The need for outcome studies in type 2 diabetes

Outcome studies use primary end points such as overall mortality or major morbidity to demonstrate that treatments deliver meaningful clinical benefits. Historically it was thought that most of the cardiovascular morbidity due to diabetes was related to microvascular disease, providing a marker for macrovascular disease. In diabetes an outcome study would measure all-cause death, cardiac death and cardiovascular morbidity (end points related to macrovascular disease), whereas conventional trials in diabetes have used surrogate end points, such as blood pressure, microvascular disease (retinopathy, nephropathy) or glycaemic control, which may not predict clinical benefits in the prevention of macrovascular end points. Although outcome trials are increasingly required by regulatory or funding agencies, few have been performed in diabetes; most data have come from trials with surrogate end points or subgroup analyses of cardiovascular outcome trials. Methodological constraints, particularly the large patient populations and long follow-up required, partly explain the lack of outcome studies in diabetes.

The PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) is a macrovascular outcome study in patients with type 2 diabetes. It will involve approximately 4,000 patients who will receive pioglitazone or placebo in addition to their existing therapy. Principal end points will be all-cause mortality and severe disability due to macrovascular complications. PROactive should provide important data on the impact of therapy on the incidence of cardiovascular complications in type 2 diabetes.

Therapeutic angiogenesis for critical limb ischemia: design of the hepatocyte growth factor therapeutic angiogenesis clinical trial

The objective of the HGF-STAT clinical trial is to determine whether perfusion can be improved by gene transfer with a plasmid DNA containing hepatocyte growth factor (HGF) in the affected limb of patients with unreconstructable critical limb ischemia (CLI). CLI results in a high rate of limb loss and impaired quality of life. The current therapeutic strategies, including bypass surgery and percutaneous interventions, are only successful in treating a subset of patients. Therapeutic angiogenesis is an investigational method that seeks to favorably impact tissue per-fusion in CLI. HGF-STAT is a double-blind, parallel-group, placebo-controlled, dose response study in 100 patients with unreconstructable CLI. Eligible subjects will be randomized 1:1:1:1 to receive saline placebo or one of three dose/regimens of HGF plasmid DNA. The selection of outcome measures, including the primary endpoint, and changes in transcutaneous oxygen pressure (TcPO2) from baseline to 3 months will be discussed. In conclusion, this study will help to determine whether therapeutic angiogenesis with HGF is a viable option in the treatment of patients with CLI.

Review: PROactive 03: Pioglitazone, type 2 diabetes and reducing macrovascular events — economic implications?

conomic value of medicines, medical devices and other technologies is an increasingly important consideration in healthcare management. Conducting high quality economic analyses alongside randomised controlled clinical trials (RCTs) is desirable since these offer timely information with high internal validity. The recent publication of the landmark PROactive study provides a relevant platform upon which to base a detailed economic evaluation of the possible additional benefit of pioglitazone over and above current best treatment in patients with type 2 diabetes with severe cardiovascular (CV) disease. Pioglitazone improved CV outcome and reduced the need to add insulin to existing therapy in individuals at high risk of further macrovascular events. The predefined economic analysis of this study using well-accepted methods will inform the cost effectiveness (CE) of pioglitazone confirming (or not) its value in the management of patients with type 2 diabetes with severe CV disease.

An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries: A Supplement to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II): The TASC Steering Comittee(.)

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines were last updated in 2007 (TASC II) and represented the collaboration of international vascular specialties involved in the management of patients with peripheral arterial disease (PAD). Since the publication of TASC II, there have been innovations in endovascular revascularization strategies for patients with PAD. The intent of this publication is to provide a complete anatomic lower limb TASC lesion classification, including the infrapopliteal segment, and an updated literature review of new endovascular techniques and practice patterns employed by vascular specialists today.

An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries: A Supplement to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II)

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines were last updated in 2007 (TASC II) and represented the collaboration of international vascular specialties involved in the management of patients with peripheral arterial disease (PAD). Since the publication of TASC II, there have been innovations in endovascular revascularization strategies for patients with PAD. The intent of this publication is to provide a complete anatomic lower limb TASC lesion classification, including the infrapopliteal segment, and an updated literature review of new endovascular techniques and practice patterns employed by vascular specialists today.

An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines were last updated in 2007 (TASC II) and represented the collaboration of international vascular specialties involved in the management of patients with peripheral arterial disease (PAD). Since the publication of TASC II, there have been innovations in endovascular revascularization strategies for patients with PAD. The intent of this publication is to provide a complete anatomic lower limb TASC lesion classification, including the infrapopliteal segment, and an updated literature review of new endovascular techniques and practice patterns employed by vascular specialists today.

Results of the randomized, placebo-controlled clopidogrel and acetylsalicylic acid in bypass surgery for peripheral arterial disease (CASPAR) trial

OBJECTIVE

Dual antiplatelet therapy with clopidogrel plus acetylsalicylic acid (ASA) is superior to ASA alone in patients with acute coronary syndromes and in those undergoing percutaneous coronary intervention. We sought to determine whether clopidogrel plus ASA conferred benefit on limb outcomes over ASA alone in patients undergoing below-knee bypass grafting.

