Raised Fibrinogen Levels and Outcome in Outpatients With Peripheral Artery Disease

Mendelian randomization assessing causal relationship between fibrinogen levels and ischemic stroke

OBJECTIVE

High fibrinogen levels are associated with an increased risk of ischaemic stroke (IS). We used mendelian randomisation (MR) to explore a potential causal relationship.

MATERIALS AND METHODS

Data for assessing the relationship between gene variant, disease and biological levels needed for a MR approach was collected using a meta-analytical approach. Inverse-variance weighted (IVW) approach was used for the main analyses and alternative approach for sensitivity analyses. The relationship between fibrinogen levels and IS was assessed using Odds Ratio (OR), while mean difference (g/L) was used for the relationship between SNP (rs1800790) and fibrinogen levels.

RESULTS

The variant FGB rs1800790 SNP was interrogated as an instrumental variable of fibrinogen levels. A meta-analysis with 24 studies (12 case-control and 12 cohort studies, totalling 20,902 cases and 76,510 controls was conducted. Homozygotes (AG) of rs1800790 have 0.14g/L (95%CI: 0.08-0.19, P<0.001) and minor allele (AA) have 0.18g/L (95%CI: 0.01-0.35, P=0.037) higher levels of plasma fibrinogen concentration compared with homozygous for the major allele (GG). The risk of IS was significantly increased in 1-g/L (OR=1.83, 95%CI: 0.92-3.62, P=0.084), or 1-SD of fibrinogen levels (OR=1.39, 95%CI: 1.03-1.87, P=0.030), or above median levels (OR=1.22, 95%CI: 1.02-1.46, P=0.029) or categorical levels tertiles (OR=1.50, 95%CI: 1.26-1.79, P<0.001). Each 1-g/L increase in fibrinogen levels was causally associated with a higher risk of ischemic stroke (OR=2.28, 95%CI: 1.53-3.03, P<0.001) in the Mendelian randomisation analysis.

CONCLUSIONS

Elevated fibrinogen levels are a causative risk factor for ischaemic stroke with each 1g/L increase doubling its risk.

Diuretics and risk of major adverse limb events in patients with type-2 diabetes: An observational retrospective study

AIM

In patients with type-2 diabetes mellitus (T2DM), sodium-glucose co-transporter 2 inhibitors are suspected to increase the risk of amputation. "Traditional" diuretics may increase major adverse limb events (MALEs), but the evidence is weak. We studied the association between common diuretics (i.e. thiazides, loop- and potassium-sparing diuretics) and MALEs/amputations in patients with T2DM.

METHODS

Consecutive T2DM patients without cardiovascular history referred to our center for cardiovascular check-ups were retrospectively studied. Follow-up data on MALEs were collected. We used Cox models to assess the association between diuretics and MALEs, or amputation alone. A propensity score with inverse probability of diuretic treatment weighting (IPTW) analysis was performed.

RESULTS

We studied 1309 patients, (59.5 ± 10.7 years, 51 % females) with diabetes duration of 9.1 ± 8.5 years, among whom 402 (30 %) were taking diuretics. During a follow-up of 3.8 ± 1.64 years, 121 (9.1 %) had MALEs, including 19 (1.4 %) amputations. Death occurred in 111 patients and the proportion of death was significantly different between groups: patients with diuretics n = 49, 44.1% vs patients without diuretics n = 62, 55.9 %, P = 0.001. Diuretics, in multivariable analysis, were associated with MALEs (aHR[95 %CI] 1.96[1.32;2.91] P = 0.001), even after adjustment on propensity score (aHR 1.66[1.08;2.56] P = 0.02) and IPTW analysis (aHR 1.76[1.67;1.84] P < 0.0001). This risk was particularly increased in case of an abnormal ankle-brachial index (aHR 2.29[1.32;3.96], P = 0.003) at baseline. Looking at diuretic classes separately, the adjusted risk was increased with loop diuretics (aHR 2.56[1.16;5.64] P = 0.020), thiazides (aHR 2.21[1.37;3.57] P = 0.001) or potassium sparing diuretics (aHR 2.56[1.16;5.64] P = 0.020).

