Immunosenescence and inflammatory markers in Cuban centenarians: implications for survival.

Centenarians are the best example of successful aging in humans. This work aimed to understand if immune status is associated with survival in Cuban centenarians. In a previous study, our group enrolled 43 centenarians and evaluated their immune status and functional capacity. 41 out of 43 recruited centenarians received follow-up phone calls, during a period of 2 years. Absolute CD4 + T cell count was higher among survivors, while the frequency of CD8 + CCR7-CD45RA + , CD8 + CD45RA + CD28-, and CD4 + CD28- T cells was higher among non-survivors. We also found that higher frequencies of terminally differentiated T cells were related to a higher risk of death, while centenarians with higher frequencies of T cells were more likely to survive. Surprisingly, neither serum inflammatory markers nor frailty/dependency was associated with survival. Our preliminary study suggests that immuno-senescence markers, but not inflammaging or functional capacity, are associated with survival beyond 100 years in a small group of Cuban centenarians.

Aging and chronic inflammation: highlights from a multidisciplinary workshop.

Aging is a gradual, continuous series of natural changes in biological, physiological, immunological, environmental, psychological, behavioral, and social processes. Aging entails changes in the immune system characterized by a decrease in thymic output of naïve lymphocytes, an accumulated chronic antigenic stress notably caused by chronic infections such as cytomegalovirus (CMV), and immune cell senescence with acquisition of an inflammatory senescence-associated secretory phenotype (SASP). For this reason, and due to the SASP originating from other tissues, aging is commonly accompanied by low-grade chronic inflammation, termed "inflammaging". After decades of accumulating evidence regarding age-related processes and chronic inflammation, the domain now appears mature enough to allow an integrative reinterpretation of old data. Here, we provide an overview of the topics discussed in a recent workshop "Aging and Chronic Inflammation" to which many of the major players in the field contributed. We highlight advances in systematic measurement and interpretation of biological markers of aging, as well as their implications for human health and longevity and the interventions that can be envisaged to maintain or improve immune function in older people.

Association among Terminally Differentiated T Cells, Frailty, and Dependency in a Group of Cuban Centenarians.

INTRODUCTION: Centenarians are considered a model of successful aging. Cuba exhibits one of the oldest populations in Latin America with more than two thousand centenarians. METHODS: This study aimed to evaluate the immune phenotype of forty-three Cuban centenarians, their clinical characteristics such as comorbidities, frailty, body mass index, and some hemochemical parameters. RESULTS: Centenarians had normal body mass indexes, relatively good health status, and 21.95% of them had no comorbidities; 53.6% were classified as frail, and 7% were classified as robust. In addition, 17% of centenarians were independent, and 41.46% were moderately dependent. The seroprevalence against cytomegalovirus was 100%. Concerning pro-inflammatory markers, the majority of them had very low cytokine levels and serum C-reactive protein around the normal limit. We also found the predominance of memory subsets over naive compartments in CD4+ and CD8+ T cells. Terminally differentiated CD8+CD28- T cells were higher in frail centenarians than in pre-frail, while CD8+CD57+ and CD8+EMRA T cells were higher in moderately and severely dependent individuals than in independent individuals. Severely dependent centenarians had a lower CD4+/CD8+ ratio. CONCLUSION: This study describes for the first time the predominance of memory subsets over naive compartments in CD4+ and CD8+ T cells, as well as its relation to frailty and/or dependency in a group of Cuban centenarians. Further studies are needed to continue understanding the natural biological aging mechanism and the relationship between terminally differentiated lymphocytes and inflammaging in the context of extreme longevity.

Immune, inflammatory and prothrombotic parameters in COVID-19 patients treated with an anti EGFR antibody.