METHODS

Patients undergoing unilateral, below-knee bypass graft for atherosclerotic peripheral arterial disease (PAD) were enrolled 2 to 4 days after surgery and were randomly assigned to clopidogrel 75 mg/day plus ASA 75 to 100 mg/day or placebo plus ASA 75 to 100 mg/day for 6 to 24 months. The primary efficacy endpoint was a composite of index-graft occlusion or revascularization, above-ankle amputation of the affected limb, or death. The primary safety endpoint was severe bleeding (Global Utilization of Streptokinase and Tissue plasminogen activator for Occluded coronary arteries [GUSTO] classification).

RESULTS

In the overall population, the primary endpoint occurred in 149 of 425 patients in the clopidogrel group vs 151 of 426 patients in the placebo (plus ASA) group (hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.78-1.23). In a prespecified subgroup analysis, the primary endpoint was significantly reduced by clopidogrel in prosthetic graft patients (HR, 0.65; 95% CI, 0.45-0.95; P = .025) but not in venous graft patients (HR, 1.25; 95% CI, 0.94-1.67, not significant [NS]). A significant statistical interaction between treatment effect and graft type was observed (P(interaction) = .008). Although total bleeds were more frequent with clopidogrel, there was no significant difference between the rates of severe bleeding in the clopidogrel and placebo (plus ASA) groups (2.1% vs 1.2%).

CONCLUSION

The combination of clopidogrel plus ASA did not improve limb or systemic outcomes in the overall population of PAD patients requiring below-knee bypass grafting. Subgroup analysis suggests that clopidogrel plus ASA confers benefit in patients receiving prosthetic grafts without significantly increasing major bleeding risk.

Safety and tolerability of pioglitazone in high-risk patients with type 2 diabetes: an overview of data from PROactive

People with type 2 diabetes mellitus have an excess risk of macrovascular disease and a poorer prognosis. PROactive (PROspective pioglitAzone Clinical Trial In macroVascular Events) was a landmark study of secondary cardiovascular disease (CVD) prevention in type 2 diabetes that suggested a beneficial effect of pioglitazone therapy on macrovascular outcomes. Previous studies have already shown that pioglitazone has a good safety and tolerability profile in people with type 2 diabetes, but PROactive provided an opportunity to assess tolerability and safety associated with long-term exposure in a vulnerable subpopulation at very high cardiovascular risk. This review discusses all the key safety and tolerability characteristics associated with pioglitazone therapy in PROactive. As in previous studies, pioglitazone was associated with typical, but manageable, increases in oedema (26.4% vs 15.1% for placebo) and weight gain (mean change of +3.8 kg vs -0.6 kg for placebo). Increased hypoglycaemia with pioglitazone was consistent with improved glycaemic control. Despite more reports of serious heart failure in the pioglitazone group (5.7% vs 4.1% for placebo), there was a proportional improvement in macrovascular outcomes among patients developing heart failure, and absolute rates of macrovascular events and mortality were similar to those in the placebo group. Liver function tests confirmed the hepatic safety of pioglitazone with long-term use and revealed a tendency to improved hepatic function, which may reflect reductions in liver fat. The comparative incidence of malignancies was similar; however, more cases of bladder neoplasm (14 vs 5) and fewer cases of breast cancer (3 vs 11) were observed in the pioglitazone versus placebo arms of the study. A higher rate of bone fractures observed among pioglitazone-treated female patients (5.1% vs 2.5%) warrants further investigation. Overall, safety and tolerability was predictable, and adverse events were not treatment limiting. These results suggest that any beneficial effects of pioglitazone on macrovascular outcomes are accompanied by good long-term tolerability in this population of very high-risk patients with type 2 diabetes and established CVD.

Mediastinal mass mimicking a tumor in a patient with bladder cancer after Bacillus Calmette-Guerin treatment

We describe the case of a 78-year-old male with bladder cancer who developed a mediastinal mass after intravesical immunotherapy with live Mycobacterium bovis BCG. The clinical diagnosis was mediastinal tumor suggestive for lymphoma. However, cultures of the biopsy specimens grew an acid-fast organism, which was identified as M. bovis BCG. To the best of our knowledge, this is the first reported case in which a post-instillation BCG infection induced a mediastinal mass that mimicked a tumor in a patient with bladder cancer.

Effects of pioglitazone in patients with type 2 diabetes with or without previous stroke: results from PROactive (PROspective pioglitAzone Clinical Trial In macroVascular Events 04)

BACKGROUND AND PURPOSE

Diabetes is an important risk factor for stroke. We conducted analyses in patients who had entered the PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) with a history of stroke or without stroke.

METHODS

The prospective, double-blind PROactive (mean duration, 34.5 months) randomized 5238 patients with type 2 diabetes and a history of macrovascular disease to pioglitazone (titrated to 45 mg) or placebo, in addition to current diabetes and cardiovascular medications. Cardiovascular end-point events were independently adjudicated. This analysis evaluated the risk of stroke and other cardiovascular outcomes in patients with (n=984) and without (n=4254) prior stroke.