CONCLUSION

Diuretic treatment weighting may be associated with increased risk of MALEs. We identified several markers of increased risk of limb events where the use of diuretics should be considered with caution.

Computational analysis to comprehend the structure-function properties of fibrinolytic enzymes from Bacillus spp for their efficient integration into industrial applications

Background

The fibrinolytic enzymes from Bacillus sp. are proposed as therapeutics in preventing thrombosis. Computational-based analyses of these enzymes' amino acid composition, basic physiological properties, presence of functional domain and motifs, and secondary and tertiary structure analyses can lead to developing a specific enzyme with improved catalytic activity and other properties that may increase their therapeutic potential.

Methods

The nucleotide sequences of fibrinolytic enzymes produced by the genus Bacillus and its corresponding protein sequences were retrieved from the NCBI database and aligned using the PRALINE programme. The varied physiochemical parameters and structural and functional analysis of the enzyme sequences were carried out with the ExPASy-ProtParam tool, MEME server, SOPMA, PDBsum tool, CYS-REC tool, SWISS-MODEL, SAVES servers, TMHMM program, GlobPlot, and peptide cutter software. The assessed in-silico data were compared with the published experimental results for validation.

Results

The alignment of sixty fibrinolytic serine protease enzymes (molecular mass 12-86 kDa) sequences showed 49 enzymes possess a conserved domain with a catalytic triad of Asp196, His242, and Ser569. The predicted instability and aliphatic indexes were 1.94-37.77, and 68.9-93.41, respectively, indicating high thermostability. The random coil means value suggested the predominance of this secondary structure in these proteases. A set of 50 amino acid residues representing motif 3 signifies the Peptidase S8/S53 domain that was invariably observed in 56 sequences. Additionally, 28 sequences have transmembrane helices, with two having the most disordered areas, and they pose 25 enzyme cleavage sites. A comparative analysis of the experimental work with the results of in-silico study put forward the characteristics of the enzyme sequences JF739176.1 and MF677779.1 to be considered when creating a potential mutant enzyme as these sequences are stable at high pH with thermostability and to exhibit αβ-fibrinogenase activity in both experimental and in-silico studies.

Differential gene expression patterns in ST-elevation Myocardial Infarction and Non-ST-elevation Myocardial Infarction

The ST-elevation Myocardial Infarction (STEMI) and Non-ST-elevation Myocardial Infarction (NSTEMI) might occur because of coronary artery stenosis. The gene biomarkers apply to the clinical diagnosis and therapeutic decisions in Myocardial Infarction. The aim of this study was to introduce, enrich and estimate timely the blood gene profiles based on the high-throughput data for the molecular distinction of STEMI and NSTEMI. The text mining data (50 genes) annotated with DisGeNET data (144 genes) were merged with the GEO gene expression data (5 datasets) using R software. Then, the STEMI and NSTEMI networks were primarily created using the STRING server, and improved using the Cytoscape software. The high-score genes were enriched using the KEGG signaling pathways and Gene Ontology (GO). Furthermore, the genes were categorized to determine the NSTEMI and STEMI gene profiles. The time cut-off points were identified statistically by monitoring the gene profiles up to 30 days after Myocardial Infarction (MI). The gene heatmaps were clearly created for the STEMI (high-fold genes 69, low-fold genes 45) and NSTEMI (high-fold genes 68, low-fold genes 36). The STEMI and NSTEMI networks suggested the high-score gene profiles. Furthermore, the gene enrichment suggested the different biological conditions for STEMI and NSTEMI. The time cut-off points for the NSTEMI (4 genes) and STEMI (13 genes) gene profiles were established up to three days after Myocardial Infarction. The study showed the different pathophysiologic conditions for STEMI and NSTEMI. Furthermore, the high-score gene profiles are suggested to measure up to 3 days after MI to distinguish the STEMI and NSTEMI.

