in 64 of 288 individuals scanned prior to diagnosis and were more frequent in those developing arthritis (44%, 37/84) as compared to those with TS not developing arthritis (13%, 27/204), p<0.0001. The extensor carpi ulnaris wrist tendons were mostly involved. Sonographic changes within the synovium were noted in 11% (32/288) of all individuals, mostly affecting the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints. There was a higher incidence of synovial hypertrophy detected in those developing arthritis (22%, 18/24), as compared to those that remained arthritis free (7%, 14/204), p<0.0001. The MCP joints with synovial hypertrophy were more prone to arthritis development as compared to the MTP’s. Furthermore, we observed a higher frequency of bursitis between the MTP joints in individuals developing arthritis, as compared to individuals having a bursitis who did not develop arthritis (13%, 11/84 versus 7%, 14/204, p=0.009).

Conclusion:

Ultrasound biomarkers such as tenosynovitis of the extensor carpi ulnaris, synovial hypertrophy of the MCP joints and feet bursitis have good potential to predict arthritis development in a population at-risk for rheumatoid arthritis.

References:

[1]Maria-Antonietta D’Agostino et al. RMD Open 2017;3:e 000428

Acknowledgements:

All study participants and patients, including researchers that are part of the multidisciplinary laboratory, clinical and academic teams of the RISK RA study group, as well as all assisting this research in one form or the other are greatly acknowledged.

Disclosure of Interests:

None declared

POS0874 CLOT LYSIS TIME PREDICTS RECURRENT DIGITAL ULCERS IN SYSTEMIC SCLEROSIS AFTER ONE YEAR OF FOLLOW-UP: A NESTED CASE-CONTROL STUDY

Background:

Digital ulcers (DU) are a common visible manifestation of vasculopathy in systemic sclerosis (SSc), which could be recurrent and associated with disability and mortality (1). Although vasculopathy is connected with impaired coagulation/fibrinolysis system and aberrant expression of adhesion molecules, there are few data about their role in developing recurrent DU.

Objectives:

To evaluate the possible role of Fibrin generation/Fibrinolysis parameters and adhesion molecules in the prediction of new ischaemic DU oncet during a 1-year follow-up and their impact on the time to new DU onset (TD).

Methods:

From 58 consecutive patients with SSc who fulfilled the 2013 ACR/EULAR SSc criteria and have never been treated with endothelin receptor antagonist, phosphodiesterase 5 inhibitors or prostanoids, a total of 38 patients with ever had DU, either active at inclusion or in past, were enrolled in a prospective cohort study. Each patient was given a “DU diary”. Demografic, clinical and serologycal data were recorded. The serum concentration of ICAM1 and E selectin were measured by ELISA. Haemostatic potential parameters: overall haemostasis (OHP), overall coagulation (OCP) and overall fibrinolysis (OFP) potential were assessed. Maximum absorbance (Cmax), reflects the fibrin clot density and clot lysis time (Lys50t0, time from initiation of clot formation to the time at which a 50% fall in absorbance from Cmax in the lysis assay), reflects fibrinolytic susceptibility, were calculated (2). Fibrin structure was visualised using scanning electron microscopy (SEM).

Results:

Over the follow-up period,18 patients (45.5%) developed new DU with the average TD of 7.4±2.9 months. There was no differance in ASA and CCB treatment among two groups (p>0.05). The OFP value was significantly decreased (p<0.01), Lys50t0 prolonged (p<0.05), while OHP was increased (p<0.05) in patients experienced new DU. Lys50t0 showed good validity in identifying patients with new DU oncet (AUC 0.683 95% CI 0.5 - 0.9). By multivariate analysis including clinical data in model the Lys50t0 (HR 1.2, 95% CI 1.1-1.3, p=0.018) and active DU at enrollment (HR 9.6, 95% CI 1.4-66.8, p=0.022) were identified as independent risk factors for the occurrence of new DU. TD was inversly correlated with ICAM1(p<0.001), E selectin (p<0.05), Cmax (p <0.05) and Lys50t0 (p<0.001). Model explaining 81.6% of the TD variability included Lys50t0 (β=- 0.55,p=0.003), E selectin (β=- 0.44,p=0.014) and fibrinogen (β=- 0.49,p=0.017). SEM revealed denser fibrin clots with thinner fibres in group experienced new DU compared to clots formed in plasma of patient without DU.