RESULTS

In patients with previous stroke (n=486 in the pioglitazone group and n=498 in the placebo group), there was a trend of benefit with pioglitazone for the primary end point of all-cause death, nonfatal myocardial infarction, acute coronary syndrome, and cardiac intervention (including coronary artery bypass graft or percutaneous coronary intervention), stroke, major leg amputation, or bypass surgery or leg revascularization (hazard ratio[HR]=0.78, event rate=20.2% pioglitazone vs 25.3% placebo; 95% CI=0.60-1.02; P=0.0670) and for the main secondary end point of all-cause death, nonfatal myocardial infarction, or nonfatal stroke (HR=0.78, event rate=15.6% pioglitazone vs 19.7% placebo; 95% CI=0.58-1.06; P=0.1095). Pioglitazone reduced fatal or nonfatal stroke (HR=0.53, event rate=5.6% pioglitazone vs 10.2% placebo; 95% CI=0.34-0.85; P=0.0085) and cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke (HR=0.72, event rate=13.0% pioglitazone vs 17.7% placebo; 95% CI=0.52-1.00; P=0.0467). Higher event rates were observed in patients with prior stroke compared with those without prior stroke. In patients without prior stroke, no treatment effect was observed for a first stroke.

CONCLUSIONS

In a subgroup analysis from PROactive, pioglitazone reduced the risk of recurrent stroke significantly in high-risk patients with type 2 diabetes.

PROactive 07: pioglitazone in the treatment of type 2 diabetes: results of the PROactive study

Patients with type 2 diabetes face an increased risk of macrovascular disease compared to those without. Significant reductions in the risk of major cardiovascular events can be achieved with appropriate drug therapy, although patients with type 2 diabetes remain at increased risk compared with non-diabetics. The thiazolidinedione, pioglitazone, is known to offer multiple, potentially antiatherogenic, effects that may have a beneficial impact on macrovascular outcomes, including long-term improvements in insulin resistance (associated with an increased rate of atherosclerosis) and improvement in the atherogenic lipid triad (low HDL-cholesterol, raised triglycerides, and a preponderance of small, dense LDL particles) that is observed in patients with type 2 diabetes. The recent PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) study showed that pioglitazone can reduce the risk of secondary macrovascular events in a high-risk patient population with type 2 diabetes and established macrovascular disease. Here, we summarize the key results from the PROactive study and place them in context with other recent outcome trials in type 2 diabetes.

The prevalence of thrombophilia in patients with symptomatic peripheral vascular disease

Background

The aim of this prospective study was to establish the prevalence of thrombophilia and hyperhomocysteinaemia using a comprehensive screen in patients with peripheral vascular disease.

Methods

A total of 150 patients with peripheral vascular disease (with an ankle brachial pressure index of less than 0·8) underwent thrombophilia screening (protein C and protein S, antithrombin, lupus anticoagulant, activated protein C resistance and factor V Leiden and prothrombin mutations). Fasting homocysteine assays were also performed.

Results

A thrombophilia defect was found in 41 patients (27·3 per cent). The commonest was protein S deficiency, found in 17 patients (11·3 per cent). Others included factor V Leiden mutation, found in 10 (6·7 per cent) and protein C deficiency, found in six (4·0 per cent). Lupus anticoagulant and prothrombin mutation were both found in six (4·0 per cent). One patient had an antithrombin deficiency. Only the presence of critical ischaemia was associated with a positive thrombophilia screen on single variable analysis (P = 0·03). Hyperhomocysteinaemia was present in over a third of the study group (37·3 per cent): 45 defined as moderate and 11 as intermediate.

Conclusion

A quarter of patients with peripheral vascular disease had evidence of thrombophilia, and a third had hyperhomocysteinaemia.

Parenteral therapy with lipo-ecraprost, a lipid-based formulation of a PGE1 analog, does not alter six-month outcomes in patients with critical leg ischemia

PURPOSE

Eicosanoids with vasodilating and angiogenic properties have been postulated to be effective therapies for critical leg ischemia (CLI) secondary to atherosclerotic peripheral arterial disease. The ability to deliver active drug to the site of action at adequate doses for sufficient duration has been a major limitation in the clinical development of such therapies. Lipo-ecraprost is a lipid-encapsulated prostaglandin E1 prodrug with the potential to deliver active prostaglandin to the site of critical arterial ischemia. The current trial was designed to test the hypothesis that lipo-ecraprost would improve amputation-free survival in patients with CLI who had no revascularization options.

METHODS

The study was randomized, multicenter, double blind, and placebo controlled. Patients who met clinical and hemodynamic criteria were randomized to receive placebo or lipo-ecraprost (60 microg) administered intravenously on each of 5 days per week, for a total of 8 weeks. The study's primary endpoint was the rate of a composite end point of death or amputation above the level of the ankle at 180 days (6 months).

RESULTS

The study was terminated on a recommendation from the Data and Safety Monitoring Board after the completion of a protocol-specified interim analysis for futility. At the time of termination, 383 of the planned 560 patients had been randomized, of which 379 received at least one dose of study medication and thus were included in the intention-to-treat population. Twenty-three patients were lost to follow-up and were not available for 6-month assessments. At 6 months of follow-up, there were 23 amputations in the 177 patients who received placebo, and 29 amputations in the 179 patients randomized to lipo-ecraprost. At 6 months, 10 deaths had occurred in the placebo group and 18 deaths had occurred in the lipo-ecraprost arm. Changes in lower-extremity hemodynamics over the 6-month study period did not differ between the placebo and lipo-ecraprost treatment arms.

