Introduction
Recent studies have noted an increased incidence of venous thromboembolisms (VTEs) during active flares of ANCA-associated vasculitis (AAV) (1). A landmark analysis of 33 autoimmune disorders in a Swedish cohort found a standardized incidence rate of 6.57 within the first year of diagnosis in patients with granulomatosis with polyangiitis (GPA) (2). The Wegener’s Clinical Occurrence of Thrombosis (WECLOT) study showed an incidence rate of 7.0 for first VTE per 100 person-years, whereas a healthy, demographically matched Swedish population had a VTE incidence rate of 0.31 per 100 person-years (3). In patients without active vasculitis, there is evidence of hypercoagulability with increased thrombin formation (4) and risk of VTE remains elevated (1).
A large retrospective cohort study of AAV subtypes found VTE incidences of 8.2% among patients with eosinophilic GPA, 8% among patients with GPA, and 7.6% among patients with microscopic polyangiitis (MPA) (5). A recent study of trial data from the European Vasculitis Study Group found C-reactive protein (CRP), cutaneous involvement, gastrointestinal involvement, and worsening renal function to be associated with increased risk of VTE among patients with GPA and MPA (6). Patients with AAV also have a greater risk of cardiovascular events, such as acute coronary syndrome, new onset angina, peripheral vascular disease, and transient ischemic attacks, which can be seen in patients with prothrombotic states (7).
The pathophysiology of thrombotic events in AAV is not well understood. Several studies have sought to uncover molecular determinants of active vasculitis. There is increased recognition that antibodies against proteinase-3 (PR3) correlates well with the incidence of VTE (6,8). A slightly older study, however, did note a protective effect of PR3-ANCA (1). More recent studies have identified plasminogen as a potential target antigen in patients with PR3 vasculitis and demonstrated its interaction with autoantibodies directed toward complementary PR3, leading to decreased plasmin levels and fibrinolysis with a subsequent hypercoagulable state (9,10). Additionally, it is increasingly appreciated that neutrophil α-defensins—antimicrobial particles released from activated neutrophils—and neutrophilic-endothelial interactions play a significant role in thrombosis among patients with AAV (11,12). In this study, we aimed to determine the incidence of VTE in a well characterized, single center cohort and uncover new factors that may be associated with increased risk of thrombosis.
Materials and Methods
Patients
Our cohort was derived from patients enrolled in an institutional review board–approved database at the Johns Hopkins Vasculitis Center. Patients with a diagnosis of AAV between 1998 and 2018 were included in this study. They were classified as GPA, MPA, or eosinophilic GPA, based on the 2012 Chapel Hill Consensus Nomenclature (13). Patients were further stratified by ANCA type. Information related to patient demographics, serum albumin, CRP, renal function, proteinuria assessed on a spot urine sample, comorbidities, newly diagnosed/relapsing disease, specific organ involvement, and details of remission induction therapy and concomitant medications were obtained by review of electronic medical records. Disease activity at diagnosis and at the time of VTE was quantified retrospectively with the Birmingham Vasculitis Activity Score version 3 (BVAS 3) (14). Damage was quantified with the Vasculitis Damage Index (VDI) (15). GFR was estimated using the CKD Epidemiology Collaboration formula (16). Obesity was defined as body mass index (BMI) >30 kg/m2. Rapidly progressive GN (RPGN) was defined as at least a 20% decrease in eGFR over a 2-week period along with hematuria and proteinuria. VTE was defined as the presence of either deep venous thrombosis (DVT), pulmonary embolism (PE), or both.
Statistical Analysis
Baseline characteristics of patients are displayed as mean±SD or quantity (%) for continuous and categoric variables, respectively. Characteristics between patients with and without VTE were assessed with the Wilcoxon rank sum test for continuous and the chi-squared test for categoric data. To elucidate factors associated with VTE, univariate logistic regression models were performed with P<0.05 considered significant. For every significant parameter in univariate analyses, multivariate logistic models were constructed, adjusting for age, gender, and weight. The strength of each variable’s association with VTE is presented as an odds ratio (OR) with 95% confidence intervals (95% CIs) and P values. All statistical analyses were performed with RStudio version 1.2.5001 (RStudio, Inc., Boston, MA).