SARS-CoV-2 infection causes a range of clinical presentations and induces changes in both innate and adaptive branches of the immune system. Furthermore, direct viral action to the cells of the lung promotes over-expression of the epidermal growth factor receptor (EGFR) which triggers pro-inflammatory response, contributes to coagulopathy and intravascular thrombi as well as lung fibrosis. Based on the role of this signaling pathway in the pathophysiology of the disease, nimotuzumab, an anti-EGFR monoclonal antibody, was used to treat patients with COVID-19. The aim of this study was to determine IL-6 and PAI-1 concentrations and lymphocyte subpopulations profiles in moderately and severely ill COVID-19 patients diagnosed during the B.1.617.2 variant wave in Cuba and included in a phase I/II trial to evaluate the safety and preliminary effect of nimotuzumab in COVID-19 disease. We observed high serum levels of IL-6, elevated plasma concentration of PAI-1, mean values of neutrophils to lymphocytes ratio (NLR) above three and CD4+ lymphopenia in both groups of patients. PAI-1 and IL-6 circulating levels decreased in patients treated with nimotuzumab. More than 95% of patients in which IL-6 decreased or increased slightly, were alive within 14 days after the monoclonal antibody administration. Patients with moderate and severe disease, were no different regarding the studied parameters, addressing the idea that several immune alterations could be present before the infection becomes clinically relevant. These findings suggest that nimotuzumab could be an attractive therapeutic option to interfere with the negative relationship between cytokines and procoagulant mediators in the inflammatory and prothrombotic phases of the disease.

Blocking EGFR with nimotuzumab: a novel strategy for COVID-19 treatment.

Background: Lung injury and STAT1 deficit induce EGFR overexpression in SARS-CoV-2 infection. Patients & methods: A phase I/II trial was done to evaluate the safety and preliminary effect of nimotuzumab, an anti-EGFR antibody, in COVID-19 patients. Patients received from one to three infusions together with other drugs included in the national guideline. Results: 41 patients (31 severe and 10 moderate) received nimotuzumab. The median age was 62 years and the main comorbidities were hypertension, diabetes and cardiovascular disease. The antibody was very safe and the 14-day recovery rate was 82.9%. Inflammatory markers decreased over time. Patients did not show signs of fibrosis. Conclusion: Nimotuzumab is a safe antibody that might reduce inflammation and prevent fibrosis in severe and moderate COVID-19 patients. Clinical Trial Registration: RPCEC00000369 (rpcec.sld.cu).

Background: After SARS-CoV-2 infection, many cells in the lung express a new receptor called EGFR. Overexpression of EGFR can worsen the pulmonary disease and provoke fibrosis. Patients & methods: The initial impact of using a drug that blocks EGFR, nimotuzumab, was evaluated in COVID-19 patients. Results: 41 patients received nimotuzumab by the intravenous route together with other medications. The median age was 62 years, and patients had many chronic conditions including hypertension, diabetes and cardiac problems. Treatment was well tolerated and 82.9% of the patients were discharged by day 14. Serial laboratory tests, x-rays and CT scan evaluations showed the improvement of the patients. Conclusion: Nimotuzumab is a safe drug that can be useful to treat COVID-19 patients.

Thymic Polypeptide Fraction Biomodulina T Decreases Exhausted and Terminally Differentiated EMRA T Cells in Advanced Lung Cancer Patients Treated With Platinum-Based Chemotherapy.

Lung cancer is the second cause of cancer related deaths worldwide. Chemotherapy and immunotherapy represent the current standard of care for advanced NSCLC. Platinum-based chemotherapy expands late-differentiated T cell populations. Therefore, immune restoration after chemotherapy to adjuvate the immunotherapeutic potential could be crucial. The aim of this study was to evaluate the effect of Biomodulina T (BT), a thymic polypeptide fraction, on peripheral lymphocytes subpopulations in the context of cancer disease. Additionally, whether these effects might induce a better response to CIMAvax-EGF, an epidermal growth factor (EGF) depleting immunotherapy. Eighteen advanced NSCLC patients were evaluated after being treated with platinum-based chemotherapy. We found that the frequency of terminally differentiated effector T cells re-expressing CD45RA (EMRA) CD4+ (p=0.0031) and CD8+ (p=0.0372) T cells decreased with the administration of BT, whereas CD4+ naive T cells increase in more than 70% of the patients. Remarkably, CD4+ and CD8+ T lymphocytes expressing programmed cell death receptor-1 (PD1) significantly decreased after BT administration (p=0.0005 and p<0.0001, respectively). We also found an enhancement of the anti-EGF antibody response with a large percentage of patients treated with CIMAvax-EGF reaching the good antibody response condition after four vaccine doses. Moreover, the median overall survival of patients treated with CIMAvax-EGF was 16.09 months. In conclusion, our results suggest that the immunorestoration generated by the administration of BT after first-line chemotherapy may induce a better immune response to CIMAvax-EGF that could translate into the clinical benefit of patients diagnosed with advanced NSCLC.

Nimotuzumab for COVID-19: case series.