CONCLUSION

Intensive treatment with lipo-ecraprost failed to modify the 6-month amputation rate in patients with CLI who were not candidates for revascularization.

Prevalence and Risk of Thrombophilia Defects in Vascular Patients

This paper reviews the available data on the prevalence of thrombophilia defects in patients with peripheral vascular disease (PVD) and attempts to delineate the risk of failure of vascular intervention in these patients. The prevalence of thrombophilia in stable claudicants is 25% and increases to 40% in those requiring revascularisation, compared to only 11% in the control group. The overall prevalence of thrombophilia defects in patients with premature atherosclerosis appears to be between 15 and 30%. The prevalence in the typical cohort of patients with PVD appears to be similar. All these studies have recruited patients with symptoms significant enough to warrant intervention. The overall prevalence of thrombophilia calculated from these trials, therefore, may not be truly indicative of the general vascular population who may not even present primary or secondary healthcare. The risk of thrombotic occlusion following arterial revascularisation in patients with an identified thrombophilia defect appears to be almost three times that of patients with no evidence of a thrombophilia defect. The best management of these patients has not been determined and needs to be evaluated by prospective randomized trials.

The prospective pioglitazone clinical trial in macrovascular events (PROactive): can pioglitazone reduce cardiovascular events in diabetes? Study design and baseline characteristics of 5238 patients

OBJECTIVE

The PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) assesses the effect of pioglitazone, a peroxisome proliferator-activated receptor agonist, with anti-inflammatory and vascular properties, on the secondary prevention of macrovascular events in type 2 diabetes.

RESEARCH DESIGN AND METHODS

PROactive is an on-going randomized, double-blind outcome study in patients with type 2 diabetes managed with diet and/or oral blood glucose-lowering drugs (combination of oral agents with insulin is permitted) who have a history of macrovascular disease. Patients are randomized to receive pioglitazone (forced titration from 15 to 30 to 45 mg, depending on tolerability) or placebo in addition to existing therapy. The primary end point is the time from randomization to occurrence of a new macrovascular event or death. Follow-up is estimated to span 4 years.

RESULTS

A total of 5238 patients have been randomized from 19 countries. At entry into the study, patients enrolled are a mean age of 61.8 years, with type 2 diabetes for a mean of 9.5 years; 60.9 and 61.5% are taking metformin or a sulfonylurea, respectively; and 33.6% are using insulin in addition to oral glucose-lowering drugs. The majority of patients are men (66.1%). Patients are required to meet one or more of entry criteria, as follows: >6 months' history of myocardial infarction (46.7%); coronary artery revascularization (30.8%), stroke (18.8%), or acute coronary syndrome for >3 months (13.7%); other evidence of coronary artery disease (48.1%); or peripheral arterial occlusive disease (19.9%). One-half (48.5%) of the patients have two or more of these risk factors. Three-quarters (75.4%) have hypertension, and 58.8% are current or previous smokers.

CONCLUSIONS

The cohort of patients enrolled in PROactive is a typical type 2 diabetic population at high risk of further macrovascular events. The characteristics of this population are ideal for assessing the ability of pioglitazone to reduce the cardiovascular risk of patients with type 2 diabetes.

A clinical approach to the management of a patient with suspected renovascular disease who presents with leg ischemia

Atherosclerotic renal artery stenosis (ARAS) may cause hypertension, progressive renal failure, and recurrent pulmonary edema. It typically occurs in high risk patients with coexistent vascular disease elsewhere. Most patients with ARAS are likely to die from coronary heart disease or stroke before end-stage renal failure occurs. Recent controlled trials have shown that most patients undergoing angioplasty to treat renovascular hypertension still need antihypertensive agents 6 or 12 months after the procedure. Nevertheless, the number of antihypertensive agents required to control blood pressure adequately is lower following angioplasty than for medication alone. Trials assessing the value of revascularization for preserving renal function or preventing clinical events are only in the early recruitment phase. Revascularization should be undertaken in patients with ARAS and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition. With or without revascularization, medical therapy using antihypertensive, hypolipidemic and antiplatelet agents is necessary in almost all cases.

Poor outcome following revascularization predicted by thromboelastography

Background

Infrainguinal revascularization procedures are associated with a high risk of graft failure, amputation and early death. Hypercoagulability predicts a poor overall outcome but conventional tests are expensive and results are not immediately available. A cheap, rapid method for identifying hypercoagulability would allow screening before revascularization. Thromboelastography (TEG) is a rapid, reliable, bedside method of assessing whole blood clotting. Normally used to assess hypocoagulability, this study determined the role of TEG in identifying patients with a poor prognosis following revascularization.

Methods

Between November 1998 and January 2000, 106 patients with critical leg ischaemia were admitted for radiological or surgical revascularization (mean age 71 (range 33–90) years). All underwent TEG analysis, standard thrombophilia screening (STS), and fasting homocysteine and fibrinogen assays. All patients were followed for 6 months after revascularization by means of clinical examination, ankle: brachial pressure index (ABPI) and duplex imaging.