Association between fibrinogen level and length of stay in patients with lower extremity atherosclerotic disease: a retrospective cohort study

The level of fibrinogen in patients with lower extremity atherosclerosis (LEAD) has been widely identified as a risk factor contributing to adverse outcomes. However, some knowledge gaps remain regarding fibrinogen levels and downstream adverse outcomes, such as length of stay (LOS). We conducted this study to examine the association between fibrinogen level and LOS in LEAD patients. The retrospective cohort study included 1428 LEAD patients between January 2014 and November 2021 in China. Several generalized linear models with a negative binomial link function were used to evaluate the association between fibrinogen level and LOS. The area under the curve (AUC) was used to evaluate the predicting effect of fibrinogen level on a LOS greater than 10 days (median LOS). The median age of the patients was 70 years old, and 1153 (80.74%) were males. Fibrinogen level was positively associated with LOS (β = 1.14; 95% CI, 0.42-1.86; p = 0.002) in LEAD patients after controlling for age, gender, number of historical hospitalizations, surgical history, vascular disease history, drinking history, smoking history, insurance type, surgical approach, lesion site, weight loss, Fontaine classification, age-adjusted Charlson comorbidity index, urea, total protein, activated partial thromboplastin time, thrombin time, prothrombin time-international normalized ratio, calcium, triglyceride, albumin/globulin ratio, phosphorus, and D-dimer. The fibrinogen-added prediction model demonstrated good discrimination and calibration, with an AUC value of 0.807. Fibrinogen level was positively associated with LOS in LEAD patients. The fibrinogen level is a widely available and easy-to-measure biochemical indicator, and it could be used as a suitable indicator for the prognosis and prophylaxis of prolonged LOS in patients with LEAD during hospitalization.

Risk of amputation under diuretics in patients with or at risk of lower extremity arterial disease: A systematic review and meta-analysis

BACKGROUND

Recently, increased risk of amputation under sodium glucose cotransporter-2 inhibitors has been debated. Similar concerns have been raised with other "traditional" diuretics, more particularly in patients with or at risk of lower extremity arterial disease (LEAD).

AIM

To collect all available data on any potential risk of amputation associated with diuretics in patients with or at risk of LEAD. Additionally, we looked for other limb-related events in these patients.

METHODS

We searched in PubMed, Embase and Scopus databases up to February 2021 for references, using peripheral or lower extremity arterial disease, diuretics and amputation keywords, excluding case reports, experimental animal studies and non-English reports.

RESULTS

Among the 1376 hits identified in the databases, six studies were finally included in this review, including one cross-sectional and five longitudinal studies (total of 47,612 participants). One study was limited to thiazide diuretics, one focused on loop diuretics and the remainder mixed all diuretics. All studies reported a significant association between diuretic use and amputation risk in patients with or at high risk of LEAD. Despite some limitations in several studies, the meta-analysis showed an increased risk of amputation associated with diuretics (odds ratio: 1.75, 95% confidence interval: 1.53-1.99; P<0.001). Beyond amputation, patients with or at risk of LEAD under diuretics appeared to be at increased risk of other lower limb events, mostly in the presence of other comorbidities, including diabetes.

CONCLUSIONS

Although the amount of data in the literature is scarce, this first systematic review and meta-analysis favours an increased risk of amputation in patients with or at risk of LEAD under diuretics. Further prospective studies must be conducted to provide a better understanding of the mechanisms. Meanwhile, the use of diuretics in these patients should be parsimonious, considering alternatives whenever possible.

Inadequate response to antiplatelet therapy in patients with peripheral artery disease: a prospective cohort study

BACKGROUND

Patients with peripheral artery disease (PAD) are treated with preventive strategies to improve the cardiovascular risk. The incidence of cardiovascular events and mortality however remains high in PAD populations. We therefore aimed to better characterize PAD patients suffering from cardiovascular events and mortality in order to tailor preventive treatment.