Results
Patient Characteristics
This retrospective cohort study included 162 patients with AAV. We stratified all analyses by VTE and non-VTE subgroups (see Table 1). A total of 22 subjects (14%) had recorded VTEs, 13 of which were DVTs, four PEs, and five had both. Of the 22 patients, 20 experienced VTE during active disease whereas the remaining two were in disease remission at the time of VTE. There was no preceding history of trauma or surgery in patients who developed VTE. There was no prior history of DVT or PE in the VTE group. The median time to VTE was 1 month (range 1–239 months). Overall, a significantly higher BVAS at diagnosis was seen in patients with VTE: 19 (5–24) versus 14 (2–28), P=0.01. Of the 86 patients who were PR3-ANCA positive, 18 were found to have VTE, whereas four of 71 who were positive for myeloperoxidase (MPO)-ANCA had VTE (P=0.01). Looking at classic comorbidities and risk factors for VTE, there were significant differences in weight (96.3 kg versus 81.3 kg, P=0.005) and BMI (P<0.001) between the two groups. Notably, there were no significant differences between other characteristics, including gender, age, smoking status (never, prior, current), eGFR, nephrotic range protienuria, hypertension, statin use, anticoagulation/antiplatelet therapy, use of rituximab or cyclophosphamide for induction therapy, or presence of alveolar hemorrhage.
Table 1. -
Demographics and baseline characteristics of patients with ANCA-associated vasculitis
| Characteristic |
VTE |
No VTE |
P Value |
| Subjects |
22 |
140 |
|
| Age of onset, yr |
54.2±19.7 |
55.1±16.9 |
0.99 |
| Female sex |
14 (64) |
84 (60) |
0.93 |
| Length of follow-up, mo |
57.3±72.2 |
72.9±61.6 |
0.04
a
|
|
Diagnosis
|
|
|
0.68 |
| GPA |
16 (73) |
89 (64) |
|
| MPA |
6 (27) |
50 (36) |
|
|
ANCA associations
|
|
|
0.01
a
|
| PR3-ANCA |
18 (82) |
68 (49) |
|
| MPO-ANCA |
4 (18) |
67 (48) |
|
| None |
0 (0) |
5 (4) |
|
|
Smoking status
|
|
|
0.41 |
| Never |
13 (59) |
94 (67) |
|
| Prior |
9 (41) |
41 (29) |
|
| Current |
0 |
5 (4) |
|
| Weight, kg |
96.3±22.9 |
81.3±20.8 |
0.005
a
|
| Height, m |
1.68±0.14 |
1.68±0.11 |
0.56 |
| BMI, kg/m2
|
33.3±5.7 |
28.3±6.1 |
<0.001
a
|
| Obesity (BMI ≥30 kg/m2) |
15 (68) |
48 (34) |
0.01
a
|
| Baseline creatinine, µmol/ml, mean (SD) |
3.0±1.9 |
3.0±2.9 |
0.29 |
| Baseline GFR, ml/min, mean (SD) |
35.7±29.6 |
46.3±38.8 |
0.48 |
| Alveolar hemorrhage, n (%) |
5 (23) |
11 (8) |
0.08 |
| Rapidly progressive GN, n (%) |
12 (55) |
36 (26) |
0.01
a
|
| Treated hypertension, n (%) |
13 (59) |
77 (55) |
0.89 |
| Statin treatment, n (%) |
8 (36) |
47 (34) |
0.98 |
| C-reactive protein (0–0.5 mg/L), mean (SD) |
14.0±21.8 |
9.4±23.2 |
0.14 |
| Proteinuria (grams/d), mean (SD), mean (SD) |
2.95±0.66 (20) |
3.69±0.70 (115) |
<0.001
a
|
| Hypoalbuminemia (<3.0 g/dl), n (%) |
12 (55) |
24 (17) |
<0.001
a
|
| Proteinuria (>3500 mg), n (%) |
0/20 |
14/115 (12) |
0.21 |
| Rituximab induction, n (%) |
17 (77) |
83 (59) |
0.16 |
| Cyclophosphamide induction, n (%) |
8 (36) |
66 (47) |
0.48 |
| History of malignancy, n (%) |
0 |
6 (4) |
0.61 |
|
Use of aspirin/clopidogrel/warfarin
|
|
|
0.59 |
| Aspirin |
4 (18) |
18 (13) |
|
| Clopidogrel |
0 |
0 |
|
| Warfarin |
0 |
4 (3) |
|
| BVAS at diagnosis, median (range) |
19 (5–26) |
14 (2–28) |
0.01
a
|
VTE, venous thromboembolism; GPA, granulomatosis with polyangiitis; MPA, microscopic polyangiitis; PR3, proteinase-3; MPO, myeloperoxidase; BMI, body mass index; BVAS, Birmingham Vasculitis Activity Score.
aStatistically significant (P<0.05).