Results

At the 6-month follow-up of 106 patients, 29 (27 per cent) had arterial or graft occlusion, five (5 per cent) had died and four (4 per cent) had undergone a major amputation. Analysis of risk factors revealed that a hypercoagulable TEG (P = 0·0009), STS and/or raised fibrinogen level (P = 0·01), and rest pain (P = 0·006) were associated with poor outcome. Other factors such as age, sex, diabetes, current or previous smoking, coronary artery or cerebrovascular disease, hypertension, previous intervention, aspirin or lipid-lowering therapy were not significantly different. In addition, hyperlipidaemia, hyperhomocysteinaemia, raised level of C-reactive protein, eyrthrocyte sedimentation rate, lipoprotein a level, haemocrit, STS or fibrinogen alone were not useful as predictors of poor outcome.

Conclusion

TEG, a rapid inexpensive test of hypercoagulability, is associated with poor outcome following infrainguinal revascularization.

Thromboelastography: a reliable test?

The thromboelastograph (TEG), a measure of global haemostasis, is routinely used during cardiac and hepatic surgery to optimize blood product selection and usage. It has recently been suggested that it may also be a useful tool to screen patients with hypercoagulable states. Limited published data on performance characteristics has led to speculation regarding its consistency and, therefore, validity of the results. This study was designed to assess the effect of stability of blood samples prior to testing, repeated sampling, intra- and inter-assay variability using the native, celite, tissue factor (TF) and Reopro-modified TEG. Analysis of native and celite samples after storage over 90 min showed a period of instability up to 30 min. Thereafter, all parameters between 30 and 90 min were stable [P = not significant (NS)]. When the same sample was repeatedly assayed, both native and celite TEG parameters showed a significant change towards hypercoagulability (P < 0.01), whereas the TF and Reopro-modified TEG showed no change. Intra- and inter-assay variability on samples tested after 30 min showed excellent reproducibility for all parameters (P = NS). The data suggest that the TEG is a useful tool in haemostasis but requires a formal standard operating procedure to be adopted that takes into account the initial period of sample instability.

A clinical approach to the management of the patient with coronary (Co) and/or carotid (Ca) artery disease who presents with leg ischaemia (Lis)

The purpose of this document is to provide the clinician with easy-to-use guidelines when faced with a patient with severe ischaemia in the limbs requiring interventional treatment; the CoCaLis document does not focus on the management of the lower limb ischaemia, but rather on the best possible approach to the associated coronary and/or carotid artery disease. The first part of the text deals with the epidemiological aspects of this condition followed by a description of, and proposals for, the management of risk factors. The next part deals with the approach to the coronary circulation and the carotid territory. In each part attention is mainly given to the practical aspects in terms of both diagnosis and treatment; for each of these steps the costs involved are considered and attention given to balancing the clinical decisions against the costs. The recommendations given are 'evidence based' when such evidence exists and, if not, the proposals are based on the consensus of the members of the group. In many instances it was apparent that the necessary information is not available in the literature. The authors hope that the CoCaLis document may not only improve the management of the vascular patient but also stimulate further research in this difficult clinical condition which carries a significantly increased risk for the patient.

Intermittent claudication: a condition with underrated risks

Intermittent claudication (IC) is a symptom of peripheral arterial occlusive disease (PAOD); it is subjective and therefore difficult to measure reliably. Both the WHO/Rose Questionnaire and the Edinburgh Questionnaire have been used widely, but they have a low sensitivity and therefore underestimate the true prevalence of IC. The addition of a clinical examination does not necessarily eliminate errors found on questionnaires alone. The single most important part of the physical examination to confirm a diagnosis of IC is the palpation of the patient's peripheral pulses, which alone appears to be more sensitive, but less specific, than the questionnaires. The most useful noninvasive test is the ankle-brachial pressure index (ABPI), and it has been suggested that a resting ABPI of 0.9 is up to 95% sensitive in detecting angiogram-positive disease, and almost 100% specific in identifying apparently healthy individuals. An ABPI of 0.9 or less is believed to be associated with 50% or greater vessel stenosis. The incidence of IC varies depending on the methodology used to define it, but there is a general pattern of a gradual increase in incidence up to the age of at least 70 years. For a chronic disease, the prevalence is a more relevant indicator of how common it is. The prevalence of IC is 3% to 6% in men aged 60 years and increases with age. The prevalence of asymptomatic PAOD may be as high as 20% in the adult population, using noninvasive testing. This is important because, as will be seen in later articles, PAOD, whether symptomatic or asymptomatic, is a serious risk factor for cardiovascular morbidity and mortality.

Major amputations: clinical patterns and predictors

The major amputation rate is approximately 200 to 500/million/yr and occurs in patients presenting with an acute onset of critical leg ischemia (CLI) rather than in patients who steadily progress through increasingly severe claudication to rest pain and ulcers. Diabetics, who form only 2% to 5% of the population, form 40% to 45% of all amputees. Although it is widely believed that a below-knee (BK) to above-knee (AK) amputation ratio of 2.5 is the minimum acceptable for units providing a lower limb amputation service, the ratio is in fact usually very much below the recommended figure. The data suggest that primary healing of BK amputations ranges from 30% to 92% and the reamputation rate from 4% to 30%. If a popliteal pulse is palpable, then there is only a 10% failure rate, and bleeding during the operation does not seem to predict healing. Of the 30% of BK amputees whose wounds do not heal primarily, about half will need a higher major amputation, but once a BK major amputation has healed, only 4% of such patients ever need a higher amputation. A total of 90% of AK major amputations heal, 70% primarily. Two to three times as many BK amputees achieve full mobility than AK amputees, and there has not been any dramatic change in 20 years. The fate of the amputee 2 years after a successful BK amputation will be that 15% will have been converted to an AK amputation, another 15% will have had a contralateral major amputation, and 30% will be dead.