Background: In COVID-19, EGFR production is upregulated in the alveolar epithelial cells. EGFR overexpression further activates STAT-3 and increases lung pathology. The EGFR pathway is also one of the major nodes in pulmonary fibrosis. Methods: Nimotuzumab, a humanized anti-EGFR antibody, was used to treat three patients with severe or moderate COVID-19. The antibody was administered in combination with other drugs included in the national COVID-19 protocol. Results: Nimotuzumab was well tolerated. IL-6 decreased from the first antibody infusion. Clinical symptoms significantly improved after nimotuzumab administration, and the CT scans at discharge showed major resolution of the lung lesions and no signs of fibrosis. Conclusion: Safe anti-EGFR antibodies like nimotuzumab may modulate COVID-19-associated hyperinflammation and prevent fibrosis. Clinical Trial Registration: RPCEC00000369 (RPCEC rpcec.sld.cu).

Lay abstract Background: In COVID-19, the protein EGFR is overactive in the infected lung cells. Methods: Nimotuzumab, an anti-EGFR antibody, was used to treat three patients with severe or moderate COVID-19. The antibody was administered in combination with other drugs included in the national COVID-19 protocol. Results: Nimotuzumab was safe. The most important inflammatory markers decreased from the first administration. The patients' clinical symptoms and imaging results improved significantly. Conclusion: Anti-EGFR antibodies like nimotuzumab may contribute to the recovery of COVID-19 patients without long-term consequences.

An anti-CD6 antibody for the treatment of COVID-19 patients with cytokine-release syndrome: report of three cases.

In COVID-19, the inflammatory cytokine-release syndrome is associated with the progression of the disease. Itolizumab is a monoclonal antibody that recognizes human CD6 expressed in activated T cells. The antibody has shown to be safe and efficacious in the treatment of moderate to severe psoriasis. Its effect is associated with the reduction of pro-inflammatory cytokines release, including IFN-γ, IL-6 and TNF-α. Here, we report the outcome of three severe and critically ill COVID-19 patients treated with itolizumab as part of an expanded access protocol. Itolizumab was able to reduce IL-6 concentrations in all the patients. Two of the three patients showed respiratory and radiological improvement and were fully recovered. We hypothesize this anti-inflammatory therapy in addition to antiviral and anticoagulant therapy could reduce COVID-19 associated morbidity and mortality.

Associations among cytokines, EGF and lymphocyte subpopulations in patients diagnosed with advanced lung cancer.

Aging is considered the single most significant risk factor for the majority of common malignances including lung cancer. Together immunosenescence, changes occurring with aging in the immune system, and inflammaging, characterizes by a chronic, subclinical accumulation of pro-inflammatory factors, are suggested to stand at the origin of most of the diseases of the elderly, such as cancer. The aim of this study was to determine associations among lymphocyte subpopulations, pro-inflammatory cytokines and epidermal growth factor (EGF) in patients diagnosed with non-small cell lung cancer (NSCLC). Forty-six advanced NSCLC patients were enrolled. Sixteen patients with newly diagnosed and before treatment and 30 patients after first-line platinum-based chemotherapy. Peripheral blood subpopulations were studied by flow cytometry and serum concentrations of soluble factors by ELISA. The frequency of naïve CD4+ T cells, naïve B cells and central memory CD8+ T cells were significantly lower in NSCLC patients after chemotherapy, while effector memory CD4+ T cells and terminally differentiated CD8+ T cells were significantly higher. IL-1ß and TNFα significantly correlated among them before and after platinum-based chemotherapy. Terminally differentiated T cells expressing CD57+ significantly correlated with TNFα and IL-1ß. For the first time, associations between EGF serum levels and terminally differentiated CD4+ T cells, and memory B cells were detected. This study confirms the association among terminally differentiated lymphocytes and pro-inflammatory cytokines in patients diagnosed with lung cancer, reinforcing the interconnection between terminally differentiated lymphocytes and pro-inflammatory cytokines. Clinical trial registration number: RPCEC00000205, http://registroclinico.sld.cu/.

An anti-CD6 monoclonal antibody (itolizumab) reduces circulating IL-6 in severe COVID-19 elderly patients.