METHODS

Between 2018 and 2020, 246 PAD outpatients (17 newly diagnosed, 229 with known PAD) were prospectively enrolled in this observational cohort study. Patient data and blood samples were collected after inclusion, and the primary composite endpoint (myocardial infarction, elective coronary revascularization, ischemic stroke, acute limb ischemia, mortality) was evaluated after one year. Secondary outcomes included platelet reactivity, measured using the VerifyNow assay, and medication adherence, assessed using the Morisky Medication Adherence Scale-8 (MMAS-8). Logistic regression models were used to identify associations between characteristics and the occurrence of events.

RESULTS

The cohort comprised 207 patients with claudication and 39 with chronic limb threatening ischemia. Twenty-six (10.6%) patients suffered from an event during follow-up. Prior myocardial infarction (OR 3.3 [1.4-7.7]), prior ischemic stroke (OR 4.5 [1.8-10.9]), higher levels of creatinine (OR 5.2 [2.2-12.6]), lower levels of high-density lipoprotein (OR 4.2 [1.5-10.6]) and lower haemoglobin levels (OR 3.1 [1.3-7.1]) were associated with events. Patients with events had more often high on-treatment platelet reactivity (HTPR) on aspirin (OR 5.9 [1.4-25.1]) or clopidogrel (OR 4.3 [1-19.3]). High adherence to medication was associated with the occurrence of events (OR 4.1 [1-18]).

CONCLUSIONS

Patients suffering from cardiovascular events and mortality were characterized by prior cardiovascular events as compared to patients who did not experience any events. Antiplatelet therapy was not optimally protective despite high medication adherence, and HTPR was independently associated with the occurrence of events. More research is needed on alternative treatment strategies such as dual antiplatelet therapy or combinations with anticoagulant drugs.

TRIAL REGISTRATION

The Medical Ethics Committee (METC) of the MUMC+ approved the study (NL63235.068.17) and the study was registered in the Netherlands Trial Register ( NTR7250 ).

The Role of the Coagulation System in Peripheral Arterial Disease: Interactions with the Arterial Wall and Its Vascular Microenvironment and Implications for Rational Therapies

Peripheral artery disease (PAD) is a clinical manifestation of atherosclerotic disease with a large-scale impact on the economy and global health. Despite the role played by platelets in the process of atherogenesis being well recognized, evidence has been increasing on the contribution of the coagulation system to the atherosclerosis formation and PAD development, with important repercussions for the therapeutic approach. Histopathological analysis and some clinical studies conducted on atherosclerotic plaques testify to the existence of different types of plaques. Likely, the role of coagulation in each specific type of plaque can be an important determinant in the histopathological composition of atherosclerosis and in its future stability. In this review, we analyze the molecular contribution of inflammation and the coagulation system on PAD pathogenesis, focusing on molecular similarities and differences between atherogenesis in PAD and coronary artery disease (CAD) and discussing the possible implications for current therapeutic strategies and future perspectives accounting for molecular inflammatory and coagulation targets. Understanding the role of cross-talking between coagulation and inflammation in atherosclerosis genesis and progression could help in choosing the right patients for future dual pathway inhibition strategies, where an antiplatelet agent is combined with an anticoagulant, whose role, despite pathophysiological premises and trials' results, is still under debate.

Elevated Serum Inflammatory Markers in Subacute Stroke Are Associated With Clinical Outcome but Not Modified by Aerobic Fitness Training: Results of the Randomized Controlled PHYS-STROKE Trial

Background: Inflammatory markers, such as C-reactive Protein (CRP), Interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha and fibrinogen, are upregulated following acute stroke. Studies have shown associations of these biomarkers with increased mortality, recurrent vascular risk, and poor functional outcome. It is suggested that physical fitness training may play a role in decreasing long-term inflammatory activity and supports tissue recovery.

Aim: We investigated the dynamics of selected inflammatory markers in the subacute phase following stroke and determined if fluctuations are associated with functional recovery up to 6 months. Further, we examined whether exposure to aerobic physical fitness training in the subacute phase influenced serum inflammatory markers over time.