The fate of patients with critical leg ischemia

In some highly specialized and aggressive units, 90% of patients with critical leg ischemia (CLI) will undergo some form of surgical or endovascular procedure; however, in most, the figure is nearer 50 to 60%. The primary amputation rate varies from around 10% to 40%. The mortality rate in these patients with standard therapy is around 20% at 1 year and between 40% and 70% at 5 years. Virtually all (95%) patients who present with ischemic gangrene, and 80% of those presenting with rest pain, are dead within 10 years. There appears to be a decline in overall major amputation rates associated with a corresponding increase in revascularizations. However, although technical advances may have resulted in a steadying or even decrease in amputations, comparisons of total amputations over a longer period suggest an increase, presumably attributable to an aging population. Some forward projections predict that major amputations will be doubled in the next 30 years.

Lower-extremity arteriosclerosis as a reflection of a systemic process: implications for concomitant coronary and carotid disease

Peripheral arterial occlusive disease (PAOD), coronary artery disease (CAD), and cerebrovascular disease (CVD) are all manifestations of atherosclerosis or atherothrombosis, and therefore it is not surprising that the three conditions commonly occur together. Knowledge of the magnitude of co-existing cardiovascular disease and its prognosis is essential for the physician treating IC so that he can treat the local disease in its systemic context. The prevalence of CAD in patients with IC is 40% to 60%, although this may be asymptomatic and increases with the severity of the PAOD. Not surprisingly, the converse is also true; among individuals with CAD, the prevalence of PAOD is higher than in non-CAD individuals. The link between PAOD and CVD seems to be weaker than that with CAD, but again up to 60% of claudicants have some evidence of CVD. The prevalence of patients with CVD increases as the ABPI decreases. The evidence available from all of the relevant studies suggests that approximately 60% of patients with PAOD will have significant disease in the cardiac or cerebral circulation, and approximately 40% of patients with coronary disease or significant cerebral circulatory disease also will have PAOD.

Predicting which patients will develop chronic critical leg ischemia

Although numerically far less than claudicants, patients with critical leg ischemia (CLI) demand a disproportionately large commitment both in medical effort and economically and represent the major workload for vascular surgical units. The incidence and prevalence of CLI is approximately 500 to 1,000/million/year. The risk factors for the development of CLI are largely the same as those for the progression of local disease in IC, the most important, apart from age, being smoking and diabetes. Major amputation is more common amongst claudicants who are heavy smokers and who continue to smoke, and although stopping smoking slows down the vascular changes and reduces the likelihood of symptomatic progression, it does not reduce the risk of major amputation over the following 2 to 3 years. Diabetic PAOD patients are about 10 times more likely to come to amputation than nondiabetic PAOD patients, and the prevalence of gangrene is 20 to 30 times higher in individuals with diabetes and PAOD compared with nondiabetics with PAOD. There is some evidence that most of these effects of risk factors are additive.

The natural history of claudication: risk to life and limb

Although a patient with intermittent claudication (IC) will fear progression to severe disease and amputation, this is a relatively rare outcome of claudication, with only 1% to 3% of claudicants ever requiring major amputation over a 5-year period. Indeed, in one study, 50% of claudicants became symptom free during 5 years' follow-up. All the new evidence over the last 40 years has not altered the impression that only about one fourth of patients with IC will ever significantly deteriorate, and that deterioration is most frequent during the first year after diagnosis (6 to 9%) compared with 2% to 3% per annum thereafter. Smoking is the most important risk factor for the progression of local disease in the legs, with an amputation rate 11 times greater in smokers than nonsmokers. Diabetes, male gender, and hypertension are also important risk factors for progression. Because cerebrovascular disease (CVD), coronary artery disease (CAD), and peripheral arterial occlusive disease (PAOD) coexist, PAOD and IC should be regarded as a marker for increased risk from fatal and nonfatal cardiovascular event, and 2% to 4% of claudicants have a nonfatal cardiovascular event every year. The risk is higher in the first year after developing IC than in a long-standing stable claudicant, and the average claudicant is more likely to have a nonfatal myocardial infarction (MI) or stroke in the next year that of ever requiring a major amputation for his leg ischemia. The mortality in claudicants is 30% at 5 years, 50% at 10 years, and 70% at 15 years, without any clear decrease in these figures over the last 30 to 40 years. The mortality of claudicants is approximately two and a half times that of an age-matched general population.

Predictors of early disease in the lower limbs

Increasing age and male gender are unavoidable risk factors for peripheral arterial occlusive disease (PAOD). A number of studies have looked at classical risk factors for atherosclerosis, such as diabetes, hypertension, lipid abnormalities, and smoking, as well as some more recently identified associations, such as plasma fibrinogen levels, impaired glucose tolerance, and hyperhomocysteinemia. However, most "risk factors" are really associations. A causal relationship may only reasonably be firmly established if a prospective controlled study shows that removing the risk factor significantly alters the course of the disease, as with smoking. Smoking is probably the strongest risk factor for intermittent claudication (IC), but hyperhomocysteinemia also appears to be strongly associated with the development of PAOD. Moderate alcohol intake and regular physical exercise appear to have a protective effect. A genetic risk factor is suggested but not as yet confirmed. The magnitude of the association varies from odds ratios of 2 to 3 for smoking and diabetes. There is insufficient evidence for hyperhomocysteinemia, but the effect may be even greater. The association with hypertension and lipid abnormalities is surprisingly inconclusive.