Conclusion:

Our results provide evidence that impaired fibrinolysis has critical role in the progression of microvascular disease, identifing clot lysis time as a strong predictor in the oncet of new digital ulcers in Systemic sclerosis. The higher level of E selectin and the longer lysis time are, the shorter is time until the onset of new digital ulcer. These results could be used in selection of patients at high risk of developing recurrent digital ulcer and therefore allow earlier therapeutic intervention.

References:

[1]Allanore Y, Distler O, Matucci-Cerinic M, Denton CP. Review: Defining a Unified Vascular Phenotype in Systemic Sclerosis. Arthritis Rheumatol. 2018 Feb;70(2):162-170

[2]Carter AM, et al. Heritability of clot formation, morphology, and lysis: the EuroCLOT study. Arterioscler Thromb Vasc Biol. 2007 Dec;27(12):2783-9.

Figure 1.

SEM images of fibrin network in 1 representative sample from a SSc patient with (A) and 1from patient without (B) new DU oncet

Disclosure of Interests:

None declared

Evaluation of risk factors and biomarkers related to arterial and venous thrombotic events in idiopathic inflammatory myopathies

Objectives: This study aimed to assess the contribution of traditional/disease-related risk factors and biomarkers linked to arterial and venous thrombotic events (TEs) in patients with idiopathic inflammatory myopathies (IIMs).Method: The occurrence of arterial and/or venous TEs at the time of or after IIM diagnosis was retrospectively evaluated in a cohort of 253 patients with IIMs, resulting in a final population of 246 IIM patients, 51 with reported TE (cases) and 195 without a history of TE (comparators). Information on disease characteristics and traditional risk factors for arterial and venous TE (essential hypertension, diabetes, dyslipidaemia, smoking, malignancy) was retrieved. Serum levels of anti-phospholipid antibodies (aPLs) and adhesion molecules were analysed at the time of IIM diagnosis and at the time of the TE in cases.Results: One in five IIM patients (21%) had experienced a TE, arterial TE in 22 and venous TE in 29 patients, with a peak prevalence within 5 years after diagnosis. Among traditional/disease-related risk factors, only older age was associated with both arterial and venous TEs, after adjusting for other covariates. Low serum levels of e-selectin were associated with higher odds of developing a TE, without specific association with either arterial or venous TEs. Only 6% of IIM patients had aPLs, with no significant difference between cases and comparators.Conclusions: An increased risk of both venous and arterial TEs should be considered in IIM patients, particularly close to diagnosis and in elderly people. Low serum levels of e-selectin may predict TE in IIM patients, but the underlying biological mechanism is not known.

AB1240 C4B BINDING PROTEIN AND WARFARIN IN THE ANTIPHOSPHOLIPID SYNDROME

Background:

Complement plays a role in the Antiphospholipid Syndrome (APS). C4b Binding Protein (C4BP) is a complement inhibitor with anticoagulant function (1). It belongs to the same protein family as β2GPI, the main antigen in APS. Its main isoform is bound to protein S in the circulation. Levels of both protein S and C4BP are known to be reduced by warfarin treatment (2) as well as by aPL, directly and indirectly.

Objectives:

To investigate the levels of C4BP in primary (p) and secondary (s) APS, also considering warfarin treatment.