BACKGROUND: Since the COVID-19 outbreak an unprecedented challenge for healthcare systems around the world has been placed. In Cuba, the first case of COVID-19 was reported on March 11. Elderly with multiple comorbidities have been the most risky population. Although most patients present a mild to moderate disease, some have developed severe symptoms. One of the possible mechanisms underlying rapid disease progression is a cytokine storm, in which interleukin (IL) -6 seems to be a major mediator. Itolizumab is a humanized recombinant anti-CD6 monoclonal antibody (MAb), with the ability of reducing serum interferon gamma (INF-γ), tumour necrosis factor alpha (TNFα) and IL-6. Based on these previous results in patients with psoriasis and rheumatoid arthritis, an expanded access clinical trial was approved by the Cuban regulatory agency for COVID-19 critically, severely and moderately ill patients. RESULTS: We show here a short kinetic of IL-6 serum concentration in the first 24 COVID-19 patients treated with itolizumab. Most of patients were elderly with multiple comorbidities. We found that with one itolizumab dose, the circulating IL-6 decreased in critically and severely ill patients, whereas in moderately ill patients the values didn't rise as compared to their low baseline levels. CONCLUSION: These findings suggest that itolizumab could be an attractive therapeutic option to decrease the negative outcome of the cytokine storm in COVID-19 patients. TRIAL REGISTRATION: CECMED IIC RD-EC 179, RPCEC00000311. Registered 4 May 2020 - Retrospectively registered, http://rpcec.sld.cu/ensayos/RPCEC00000311-Sp or http://rpcec.sld.cu/trials/RPCEC00000311-En.

El viroma humano. Implicaciones en la salud y enfermedad / The human virome. Its implications in health and disease

Introducción: El viroma humano se refiere al conjunto de todos los virus encontrados en el organismo humano. La diversidad viral del organismo humano bajo condiciones no patológicas ha sido subestimada. Se estima que hay 100 veces más virus en el cuerpo humano que células eucariotas. Objetivo: Realizar una revisión sistemática sobre las implicaciones del viroma humano para la salud y la enfermedad. Material y Métodos: Se realizó una revisión de artículos científicos publicados entre 2012 y 2017 en diversas bases de datos en línea. Se utilizaron en total 26 fuentes bibliográficas, incluidos artículos originales y revisiones. Desarrollo: Se presenta el conocimiento existente hasta el momento sobre las comunidades virales encontradas en diferentes sitios anatómicos como el sistema digestivo, respiratorio, genitourinario y sangre, los bacteriófagos y los Anellovirus son los virus más frecuentemente detectados. Si bien se hace evidente que el viroma tiene un papel tanto en el mantenimiento de la salud como en la enfermedad, estos mecanismos aún no se han esclarecido. Conclusiones: El organismo humano tiene una alta diversidad viral incluso bajo condiciones no patológicas. Aunque mucho se desconoce aún sobre las implicaciones del viroma, los avances en este campo abren nuevas perspectivas en la biomedicina(AU)

Introduction: The human virome refers to the collection of all viruses found in the human body. The viral diversity of the human body under non-pathological conditions has been underestimated. It is estimated that there are 100 times more viruses in the human body than eukaryotic cells. Objective: To carry out a systematic review of the human virome and its implications in health and disease. Materials and Methods: A review of scientific papers published between 2012 and 2017 in different online databases was made. A total of 26 bibliographic sources were used, including both original articles and reviews. Development: We present the existing knowledge to date about the viral communities found in different anatomical sites such as the digestive, respiratory, and genitourinary systems and the bloodstream; being the bacteriophages and Anellovirus the most frequently detected viruses. Although it is clear that the human virome plays a role both in maintaining health and in disease, these mechanisms have not yet been clarified. Conclusions: The human body has a high viral diversity even under non-pathological conditions. Although much is still unknown about the implications of these viruses on health and disease, advances in this field open new perspectives in the world of biomedicine(AU)

HIV-1 Antiretroviral Resistance in Cuba, 2009-2014.