Acute limb ischemia

Although there is little information on the incidence of acute limb ischemia (ALI) in the general population, it is estimated to be 14 per 100,000 and to compose 10% to 16% of the vascular workload. Also, as surgical intervention has become an option for ALI, the numbers actually referred appear to be increasing. The two main causes of ALI are either an embolism or a thrombosis, and differentiation based on history and clinical examination alone may be clinically impossible in 10% to 15% of cases. However, with the advent of thrombolysis, the distinction between emboli and thrombotic occlusions has become less important from the point of view of management. The natural history of ALI has remained largely unchanged despite the advent of the Fogarty catheter and thrombolysis. Patients presenting with ALI continue to have a particularly severe short-term outlook both in terms of loss of the leg and mortality, with 30-day amputation rates of between 10% and 30% and a mortality rate of around 15%. A patient with an embolic cause for an ischemic leg is at a higher risk of death because of the associated underlying cardiac disease, whereas patients with a thrombotic cause are more likely to lose a limb. The fact that overall mortality rates after intervention for acute ischemia have not improved dramatically over the past 20 years no doubt reflects the severity of the underlying diseases in these high-risk patients.

Vascular surgical society of great britain and ireland: review of out-of-hours vascular procedures in a tertiary vascular unit

BACKGROUND: The aim of this study was to review out-of-hours vascular procedures in a tertiary vascular unit. METHODS: The vascular emergencies that presented outside normal working hours (17. 00 to 08.00 hours) in a vascular unit between January and June 1998 were reviewed. Only cases considered to be life or limb threatening and requiring urgent surgical or radiological intervention were assessed. RESULTS: The Table shows that a significant number of vascular emergencies was performed out of hours in one unit. This was, in part, due to an increase in the number of tertiary referrals, which represented 57 per cent of all emergency procedures. Reasons for the tertiary referrals were: no consultant vascular surgeon on call (33 per cent), no consultant interventional radiologist on call (26 per cent), lack of intensive care beds (30 per cent) and complex procedure (11 per cent). The overall mortality rate of patients referred in this period was 15 per cent. The unit has three consultant vascular surgeons, two consultant interventional radio- logists and one vascular specialist registrar. CONCLUSION: The significant increase in out-of-hours vascular emergencies, both surgical and radiological, has placed an enormous demand on senior members of the team. In addition, it has had a significant impact on the unit's elective admissions and waiting lists, in particular those for routine general surgery. To support the growth in complex emergency referrals, senior vascular fellows in both vascular surgery and radiology have been appointed and proposals are underway to restructure local vascular services.

Comparison of graded versus constant treadmill test protocols for quantifying intermittent claudication

The standard method for quantifying the symptoms of intermittent claudication is by using treadmill walking distance. It has recently been suggested that a graded exercise test is much more reproducible than a constant load exercise test. Graded protocols have also been claimed to abolish the placebo effect that has been reported with the constant load test. The reproducibility of absolute claudication distance (ACD) and initial claudication distance (ICD) using a constant load was compared to the graded load treadmill protocol. Fourteen patients (mean age 66 years) with varying severity of stable intermittent claudication were tested using a constant load (3.2 km/h, 10% gradient) and a graded load (3.2 km/h, 0% gradient increasing by 3.5% every 3 min). Patients were tested twice using each protocol in a random sequence, with a minimum 2 day interval between visits. Intra-class correlation coefficient (R) with a constant load protocol for ICD and ACD was R = 0.68, R = 0.93, respectively. With a graded protocol R = 0.84 for ICD and R = 0.98 for ACD. Relative coefficient of repeatability for ICD and ACD during constant load tests were 1.47 and 1.90 respectively and with a graded load test were 1.69 and 1.52 respectively. It was concluded that the graded load test was more reproducible than the constant load test but only by a small margin, whilst ACD was much more reproducible than ICD using either protocol.

Intrahepatic biliary cholesterol and phospholipid transport in humans: effect of obesity and cholesterol cholelithiasis

The mode of transport of biliary lipids within the hepatocyte and the role of the bile canalicular membrane (BCM) in biliary lipid secretion are not well understood. We hypothesized that biliary cholesterol and phospholipid are co-transported across the hepatocyte in vesicular form from the endoplasmic reticulum to the bile across the BCM. We obtained wedge liver biopsies and fasting gallbladder bile from 15 cholesterol gallstone patients and 10 control subjects. BCM, basolateral membrane (BLM), and many microsomal vesicular fractions were isolated by centrifugation. One of the vesicular fractions (V3) was enriched in both the microsomal and the BCM marker enzymes and had a high phosphatidylcholine proportion in its phospholipid with a fatty acid pattern similar to biliary phosphatidylcholine. Moreover, its cholesterol content was increased in the obese cholesterol gallstone subjects, who had an increase in cholesterol synthesis, as indicated by the increased activity of the HMG-CoA reductase. The cholesterol content correlated with HMG-CoA reductase activity. A direct correlation was found between cholesterol/phospholipid ratio in V3, BCM, and in bile but not in the BLM. These data are in agreement with the assumption that this vesicular fraction is involved in the transport of cholesterol and phospholipid from the endoplasmic reticulum to the site of secretion in the BCM, and thence to bile, and that this transport is enhanced in obese gallstone patients.