Methods:

The total amount of C4BP (C4BPt) was measured by using magnetic carboxylated microspheres which were coupled with a monoclonal antibody against the α-chain of human-C4BP to capture the antigen. To detect C4BPt the same antibody was used, biotinylated. The binding of biotinylated antibodies was detected by streptavidin-phycoerythrin and data were collected using a MAGPIX Multiplex Reader. Using independent t-test, we compared C4BP in 118 SLE patients with repeated positivity for Antiphospholipid antibodies (aPL) (39/118 on warfarin), 291 aPL negative SLE patients (16/291 on warfarin), 67 pAPS (33/67 on warfarin), and 322 controls (none on warfarin). We then performed an interaction and a mediation analysis (3) in the SLE group to study the impact of warfarin on C4BP levels: since warfarin is mostly prescribed to aPL+ patients, it is considered a mediator in the reducing effect of aPL on C4BP. Therefore we compared individuals exposed and non-exposed to the presence of aPL with or without the mediator warfarin and calculated the percentage of reduction in C4BP that could be attributed to aPL or warfarin.

Results:

Overall C4BP is 20% reduced in aPL+ patients (fig 1), independently of SLE, past thrombotic events and nephritis. Warfarin treated patients have lower levels of C4BP (fig 2). According to mediation analysis 11% of C4BP reduction is due to aPL and 9% to warfarin.

Figure 1.

C4BP in different subgroups (67 pAPS, 118 SLEaPL+, 291 SLEaPL-, 322 controls)

Figure 2.

C4BP in 67 pAPS patients, 33/67 on warfarin

Conclusion:

Both aPL and warfarin decrease levels of C4BP, a complement and coagulation regulator. Reduction of this complement inhibitor could contribute to complement activation and thrombosis in APS. Our results raise new questions regarding the effects of warfarin treatment on complement and coagulation in APS.

References:

[1]Dahlbäck B. C4b-binding protein: a forgotten factor in thrombosis and hemostasis. Seminars in thrombosis and hemostasis 2011; 37(4): 355.

[2]Zöller B, García de Frutos P, Dahlbäck B. Evaluation of the relationship between protein S and C4b-binding protein isoforms in hereditary protein S deficiency demonstrating type I and type III deficiencies to be phenotypic variants of the same genetic disease. Blood 1995; 85(12): 3524.

[3]Vanderweele TJ, Vansteelandt S. Conceptual issues concerning mediation, interventions and composition. Statistics and Its Interface 2009; 2(4): 457-68.

Disclaimer:

AV is employed at the Swedish Medical Products Agency, the views expressed in this paper are the personal views of the authors and not necessarily the views of the Governement Agency

Acknowledgments:

Thanks to the Biostatistics Core Facility, Karolinska University

Disclosure of Interests:

None declared

FRI0232 ALTERED FIBRIN CLOT PROPERTIES IN PATIENTS WITH SYSTEMIC SCLEROSIS

Background:

Vasculopathy in Systemic sclerosis (SSc) is connected with the activation of coagulation. However, the fibrinolytic activity still remains unclear since the most preliminary evidences are discordant (1, 2).

Objectives:

To assess the haemostatic function, fibrin clot density and clot lysis time in SSc patients and healthy controls (HC) to determine their relation to disease findings.

Methods:

Patients who fulfilled the 2013 ACR/EULAR SSc criteria and have never been treated with endothelin receptor antagonist, phosphodiesterase 5 inhibitors or prostanoids were eligibile. Our study included 58 SSc patients [36 limited (lcSSc) and 22 diffuse cutaneous SSc (dcSSc)] and 46 sex/age-matched HC. Clinical evaluation of patients was performed, including high-resolution CT (HRCT), pulmonary function tests and the revised EUSTAR activity index. The interstitial lung disease (ILD) group (n = 15) was defined as moderate or severe changes on HRCT, with a forced vital capacity (FVC) < 85% predicted, without evidence of significant pulmonary arterial hypertension. The serum concentration of ICAM1 and von Willebrand factor antigen (VWF) were measured by ELISA. Haemostatic potential parameters; including overall haemostasis (OHP), overall coagulation (OCP) and overall fibrinolysis (OFP) potential, were assessed and endogenous thrombin potential (ETP) was determined. Maximum absorbance (Cmax), reflects the fibrin clot density and clot lysis time (Lys50t0), reflects fibrinolytic susceptibility, were calculated from OHP and OCP curves (3). Fibrin structure was visualised using scanning electron microscopy (SEM).