Methods: This is an exploratory analysis of patients enrolled in the multicenter randomized-controlled PHYS-STROKE trial. Patients within 45 days of stroke onset were randomized to receive either four weeks of aerobic physical fitness training or relaxation sessions. Generalized estimating equation models were used to investigate the dynamics of inflammatory markers and the associations of exposure to fitness training with serum inflammatory markers over time. Multiple logistic regression models were used to explore associations between inflammatory marker levels at baseline and three months after stroke and outcome at 3- or 6-months.

Results: Irrespective of the intervention group, high sensitive CRP (hs-CRP), IL-6, and fibrinogen (but not TNF-alpha) were significantly lower at follow-up visits when compared to baseline (p all ≤ 0.01). In our cohort, exposure to aerobic physical fitness training did not influence levels of inflammatory markers over time. In multivariate logistic regression analyses, increased baseline IL-6 and fibrinogen levels were inversely associated with worse outcome at 3 and 6 months. Increased levels of hs-CRP at 3 months after stroke were associated with impaired outcome at 6 months. We found no independent associations of TNF-alpha levels with investigated outcome parameters.

Conclusion: Serum markers of inflammation were elevated after stroke and decreased within 6 months. In our cohort, exposure to aerobic physical fitness training did not modify the dynamics of inflammatory markers over time. Elevated IL-6 and fibrinogen levels in early subacute stroke were associated with worse outcome up to 6-months after stroke.

Clinical Trial Registration:ClinicalTrials.gov, NCT01953549.

Antithrombotic Therapy in Patients with Peripheral Artery Disease: A Focused Review on Oral Anticoagulation

Peripheral artery disease (PAD) is a major cause of morbidity and mortality but it is usually underdiagnosed and undertreated. Patients with PAD present dysregulated procoagulant, anticoagulant, and fibrinolytic pathways leading to arterial and venous thrombosis. The risk of several ischemic-related complications could be mitigated with appropriate antithrombotic therapy, which plays a central role in all types of PAD. For years, antiplatelets have been indicated in patients with symptomatic PAD or those who have undergone revascularization. Unfortunately, a non-negligible proportion of patients with PAD will suffer from adverse events during the follow-up, even despite proper medical therapies for the prevention of PAD complications. Thus, there is room for improving clinical outcomes in these patients. Given the implication of both, primary and secondary hemostasis in arterial thrombosis and the pathophysiology of PAD, the combination of antiplatelets and anticoagulants has emerged as a potential antithrombotic alternative to antiplatelets alone. In this narrative review article, we have highlighted the most recent evidence about antithrombotic therapy in PAD patients, with a special focus on oral anticoagulation. Certainly, COMPASS and VOYAGER PAD trials have shown promising results. Thus, rivaroxaban in combination with aspirin seem to reduce cardiovascular outcomes with a similar bleeding risk compared to aspirin alone. Nevertheless, results from real-world studies are needed to confirm these observations, and other trials will provide novel evidence about the safety and efficacy of emerging anticoagulant agents.

Role of Fibrinolytic Enzymes in Anti-Thrombosis Therapy

Thrombosis, a major cause of deaths in this modern era responsible for 31% of all global deaths reported by WHO in 2017, is due to the aggregation of fibrin in blood vessels which leads to myocardial infarction or other cardiovascular diseases (CVDs). Classical agents such as anti-platelet, anti-coagulant drugs or other enzymes used for thrombosis treatment at present could leads to unwanted side effects including bleeding complication, hemorrhage and allergy. Furthermore, their high cost is a burden for patients, especially for those from low and middle-income countries. Hence, there is an urgent need to develop novel and low-cost drugs for thrombosis treatment. Fibrinolytic enzymes, including plasmin like proteins such as proteases, nattokinase, and lumbrokinase, as well as plasminogen activators such as urokinase plasminogen activator, and tissue-type plasminogen activator, could eliminate thrombi with high efficacy rate and do not have significant drawbacks by directly degrading the fibrin. Furthermore, they could be produced with high-yield and in a cost-effective manner from microorganisms as well as other sources. Hence, they have been considered as potential compounds for thrombosis therapy. Herein, we will discuss about natural mechanism of fibrinolysis and thrombus formation, the production of fibrinolytic enzymes from different sources and their application as drugs for thrombosis therapy.