INTRODUCTION By the end of 2017, there were more than 28,000 individuals living with HIV in Cuba, over 80% receiving antiretroviral therapy, which dramatically reduces viral replication, improves immune status and decreases risk of transmission. These results could be jeopardized by emergence of HIV-1 drug resistance. In 2009, a test for HIV-1 genotypic resistance was introduced in routine clinical practice in Cuba. OBJECTIVE Investigate antiretroviral resistance and its relation to subtype distribution in HIV-1 treatment-naïve and previously treated patients in Cuba. METHODS Resistance and HIV-1 subtype distribution were determined in 342 antiretroviral treatment-naïve patients and 584 previously treated for HIV-1 whose blood specimens were sent to the Pedro Kourí Tropical Medicine Institute during 2009-2014. Transmitted drug resistance was determined using the Calibrated Population Resistance Tool v.6. Drug resistance analysis was conducted using the algorithm Rega v9.1.0. RESULTS Prevalence of transmitted drug resistance was 11.4%, and 41% of mutated viruses exhibited dual-class resistance to nucleoside reverse transcriptase inhibitor and non-nucleoside reverse transcriptase inhibitor. Overall, 84.9% of patients had ≥1 resistance mutation, 80% had ≥1 nucleoside reverse transcriptase inhibitor mutation, 71.4% had ≥1 non-nucleoside reverse transcriptase inhibitor mutation and 31.7% had ≥1 protease inhibitor mutation. K65R and K101E mutations were significantly more frequent in subtype C, L210W in CRF19_cpx, and M47V/I in CRF BGs (20, 23, 24). Full class resistance to nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors and multidrug resistance were detected in 21.2%, 32.4%, 8% and 4.1% of patients, respectively. Average percentage resistance to nucleoside reverse transcriptase inhibitor, protease inhibitor, full class resistance to nucleoside reverse transcriptase inhibitor, protease inhibitor and multidrug resistance increased in patients failing two or more regimens. Nevertheless, after 2011, a declining trend was observed in the frequency of multidrug resistance and full class resistance to nucleoside reverse transcriptase inhibitors and protease inhibitors. CONCLUSIONS Detected levels of transmitted drug resistance highlight the need for a national surveillance study in treatment-naïve patients. Resistance prevalence is high in previously treated patients but appears to be decreasing over time. The frequency of resistance mutations in recombinant forms of HIV in Cuba needs further study. KEYWORDS Antiretroviral therapy, highly active antiretroviral therapy, HIV, anti-HIV agents, drug resistance, multiple drug resistance, Cuba.

Incidence of venous leg ulcer healing and recurrence after treatment with endovenous laser ablation.

BACKGROUND: The Effect of Surgery and Compression on Healing and Recurrence (ESCHAR) trial previously reported that patients with venous leg ulcers treated with saphenous stripping experienced a significantly reduced incidence of ulcer recurrence compared with patients treated with compression therapy. Most patients with leg ulcers and saphenous insufficiency are currently treated with endovenous thermal ablation (EVTA), but little information is available on the long-term results after EVTA in Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class 5 (C5) and class 6 (C6) patients. METHODS: We retrospectively reviewed all CEAP C5 or C6 patients treated with EVTA to define the incidence of ulcer healing and recurrence. Patients with active ulcers were managed weekly in a comprehensive wound center until healed. After healing, patients were treated with compression stockings and returned at 6-month intervals for follow-up. Time to healing and time to ulcer recurrence were determined by Kaplan-Meier survival analysis. Risk factors were assessed to determine their association with ulcer recurrence. RESULTS: EVTA of the great saphenous vein (n = 146), small saphenous vein (n = 20), or both (n = 7) was performed on 173 limbs with active (n = 72) or healed (n = 101) ulcers. Deep venous insufficiency was present in 54 cases (31.2%). Concomitant phlebectomy was performed in 59 limbs (34%). Median follow-up time was 25.2 months after EVTA. Venous ulcers healed after EVTA in 57% of cases at 3 months, 74% at 6 months, and 78% at 12 months. Ulcers recurred in 9% of patients at 1 year after EVTA, 20% at 2 years, and 29% at 3 years of follow-up. Ulcers recurred significantly more often in patients with deep venous insufficiency and in patients who did not undergo phlebectomy of associated varicose veins at the time of EVTA. CONCLUSIONS: Ulcers recurred in a minority of CEAP clinical C5 and C6 patients after EVTA of the saphenous veins. Ulcer recurrence was less frequent in patients without concomitant deep venous reflux and in those treated with phlebectomy of varicose veins at the time of EVTA. We suggest consideration of phlebectomy at the time of EVTA for patients with C5 and C6 venous insufficiency, particularly in those with isolated superficial venous insufficiency.

In vivo evaluation of safety and performance of a nitinol venous stent in an ovine iliac venous model.