Results:

The OFP value was significantly decreased, Lys50t0 prolonged (p<0.05), while OHP and ETP were increased (p<0.05) in patients. In dSSc group ETP, OHP, Cmax and Lys50t0 were higher compared to HC (p<0.05). In SSc group, a positive association was found between coagulation parameters (OCP, OHP, Cmax) and the erythrocyte sedimentation rate (ESR), fibrinogen and ICAM1 (respectively p<0.05). Lys50t0 was positively correlated with ICAM1, ESR and VWF (respectively p<0.001, p<0.05, p<0.05). An inverse correlation was found between Cmax and both the diffusing capacity of the lungs for carbon monoxide (r=-0.408, p<0.01) and FVC (r=-0.318, p<0.01). Increased Cmax was found in ILD respect to HC (p<0.01). Denser plasma clot was associated with active disease (p<0.01). Longer Lys50t0 was observed in pitting scars group (p<0.01). Prolonged Lys50t0 was independently predicted by ICAM1 (OR 1.12, 95% CI 1.03–1.2, p<0.01).

Conclusion:

Our results provide evidences of denser plasma fibrin clot among patients with lung involvement and impaired fibrinolysis, selectively presented among SSc patients with piting scars. Thus, these patients might be at risk for thrombotic complications. Raised ICAM-1 levels could reflect impaired fibrinolysis, giving insight the important role of this molecule in endothelial homeostasis.

References:

[1]Cerinic MM, et al. Blood coagulation, fibrinolysis, and markers of endothelial dysfunction in systemic sclerosis. Semin Arthritis Rheum. 2003;32:285–95

[2]Lippi G, et al. Plasma D-dimer concentration in patients with systemic sclerosis.Thromb J. 2006;4:2.

[3]Carter AM, et al. Heritability of clot formation, morphology, and lysis: the EuroCLOT study. Arterioscler Thromb Vasc Biol. 2007 Dec;27(12):2783-9

Figure 1.

SEM images of fibrin network in 1 representative sample from a SSc (A) and 1from HC sample (B).

Disclosure of Interests:

Jelena Colic: None declared, Aleksandra Antovic: None declared, Iva Pruner: None declared, Jelena Vojinovic Consultant of: Roche, Abbvie, Pfizer, MSD, Speakers bureau: Roche, Abbvie, Pfizer, MSD, Mirjana Sefik Bukilica: None declared, Nemanja Damjanov Grant/research support from: from AbbVie, Pfizer, and Roche, Consultant of: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche, Speakers bureau: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche

SAT0584 SPECIFIC ACPA REACTIVITIES AND INFLAMMATORY BIOMARKERS ALONG WITH ULTRASOUND TENOSYNOVITIS ARE ASSOCIATED WITH ARTHRITIS ONSET IN A POPULATION AT RISK FOR RHEUMATOID ARTHRITIS

Background:

Anti-citrullinated protein antibodies (ACPA) are characteristic markers for rheumatoid arthritis (RA), developing years before disease onset. Early clinical and biological biomarkers could provide useful information on the onset of RA in predisposed individuals.

Objectives:

The aim of the study was to investigate whether ACPA along with inflammatory markers and musculoskeletal ultrasound changes could predict arthritis development in individuals at risk for RA.

Methods:

ACPA-positive individuals with musculoskeletal complaints were referred from primary care to a rheumatology clinic, recruited in the Risk-RA research program and followed-up for up to 3 years, between April 2014 and October 2019. All individuals lacked arthritis both at clinical examination by a trained rheumatologist and ultrasound assessment of hands and feet and any other symptomatic joints (according to EULAR-OMERACT definition). Blood samples were collected at inclusion and were analyzed for 15 ACPA fine specificities (by custom made peptide array), 92 inflammation-associated protein biomarkers (by multiplex immunoassay with Olink extension technology) and HLA-SE (DR low resolution kit). Statistical analysis used univariate and multivariate models with backwards selection and cox regression.