Logistic Regressions
Univariate logistic regressions were performed to identify variables that might be significantly associated with the development of VTEs. Classic risk factors such as BMI (OR, 1.1; 95% CI, 1.0 to 1.2; P=0.002) and the presence of obesity (OR, 3.3; 95% CI, 1.3 to 9.4; P=0.02) significantly increased risk of VTE (Supplemental Table 1). The presence of RPGN also significantly increased risk of VTE (OR, 3.47; 95% CI, 1.38 to 8.89; P=0.008). Hypoalbuminemia (<3.0 g/dl) also increased VTE risk (OR, 5.70; 95% CI, 2.22 to 15.03; P<0.001). BVAS scores were separated into low (<8), medium (<16), high (<24), and extreme (≥24) categories. For each subsequent level of activity, the odds of developing VTE increased significantly (OR, 1.82; 95% CI, 1.06 to 3.30; P=0.04). Higher BVAS cutaneous (OR, 3.32; 95% CI, 1.19 to 8.92; P=0.02) and BVAS chest (OR, 4.01; 95% CI, 1.41 to 14.43; P=0.02) scores were also associated with VTE, whereas other BVAS and VDI subtypes were not. There was also no evidence of a relationship between the development of VTE and age, gender, CRP, or presence of alveolar hemorrhage. Additional BVAS and VDI analyses are included in Supplemental Tables 1 and 2.
A multivariate regression model was constructed and used to confirm associations demonstrated by univariate analyses (Table 2). The presence of PR3-ANCA versus MPO-ANCA increased the odds of developing VTE significantly (OR, 4.77; 95% CI, 1.32 to 20.77; P=0.02). Hypoalbuminemia (OR, 5.84; 95% CI, 1.78 to 20.69; P=0.004) and the classic risk factor of BMI (OR, 1.16; 95% CI, 1.05 to 1.27; P=0.002) were both significant factors in the development of VTE in the data set. BVAS activity level, RPGN, age of onset, and gender were not determined to be significant.
Table 2. -
Multivariate logistic regression
| Characteristic |
Odds Ratio (95% CI) |
P Value |
| Age of onset, yr |
1.02 (0.99 to 1.07) |
0.21 |
| Female sex |
1.12 (0.36 to 3.61) |
0.85 |
| BMI, kg/m2
|
1.18 (1.08 to 1.31) |
<0.001
a
|
| PR3-ANCA |
4.77 (1.32 to 20.77) |
0.02
a
|
| Hypoalbuminemia |
5.84 (1.78 to 20.69) |
0.004
a
|
| RPGN |
2.60 (0.80 to 8.72) |
0.11 |
| BVAS level (low, medium, high, extreme) |
1.17 (0.57 to 2.44) |
0.68 |
BMI, body mass index; PR3, proteinase-3; RPGN, rapidly progressive GN; BVAS, Birmingham Vasculitis Activity Score.
aStatistically significant (P<0.05).
Discussion
Thrombosis is recognized as a significant consequence of AAV, particularly during active disease. Although classic risk factors for VTE were identified in our study, several disease-specific variables persisted throughout analyses. Gender and age were not significantly associated in our multivariate analyses, confirming a previous study (6). Notably, episodes of VTE occurred within 1 month of diagnosis in our data set, demonstrating the role of disease activity in determining VTE risks (1). These findings are consistent with prior studies, specifically the WECLOT trial which found VTE occurred a median of 2.1 months after active disease (3). In our study, VTEs occurred in 14% of patients with AAV. Importantly, we were able to confirm the association of PR3-ANCA and hypoalbuminemia with VTE incidence in our data set (6,17). We were unable to confirm a previously seen association between alveolar hemorrhage and VTE in our data set, likely due to the limited number of patients with alveolar hemorrhage in our data set (8).
Our study confirms a strong relationship between PR3-ANCA and VTE risk, as seen in prior studies (6,8). In contrast, VTE incidence was higher in patients with MPO-ANCA in a retrospective study by Stassen et al. (1) The reason for this discrepancy is unclear. These observations, therefore, further support a pathogenic role for anti-plasminogen antibodies, previously observed in patients with PR3-ANCA, and their interactions with a highly restricted motif on plasminogen resulting in decreased conversion of plasminogen to plasmin and a subsequent increase in thrombotic potential (9,10,17). These results further highlight the role of endothelial damage, likely propagated by neutrophil-endothelial interactions in a proinflammatory state in patients with AAV (11,12).