The Role of Circulating Biomarkers in Peripheral Arterial Disease

Peripheral arterial disease (PAD) of the lower extremities is a chronic illness predominantly of atherosclerotic aetiology, associated to traditional cardiovascular (CV) risk factors. It is one of the most prevalent CV conditions worldwide in subjects >65 years, estimated to increase greatly with the aging of the population, becoming a severe socioeconomic problem in the future. The narrowing and thrombotic occlusion of the lower limb arteries impairs the walking function as the disease progresses, increasing the risk of CV events (myocardial infarction and stroke), amputation and death. Despite its poor prognosis, PAD patients are scarcely identified until the disease is advanced, highlighting the need for reliable biomarkers for PAD patient stratification, that might also contribute to define more personalized medical treatments. In this review, we will discuss the usefulness of inflammatory molecules, matrix metalloproteinases (MMPs), and cardiac damage markers, as well as novel components of the liquid biopsy, extracellular vesicles (EVs), and non-coding RNAs for lower limb PAD identification, stratification, and outcome assessment. We will also explore the potential of machine learning methods to build prediction models to refine PAD assessment. In this line, the usefulness of multimarker approaches to evaluate this complex multifactorial disease will be also discussed.

The Impact of platelet-fibrin clot strength on occurrence and clinical outcomes of peripheral artery disease in patients with significant coronary artery disease

Patients with peripheral artery disease (PAD) have shown the increased risk of cardiovascular (CV) morbidity and mortality. This study sought to evaluate the impact of clot strength on prevalence and major adverse CV events (MACE) of PAD in high-risk patients. We enrolled patients undergoing percutaneous coronary intervention (PCI) (n = 1667) with available platelet-fibrin clot strength [thrombin-induced maximal amplitude (MAthrombin) measured by thromboelastography] and inflammation [high sensitivity C-reactive protein (hs-CRP)]. PAD was defined with abnormal ankle-brachial index (≤ 0.9 or > 1.4). MACE was defined as a composite of CV death, myocardial infarction or stroke. PAD was observed in 201 patients (12.1%). In the multivariate analysis, high clot strength [MAthrombin ≥ 68 mm: odds ratio (OR) 1.70, 95% confidence interval (CI) 1.20 to 2.41, p = 0.003] and enhanced inflammation (hs-CRP ≥ 3.0 mg/L: OR 2.30, 95% CI 1.56 to 3.41, p < 0.001) were associated with PAD occurrence. During the follow-up post-PCI (median, 25 months), MACE was more frequently occurred in patients with vs. without PAD (18.7% vs. 6.4% at 3 years; hazard ratio 1.72, 95% CI 1.03 to 2.87, p = 0.039). Furthermore, combined presence of PAD and high clot strength significantly increased the risk of MACE. In conclusion, this study is the first to show the impact of clot strength on prevalence and clinical outcomes of PAD in coronary artery disease patients undergoing PCI. Whether antithrombotic strategy according to level of this biomarker can improve clinical outcomes in PAD patients deserves the further study.

An integrated platform for fibrinogen quantification on a microfluidic paper-based analytical device

Fibrinogen (FIB) plays a key role in blood coagulation and thrombosis and its concentration in blood can directly reflect health conditions, thus efficient detection of FIB would benefit the treatments of certain diseases such as liver and heart diseases. However, there is a lack of sensitive, simple, rapid and cheap FIB detection device currently, in lieu of expensive and sophisticated approaches in laboratories. Here, we propose a novel plasma separation and FIB detection platform based on a microfluidic paper-based analytical device (μPAD). It is the first time that dielectrophoretic (DEP) force is combined with capillary force on paper for plasma separation, and the separation efficiency of plasma reaches about 95%, ensuring reliable downstream FIB detection, for which we also propose a new method called the resistance-fibrinogen detection (RFD) method. It not only avoids the use of large-scale instruments for detection, but also possesses high precision and simplicity. The method is found to be reliable in FIB detection for various concentrations ranging from 127.0 to 508.0 mg dL^-1. Moreover, the results obtained from the proposed μPAD show an excellent agreement (R² = 0.9985) with those obtained from an automatic coagulation analyzer with natural human blood samples. Overall, the proposed platform provides a low-cost and reliable approach for FIB detection, especially for clinical use in resource-limited areas.