Results:

268 individuals with a median age of 48 (36-58) were recruited, out of which 212 (79%) were females. 75 (28%) developed arthritis within 11 months of follow-up while the median follow-up for those not developing arthritis was 21 months (14-28). Increased ACPA levels, shorter symptom duration and RF positivity were the main differences between individuals developing arthritis and those who did not. In univariate models, the presence of HLA-SE, specific ACPA reactivities, certain inflammatory markers and ultrasound-detected tenosynovitis were associated with arthritis development. In multivariate analysis the presence of anti-cit-fillagrin (HR 2.1 (95% CI 1.2-3.7, p 0.01), IL6 levels (HR 1.4 (95% CI 1.2-1.7, p 0.0001) and tenosynovitis (HR 2.9 (95% CI 1.7-5.0, p 0.0001) remained significant predictors for arthritis onset.

Conclusion:

Certain ACPA reactivities together with inflammatory markers and ultrasound-detected tenosynovitis predict arthritis development in predisposed individuals for developing RA.

Disclosure of Interests:

None declared

The antiphospholipid syndrome - often overlooked cause of vascular occlusions?

The antiphospholipid syndrome (APS) was fully recognized as a clinical entity in the early 1980s. Still, more than 30 years later, the epidemiology of APS is not well described, and furthermore, APS remains a challenge in terms of both diagnostic issues and clinical praxis involving a wide range of specialties. To date, there are no diagnostic criteria for APS. The present classification criteria rely on a combination of clinical manifestations and persistently positive tests for antiphospholipid antibodies (aPL). Clinical symptoms comprise vascular thrombosis, which can affect any vascular bed, including venous, microvascular and arterial vessels, and a set of pregnancy morbidities including early and late miscarriages, foetal death and preeclampsia. APS is more frequent among patients with other autoimmune diseases, and it is especially common in systemic lupus erythematosus (SLE). Importantly, APS symptoms can present in almost any medical specialty, but general knowledge and most previous clinical studies have essentially been confined to haematology, rheumatology and obstetrics/gynaecology. However, recent data demonstrate a relatively high prevalence of aPL also in patients from the general population who suffer from vascular occlusions or pregnancy complications. It is important that these patients are recognized by the general health care since APS is a treatable condition. This review aims to summarize the present knowledge on the history, pathogenesis, clinical manifestations and treatment of APS in order to urge a wide range of clinicians to consider comprehensive assessment of all patients where the diagnosis APS may be conceivable.

Obstetric outcomes in patients with primary thrombotic and obstetric antiphospholipid syndrome and its relation to the antiphospholipid antibody profile

Introduction: Previous studies suggested different obstetric outcomes between patients with thrombotic or obstetric antiphospholipid syndrome, but the data are inconclusive. Aims: To investigate obstetric outcomes and their relation to the antiphospholipid antibody profile in primary thrombotic or obstetric antiphospholipid syndrome patients and compare those to a control population. Materials and methods: A retrospective single-centre study on a cohort of 30 pregnant women with primary antiphospholipid syndrome treated at Karolinska University Hospital Solna, Sweden between 2000 and 2016. The pregnancy outcomes were compared to the outcomes of all pregnancies in Stockholm County during the same period. Results: Preeclampsia ( p < 0.001), low birth weight at delivery ( p = 0.001), Apgar < 7 at 5 minutes ( p < 0.001) and small infants ( p < 0.001) were more common in antiphospholipid syndrome patients compared to controls. Obstetric antiphospholipid syndrome patients had a higher incidence of small infants ( p = 0.023), lower birth weight ( p = 0.013) and infants born with complications ( p=0.004) compared to thrombotic antiphospholipid syndrome. Mothers with triple antibody positivity had a higher incidence of preeclampsia ( p = 0.03), preterm delivery ( p = 0.011), small infants ( p=0.002) and infants born with complications ( p = 0.012). Conclusions: Patients with primary antiphospholipid syndrome, especially those with obstetric antiphospholipid syndrome and triple antibody positivity, are at higher risk for adverse pregnancy outcomes, even under antithrombotic treatment. More frequent antenatal controls in high-risk patients can further improve outcomes.