High BMI was associated with a higher risk of VTE. High BMI, being a risk factor for metabolic syndrome, induces a proinflammatory state in AAV, promoting a procoagulant state and increased VTE risk (18). We were able to confirm a relationship between disease activity, specifically hypoalbuminemia, and risk of VTE (17). Albumin has antithrombotic effects and contributes to increased VTE risk (19). In addition, in the setting of hypoalbuminemia, there is increased hepatic production of factors V and VIII and fibrinogen as a compensatory mechanism. We were unable to confirm an association between CRP levels and VTE (6). We were also unable to confirm whether increasing activity levels at diagnosis, identified by higher BVAS activity levels (low, medium, high, extreme), resulted in more VTEs.
There are several limitations to this study. First, the median time to VTE is assessed from the time of diagnosis rather than the date of disease onset, which may not be the same. Measurements for other known predisposing factors for VTE like factor VIII level, protein S, antithrombin III, factor V Leiden, and markers of endothelial function were not performed in this study Additionally, VTEs were diagnosed clinically and not through routine screening, and the cohort did not undergo intermittent prophylactic screening.
Overall, this study found a significant association between PR3-ANCA and hypoalbuminemia with the incidence of VTE. BMI persisted in our multivariate models as a significant risk factor for VTE. We were unable to confirm previously observed relationships such as alveolar hemorrhage with VTE. Developing a metric or biomarker of PR3-plasminogen interactions, the extent of neutrophilic-endothelial damage, and neutrophil α-defensins in AAV may offer clinicians the potential to stratify patients and determine need for prophylactic anticoagulation.
Disclosures
E. Gapud is a Jerome L. Greene Foundation Scholar. D. Geetha reports acting as consultant to Aurinia and ChemoCentryx. B. Antiochos, B. Isaacs, and P. Seo have nothing to disclose.
Funding
This research was funded by the Johns Hopkins University Rheumatology Cupid Discovery Fund.
Supplemental Material
This article contains the following supplemental material online at http://kidney360.asnjournals.org/lookup/suppl/doi:10.34067/KID.0000572019/-/DCSupplemental.
Supplemental Table 1. Univariate logistic regression (response: VTE).
Supplemental Table 2. BVAS univariate analysis, cyclophosphamide/rituximab use.
Supplemental Table 3. VDI univariate analysis.
Acknowledgments
This work was presented as a poster at the American Society of Nephrology Kidney Week on November 9, 2019 in Washington, DC.
Author Contributions
B. Antiochos, E. Gapud, D. Geetha, and B. Isaacs were responsible for methodology and resources; B. Antiochos, E. Gapud, D. Geetha, and P. Seo reviewed and edited the manuscript; E. Gapud, D. Geetha, B. Isaacs, and P. Seo were responsible for investigation; D. Geetha and B. Isaacs were responsible for data curation, project administration, validation, and visualization; D. Geetha, B. Isaacs, and P. Seo were responsible for formal analysis; D. Geetha was responsible for supervision; B. Isaacs was responsible for software; all authors conceptualized the study and wrote the original draft of the manuscript.
References
1. Stassen PM, Derks RPH, Kallenberg CGM, Stegeman CA: Venous thromboembolism in ANCA-associated vasculitis--incidence and risk factors. Rheumatology (Oxford) 47: 530–534, 2008
2. Zöller B, Li X, Sundquist J, Sundquist K: Risk of pulmonary embolism in patients with autoimmune disorders: A nationwide follow-up study from Sweden. Lancet 379: 244–249, 2012
3. Merkel PA, Lo GH, Holbrook JT, Tibbs AK, Allen NB, Davis JC Jr, Hoffman GS, McCune WJ, St Clair EW, Specks U, Spiera R, Petri M, Stone JH; Wegener’s Granulomatosis Etanercept Trial Research Group: Brief Communication: High incidence of venous thrombotic events among patients with Wegener Granulomatosis: The Wegener’s clinical occurrence of Thrombosis (WeCLOT) study. Ann Intern Med 142: 620–626, 2005
4. Hilhorst M, Winckers K, Wilde B, van Oerle R, ten Cate H, Tervaert JWC: Patients with antineutrophil cytoplasmic antibodies associated vasculitis in remission are hypercoagulable. J Rheumatol 40: 2042–2046, 2013