Plasma Biomarkers to Predict Cardiovascular Outcome in Patients With Peripheral Artery Disease: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

Patients with lower extremity peripheral artery disease (PAD) are at increased risk of major adverse cardiovascular events. Numerous plasma biomarkers have been investigated in lower extremity PAD, but none are used for clinical risk assessment. We aimed to provide a comprehensive overview of biomarker testing in PAD as a first step to improve risk stratification.

Predictors of responders to mononuclear stem cell-based therapeutic angiogenesis for no-option critical limb ischemia

Background

Although the mononuclear cell (MNC) transplantation could theoretically induce therapeutic angiogenesis in the patients with no-option critical limb ischemia (NO-CLI), the clinical responses to this approach are inconsistent among different clinical trials. The purpose of this study was to identify the prognostic factors of responders and develop a predictive nomogram to guide patient selection.

Methods

We retrospectively reviewed a consecutive NO-CLI cohort who received peripheral blood-derived transplantation in our center. The patients who survived and achieved complete remission of CLI at 6 months post-transplantation were defined as responders. Logistic regression models were used to screen and identify the prognostic factors based on which predictive nomogram was developed. A receiver operating characteristic (ROC) curve and a calibration curve were drawn to determine the discrimination level and predictive accuracy.

Results

The study ultimately enrolled 103 patients, including 58 responders and 45 non-responders. Based on the multivariate regression analysis, age ≥ 50 years (odds ratio [OR] 0.201, P = 0.004), blood fibrinogen > 4 g/L (OR 0.176, P = 0.003), arterial occlusion above the knee/elbow (OR 0.232, P = 0.010), the transcutaneous pressure of oxygen (TcPO₂) (OR 1.062, P = 0.006), and the Log total transplanted CD34⁺ cell count (OR 3.506, P = 0.046) were identified as independent prognostic factors of the responders in the nomogram. An area under the ROC curve of 0.851 indicated good discrimination, and the calibration curve of the predicted probability showed optimal agreement with that of the observed probability.

Conclusions

Age, blood fibrinogen, arterial occlusion level, TcPO₂, and the total transplanted CD34⁺ cell count were independent prognostic factors of the responders. A nomogram with high discrimination and accuracy was developed to provide individualized predictions.

Trail registration

ChiCTR, ChiCTR1800019401. Registered 9 November 2018—Retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1117-5) contains supplementary material, which is available to authorized users.

Hyperfibrinogenemia in Peripheral Arterial Disease: Coexistent and Independent Risk Factor (A Report of Two Cases and Review of Literature)

These case reports aim to show that hyperfibrinogenemia is a risk factor for the progression and prognosis of peripheral arterial disease (PAD), in patients with and without diabetes mellitus type 2. We present a patient with PAD who has type 2 diabetes mellitus, who has previously been repeatedly treated for lower limb ischemia with multiple vascular surgeries performed. A few weeks before admission the patient developed critical lower limb ischemia, which was treated with an iliaco-popliteal and femorofemoral bypass. The patient had elevated serum fibrinogen values. In the current admission, renewed left limb ischemia was diagnosed, and surgically evaluated with a recommendation for amputation of the left limb as a surgical recommendation. Our second patient had a stable intermittent claudication, dyslipidemia and hyperfibrinogenemia. He was successfully treated for those risk factors. Regular monitoring of the patient showed improved claudication distance and quality of life Our case reports, supported by a literature review, demonstrate that hyperfibrinogenemia is a possible risk factor for progression and the prognosis of PAD.