Does Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Contribute to Impairment of Fibrinolysis in Patients with Preeclampsia and/or Intrauterine Fetal Growth Retardation?

Thrombin Activatable Fibrinolysis Inhibitor (TAFI) is a relatively recently described glycoprotein (MM 55 KDa) that can be converted into its active form by the thrombin/thrombomodulin complex and potentially inhibits fibrinolysis. Since it represents a link between coagulation and fibrinolysis, TAFI can be expected to play a part in various clinical conditions associated with a thrombotic tendency. Preeclampsia (PE) and intrauterine fetal growth retardation (IUFGR) are fairly common complications of pregnancy that are characterized by hemostatic abnormalities. TAFI antigen and its influence on hemostasis was investigated in 46 women with PE and/or IUFGR and in 16 normal pregnancies. We found a significant decrease of TAFI antigen in the patient group. Using the recently described method Overall Hemostatic Potential (OHP) in plasma, we measured clot lysis time (CLT) and overall fibrinolytic potential (OFP). We found that CLT is prolonged and OFP decreased in patients with PE and/or IUFGR. Since OFP did not increase after addition of the specific inhibitor of TAFI (potato tuber carboxypeptidase inhibitor), it seems that TAFI does not contribute to the impairment of fibrinolysis in these patients. Since serum albumin was decreased together with presence of proteinuria and aminotransferases were increased in the patients, it seems that one explanation for the decrease in TAFI could be reduced hepatic synthesis and an increased loss in urine. It can be speculated that this mechanism can prevent more serious thrombotic complications in patients with PE and/or IUFGR.

Is a decrease of microparticles related to improvement of hemostasis after FVIII injection in hemophilia A patients treated on demand?

BACKGROUND

Microparticles (MPs) are small membrane vesicles (0.1-1 μm) released from various cells after activation and/or apoptosis. There are limited data about their role in hemophilia A.

PATIENTS AND METHODS

Blood samples were taken before and 30 min after FVIII injection in 18 patients with severe hemophilia A treated on demand. Flow-cytometric determination of total MPs (TMPs) using lactadherin, platelet MPs (PMPs) (CD42a), endothelial MPs (EMPs) (CD144) and leukocyte MPs (LMPs) (CD45) was performed. The results were compared with data on endogenous thrombin potential (ETP), overall hemostatic potential (OHP), fibrin gel permeability and thrombin-activatable fibrinolysis inhibitor (TAFI).

RESULTS AND CONCLUSIONS

TMPs and PMPs decreased after treatment (to 1015 ± 221 [SEM] and 602 ± 134 × 10(6)  L(-1) ) in comparison with values before treatment (2373 ± 618 and 1316 ± 331; P < 0.01). EMPs also decreased after treatment (78 ± 12 vs. 107 ± 13; P < 0.05) while LMPs were not influenced. Both TMP and PMP counts were inversely correlated, moderately but statistically significantly, with data on OHP, ETP, fibrin network permeability and TAFI/TAFIi (P < 0.05 for all). EMP counts were correlated only with ETP (P < 0.05), while LMP counts did not show any correlation. TMP and PMP counts were also inversely correlated with FVIII levels (P < 0.05). TMP, PMP and EMP counts decreased after on-demand treatment with FVIII concentrate in hemophilia A patients. The decrease in circulating MPs, which were inversely correlated with hemostatic activation, may imply that MPs are incorporated in the hemostatic plug formed after FVIII substitution at the site of injury.

Studies of microparticles in patients with the antiphospholipid syndrome (APS)

OBJECTIVES

To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls.

MATERIAL AND METHOD

Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized < 1.0 µm, negative to phalloidin, positive to lactadherin and positive to either CD42a (PMPs), CD144 (EMPs) or CD14 (MMPs). Exposure of CD142 (TF) was measured on CD144 positive MPs.