5. Allenbach Y, Seror R, Pagnoux C, Teixeira L, Guilpain P, Guillevin L; French Vasculitis Study Group: High frequency of venous thromboembolic events in Churg-Strauss syndrome, Wegener’s granulomatosis and microscopic polyangiitis but not polyarteritis nodosa: A systematic retrospective study on 1130 patients. Ann Rheum Dis 68: 564–567, 2009
6. Kronbichler A, Leierer J, Leierer G, Mayer G, Casian A, Höglund P, Westman K, Jayne D; European Vasculitis Society: Clinical associations with venous thromboembolism in anti-neutrophil cytoplasm antibody-associated vasculitides. Rheumatology (Oxford) 56: 704–708, 2017
7. Morgan MD, Turnbull J, Selamet U, Kaur-Hayer M, Nightingale P, Ferro CJ, Savage CO, Harper L: Increased incidence of cardiovascular events in patients with antineutrophil cytoplasmic antibody-associated vasculitides: A matched-pair cohort study. Arthritis Rheum 60: 3493–3500, 2009
8. Kronbichler A, Leierer J, Shin JI, Merkel PA, Spiera R, Seo P, Langford CA, Hoffman GS, Kallenberg CGM, St Clair EW, Brunetta P, Fervenza FC, Geetha D, Keogh KA, Monach PA, Ytterberg SR, Mayer G, Specks U, Stone JH; RAVE−ITN Research Group: Association of pulmonary hemorrhage, positive proteinase 3, and urinary red blood cell casts with venous thromboembolism in antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Rheumatol 71: 1888–1893, 2019
9. Emmi G, Silvestri E, Squatrito D, Amedei A, Niccolai E, D’Elios MM, Della Bella C, Grassi A, Becatti M, Fiorillo C, Emmi L, Vaglio A, Prisco D: Thrombosis in vasculitis: From pathogenesis to treatment. Thromb J 13: 15, 2015
10. Bautz DJ, Preston GA, Lionaki S, Hewins P, Wolberg AS, Yang JJ, Hogan SL, Chin H, Moll S, Jennette JC, Falk RJ: Antibodies with dual reactivity to plasminogen and complementary PR3 in PR3-ANCA vasculitis. J Am Soc Nephrol 19: 2421–2429, 2008
11. Abu-Fanne R, Stepanova V, Litvinov RI, Abdeen S, Bdeir K, Higazi M, Maraga E, Nagaswami C, Mukhitov AR, Weisel JW, Cines DB, Higazi AA: Neutrophil α-defensins promote thrombosis
in vivo by altering fibrin formation, structure, and stability. Blood 133: 481–493, 2019
12. Halbwachs L, Lesavre P: Endothelium-neutrophil interactions in ANCA-associated diseases. J Am Soc Nephrol 23: 1449–1461, 2012
13. Jennette JC, Falk RJ, Bacon PA, Basu N, Cid MC, Ferrario F, Flores-Suarez LF, Gross WL, Guillevin L, Hagen EC, Hoffman GS, Jayne DR, Kallenberg CG, Lamprecht P, Langford CA, Luqmani RA, Mahr AD, Matteson EL, Merkel PA, Ozen S, Pusey CD, Rasmussen N, Rees AJ, Scott DG, Specks U, Stone JH, Takahashi K, Watts RA: 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis Rheum 65: 1–11, 2013
14. Stone JH, Hoffman GS, Merkel PA, Min YI, Uhlfelder ML, Hellmann DB, Specks U, Allen NB, Davis JC, Spiera RF, Calabrese LH, Wigley FM, Maiden N, Valente RM, Niles JL, Fye KH, McCune JW, St Clair EW, Luqmani RA; International Network for the Study of the Systemic Vasculitides (INSSYS): A disease-specific activity index for Wegener’s granulomatosis: Modification of the Birmingham Vasculitis Activity Score. International Network for the Study of the Systemic Vasculitides (INSSYS). Arthritis Rheum 44: 912–920, 2001
15. Exley AR, Bacon PA, Luqmani RA, Kitas GD, Gordon C, Savage COS, Adu D: Development and initial validation of the Vasculitis Damage Index for the standardized clinical assessment of damage in the systemic vasculitides. Arthritis Rheum 40: 371–380, 1997
16. Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF 3rd, Feldman HI, Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J; CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration): A new equation to estimate glomerular filtration rate [published correction appears in
Ann Intern Med 155: 408, 2011]. Ann Intern Med 150: 604–612, 2009
17. Mendoza CE, Brant EJ, McDermott ML, Froment A, Hu Y, Hogan SL, Jennette JC, Falk RJ, Nachman PH, Derebail VK, Bunch DO: Elevated microparticle tissue factor activity differentiates patients with venous thromboembolism in anti-neutrophil cytoplasmic autoantibody vasculitis. Kidney Int Rep 4: 1617–1629, 2019
18. Petermann Smits DR, Wilde B, Kianersi adegani M, De jongh H, Van paassen P, Cohen Tervaert JW: Metabolic syndrome in anca-associated vasculitis. Rheumatol (United Kingdom) 52: 197–203, 2013
19. Jørgensen KA, Stoffersen E: On the inhibitory effect of albumin on platelet aggregation. Thromb Res 17: 13–18, 1980