BACKGROUND: Obstruction of the iliocaval venous outflow tract is a common cause of acute and chronic venous symptoms. Percutaneous stenting is now frequently performed to alleviate obstruction in the central venous system. However, currently used stents were primarily designed for biliary or arterial indications and may not be optimal for use in the venous system. This study evaluated the safety and performance of a novel venous stent (NVS) designed specifically for venous applications in an in vivo venous animal model. METHODS: The study evaluated vascular response and safety of the NVS compared with the Wallstent Stent (WS; Boston Scientific, Marlborough, Mass) at baseline, 56, and 180 days in adult sheep. Four sheep received a single NVS in the iliac vein for acute evaluation, and eight underwent bilateral iliac vein stenting using a single NVS on one side and a single WS on the other for longer-term follow-up. Fluoroscopy and intravascular ultrasound imaging were performed at implantation to identify iliac vein diameters at baseline and again at 56 and 180 days. Both iliac veins from all 56-day and 180-day animals (n = 16) underwent histologic examination. Three sections from each vessel were reviewed for intimal strut coverage, luminal thickening, thrombus, and evidence of venous injury. Student t-tests were used to compare mean iliac vein diameters for the WS and the NVS. RESULTS: Stent placement of the NVS and WS was successful to within 5 mm of the preselected location in all animals. During follow-up, no clinical evidence of stent thrombosis or obstruction >50% occurred in any limb. Sections of the stented vein at 56 and 180 days exhibited complete or nearly complete endothelial cell coverage, no or minimal luminal thrombus, and virtually complete neointimal coverage of every strut. The WS and NVS both caused an increase in iliac vein diameters immediately after stenting. At 180 days, there was no difference in iliac vein diameter or the percentage change in diameter compared with diameters immediately after stenting as measured by venography and intravascular ultrasound. CONCLUSIONS: In an ovine iliac vein model, a new NVS studied to 180 days was free of thrombotic complications and significant luminal stenosis. These data support clinical evaluation of this NVS in appropriately designed human clinical trials.

Current accepted hemodynamic criteria for critical limb ischemia do not accurately stratify patients at high risk for limb loss.

OBJECTIVE: Critical limb ischemia (CLI) has been defined as rest pain or tissue loss in patients who have an ankle-brachial index (ABI) ≤0.50, ankle pressure (AP) <70 mm Hg, or toe pressure (TP) <50 mm Hg. Data suggesting that these patients are at high risk for limb loss without successful revascularization are limited. This study was designed to identify limb loss and mortality rates in patients who did not respond to revascularization or who were not revascularized to determine whether CLI hemodynamic criteria accurately identify patients at high risk for limb loss. METHODS: Between 2008 and 2010, all patients undergoing lower extremity arterial duplex ultrasound testing at our hospital were identified. Those with ABI <0.50, AP <70 mm Hg, or TP <50 mm Hg were retrospectively reviewed to determine whether they had symptoms of rest pain, ischemic ulceration, or gangrene qualifying them for analysis in the database. Patients who underwent revascularization and subsequently had postrevascularization ABI, AP, or TP greater than the CLI criteria were removed from the cohort. Demographic factors, wound healing, amputation rates, and mortality were obtained and analyzed in relation to the initial APs and TPs. Outcomes were measured by Kaplan-Meier life-table analysis and Cox proportional hazards models. RESULTS: In 381 patients identified in the study, 443 limbs met CLI criteria. After revascularization, 98 limbs with ABI or TP that improved to >0.5 and >50 mm Hg, respectively, were removed from the study cohort. In 45 limbs, patients did not respond to initial revascularization as their ABI, AP, or TP remained within CLI criteria. These limbs remained in the patient cohort, yielding a final group of 296 patients and 345 limbs. Mean follow-up was 2 years. In the entire patient cohort, limb loss occurred in 24% at 1 year and in 31% at 3 years. Mortality was 32% at 1 year and 56% at 3 years. Amputation-free survival was 54% at 1 year and 28% at 3 years. Lower TPs were associated with a statistically higher incidence of amputation. Among those with an initial TP ≤10 mm Hg (n = 85), limb loss occurred in 46% at 1 year and 60% at 3 years. This limb loss was significantly greater than limb loss among those with a TP of 31 to 50 mm Hg (n = 115; 18% at 3 years; P < .001) Amputation-free survival in patients with a TP ≤10 mm Hg was 8% at 3 years. CONCLUSIONS: CLI is associated with a high mortality, but not all patients with currently defined hemodynamic criteria for CLI are at high risk of limb loss. Patients with a TP between 31 and 50 mm Hg (41% of the cohort) and not receiving revascularization or not responding hemodynamically to revascularization experienced a low risk of limb loss. We recommend revising the hemodynamic criteria for CLI to better identify patients at high risk for limb loss who require intervention to improve outcomes.