RESULTS

Total number of MPs (i.e. lactadherin positive particles) was higher in APS patients versus controls (p < 0.001). An increased number of EMPs (p < 0.001), increased TF-positive EMPs (p < 0.001) and increased MMPs (p < 0.001) were also observed. PMP numbers did not differ between the groups. None of the MP types differed in numbers between obstetric and thrombotic APS patients.

CONCLUSION

We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.

Increased hemostasis potential persists in women with previous thromboembolism with or without APC resistance

BACKGROUND

Activated thrombin generation and depressed fibrinolysis due to the presence of activated protein C (APC) resistance with or without factor (F)V Leiden mutation are associated with development of deep venous thrombosis (DVT).

OBJECTIVE

A better understanding of the mechanism behind the risk of recurrence of DVT, using our new, recently developed assay of overall hemostasis potential (OHP).

PATIENTS AND METHODS

Levels of OHP, as well as APC resistance and FV Leiden mutation, were determined in 88 women (cases) who had previously experienced DVT in connection with pregnancy, and in 25 young healthy individuals (controls). Clotting time and clot lysis time were also investigated.

RESULTS

OHP levels in the patients were increased compared with the controls. In the cases with APC resistance and the Leiden mutation this imbalance in hemostasis potential was more severe than in those without. The group with the more severe imbalance had shorter clotting times and longer clot lysis times.

CONCLUSIONS

A procoagulant state perseveres in patients with a history of pregnancy-related DVT, even after the symptomatic phase is over. The mechanisms behind such an imbalance in overall hemostasis are enhanced thrombin generation and depressed fibrinolysis. These findings may underscore the need for thromboprophylaxis to prevent recurrence of thromboembolism in risk situations.

Overall haemostatic potential can be used for estimation of thrombin-activatable fibrinolysis inhibitor-dependent fibrinolysis in vivo and for possible follow-up of recombinant factor VIIa treatment in patients with inhibitors to factor VIII

Thrombin generation induced by recombinant factor VIIa (rFVIIa) in patients with haemophilia and/or inhibitors to factor VIII/IX could enhance generation of thrombin-activatable fibrinolysis inhibitor (TAFI), a recently described link between coagulation and fibrinolysis. TAFI is unstable and it is not easy to measure its active form in vivo. Overall haemostatic potential (OHP) is a novel method for haemostasis estimation, based on determination of the fibrin aggregation curve in which tiny amounts of thrombin are used for activation of clotting. We measured OHP in six patients with inhibitors to factor VIII before injection of rFVIIa and 10 and 120 min thereafter. Overall fibrinolytic potential (OFP) and clot lysis time (CLT) analysed by this method could be used for indirect estimation of TAFI generation. We found no change in pro-TAFI and total TAFI antigen before and after treatment with rFVIIa. OHP was almost undetectable before treatment but increased into the range of normal pooled plasma 10 and 120 min after rFVIIa treatment, as did CLT. However, after addition of potato tuber carboxypeptidase inhibitor, a specific inhibitor of TAFI, the shortening of CLT was lower than that in NPP. OFP was increased in patient plasma both 10 and 120 min after treatment compared with NPP. There was a strong positive correlation between pro-TAFI concentration and shortening of CLT after PTCI addition and a negative correlation between pro-TAFI concentration and OFP 10 min after rFVIIa injection. Thus, rFVIIa normalizes OHP and CLT 10 min after injection. While this improvement slightly decreases, but still exists after 2 hours, it suggests efficacy in bleeding prevention using a protocol based on rFVIIa administration every 2 hours.

Does thrombin activatable fibrinolysis inhibitor (TAFI) contribute to impairment of fibrinolysis in patients with preeclampsia and/or intrauterine fetal growth retardation?

Thrombin Activatable Fibrinolysis Inhibitor (TAFI) is a relatively recently described glycoprotein (MM 55 KDa) that can be converted into its active form by the thrombin/thrombomodulin complex and potentially inhibits fibrinolysis. Since it represents a link between coagulation and fibrinolysis, TAFI can be expected to play a part in various clinical conditions associated with a thrombotic tendency. Preeclampsia (PE) and intrauterine fetal growth retardation (IUFGR) are fairly common complications of pregnancy that are characterized by hemostatic abnormalities. TAFI antigen and its influence on hemostasis was investigated in 46 women with PE and/or IUFGR and in 16 normal pregnancies. We found a significant decrease of TAFI antigen in the patient group. Using the recently described method Overall Hemostatic Potential (OHP) in plasma we measured clot lysis time (CLT) and overall fibrinolytic potential (OFP). We found that CLT is prolonged and OFP decreased in patients with PE and/or IUFGR. Since OFP did not increase after addition of the specific inhibitor of TAFI (potato tuber carboxypeptidase inhibitor), it seems that TAFI does not contribute to the impairment of fibrinolysis in these patients. Since serum albumin was decreased together with presence of proteinuria and aminotransferases were increased in the patients, it seems that one explanation for the decrease in TAFI could be reduced hepatic synthesis and an increased loss in urine. It an be speculated that this mechanism can prevent more serious thrombotic complications in patients with PE and/or IUFGR.

The assay of overall haemostasis potential used to monitor the low molecular mass (weight) heparin, dalteparin, treatment in pregnant women with previous thromboembolism

The present study aimed to assess whether the determination of overall haemostasis potential (OHP) in plasma is powerful enough to monitor the prophylactic effect of low molecular mass heparin (dalteparin, Fragmin) in patients with increased risk of thromboembolitic events. In five pregnant women who had a history of deep venous thrombosis, OHPs were kinetically investigated in gestation weeks 32-35 twice during 24 h (before injection and after 1, 2, 4, 6, 8, 10, 12, 14, 16 and 24 h). Levels of anti-activated factor X (anti-FXa), reflecting dalteparin activity, as well as prothrombin fragments 1 + 2 (F1 + 2) and soluble fibrin, were also measured. In converse relation to changes of anti-FXa, OHPs decreased reaching the lowest level between 2 and 8 h after the injection, and then rose again, returning to the levels around those before the administration. There were no significant variations in concentrations of F1 + 2 and soluble fibrin during the observation course. These findings indicate that the OHP assay can monitor the alteration of haemostatic balance under the dalteparin influence while anti-FXa only shows the activity of the drug present in plasma. Additionally, analyses of thrombin generation markers are not useful to screen immediate changes in the haemostatic system after dalteparin injection.

A simple and rapid laboratory method for determination of haemostasis potential in plasma. II. Modifications for use in routine laboratories and research work

To offer a suitable method for use in routine laboratories and research work, some modifications were made in the assay of overall haemostatsis potential (OHP) we developed earlier. Thrombin in a decreased dose with or without tissue-type plasminogen activator was added to plasma for initiation of fibrinogen clotting. Areas under two fibrin-aggregation curves i.e., above-mentioned OHP and overall coagulation potential (OCP) were thus created. A difference between the two parameters reflects the overall fibrinolysis potential (OFP), calculated by ((OCP-OHP)/OCP) x 100%. To obtain reference ranges, investigations were performed in 142 healthy adults of different ages and in 29 healthy women with a normal pregnancy. In 16 patients suffering from coronary heart disease (CHD), OCPs and OHPs increased but OFPs decreased. In 10 pre-eclamptic women with moderate enhancement of OCP, the OHPs became noticeably higher in most while the OFPs lower. Extremely low or undetectable levels of OHP and OCP were shown in samples of Factors VIII-, IX-, VII-, V-, X- or II-deficient plasma. In 13 healthy volunteers treated with acetylsalicylic acid (ASA), OHPs expectedly declined during the administration and rose again after withdrawal. The above findings demonstrate that the modifications in the present study have rendered the method more effective for detecting haemostatic changes and relevant for monitoring treatments.