Prospective study of 713 below-knee amputations for ischaemia and the effect of a prostacyclin analogue on healing. Hawaii Study Group

In 51 hospitals in six European countries 713 patients requiring below-knee amputation for ischaemic disease were studied prospectively. The patients were allocated randomly to receive standard postoperative treatment or standard treatment plus intravenous infusion of the prostacyclin analogue iloprost for 6 h per day over 14-21 days. Healing of the amputation stump and the need for reamputation at a higher level were similar in the two groups. Overall at 3 months 59 per cent of stumps had healed, 19 per cent of patients had required reamputation at a higher level, 11 per cent had died and the remaining 11 per cent remained with unhealed stumps. Preoperative characteristics were analysed as possible risk factors or markers for primary healing, reamputation and death. Previous arterial reopening procedures (surgical or radiological) almost doubled the chances of primary stump healing (P < 0.05). The surgeon's assessment of the likelihood of healing was wrong in 21 per cent of cases in which the operating surgeon thought that healing would probably occur and in 52 per cent of those in which it was thought healing was improbable.

Cholesterol nucleation time measurement in nasobiliary or nasoduodenal bile. Comparison with surgical bile

The usual technique of collecting gallbladder bile at laparotomy is not suitable for sequential studies of cholesterol nucleation time (NT) in patients receiving therapy to prevent or dissolve cholesterol gallstones. Our aim was to study the feasibility of measuring NT in bile obtained by nasobiliary or nasoduodenal intubation. We studied a total of 10 cholesterol gallstone patients; in 8 bile was collected by nasobiliary drainage, in 7 it was collected by nasoduodenal intubation, and in 3 it was collected at laparotomy the next day. Three patients developed abdominal pain and increased serum amylase after endoscopic retrograde cannulation. All three biles obtained at operation nucleated quickly (NT, 1-4 days), whereas duodenal biles were all beyond the expected range (NT, > 21 days). Chymotrypsin activity, as a marker of pancreatic juice contamination, was detected in five of eight nasobiliary biles and in all seven duodenal biles but in none of the surgical biles. Free fatty acids (reflecting lipolysis) were significantly higher in duodenal than in surgical biles, with nasobiliary bile showing intermediate values. Nasobiliary bile showed either a rapid (median NT, 3 days) or a slow (median NT, 22 days) NT, depending on whether chymotrypsin activity was absent or present (p < 0.05). We conclude that duodenal bile is never suitable for NT determination because of contamination by pancreatic enzymes, and that nasobiliary bile, if not contaminated by pancreatic enzymes, may be suitable for NT determination but that its collection via a nasobiliary tube after cholecystokinin injection carries a risk of pancreatitis.

Abnormal neutrophil adhesion in sickle cell anaemia and crisis: relationship to blood rheology

Defects in neutrophil adhesion and migration may contribute to the susceptibility to infection seen in sickle cell anaemia (SCA). These dynamic defects may be influenced by abnormalities in blood rheology found in this disorder. A whole blood model was used to study neutrophil adhesion in SCA patients: neutrophil adhesion to protein coated glass was quantitated by measuring the rate of disappearance of neutrophils from heparinized whole blood circulating through a perfusion chamber. Twenty-three adult patients (Hb SS) were studied in asymptomatic steady state, of whom nine were also studied during pain crisis, both before and 4-7 d after conventional therapy. Red cell and granulocyte filterability and whole blood and plasma viscosity were also measured. The half-time for disappearance from the perfusion system (t1/2) of neutrophils from patients in the steady-state was 93.5 +/- 8.4 min, compared to 49.1 +/- 2.8 min in normal age-matched controls (P = 0.001). In crisis t1/2 was further prolonged to 170.0 +/- 16.1 min (P = 0.01 v. steady state). After therapy, t1/2 decreased to 57.0 +/- 4.5 min (P = 0.001 v. pre-therapy state and P = 0.009 v. steady state) and was comparable to Hb AA controls. These findings reveal a neutrophil adhesion defect in SCA which worsens in crisis but is corrected following supportive therapy. Red cell filterability (expressed as average resistance to flow and pore-clogging particles) and white cell filterability (expressed as pore-clogging particles) were also abnormal in SCA and were found to correlate with neutrophil adhesion. Plasma viscosity also correlated with adhesion t1/2. The defect appears to be related to abnormal blood flow properties in SCA but the rheological factors cannot fully explain either the steady-state defect or the marked changes in neutrophil adhesion during crisis.

Use of the prostacyclin analogue iloprost in the treatment of patients with critical limb ischaemia

Five large, placebo-controlled, randomised prospective multicentre trials have been completed in several European countries, including a total of 728 patients with critical limb ischaemia (CLI). 593 had ulceration or gangrene and it is these which will be analysed in detail. Only patients with CLI who were unsuitable for further reopening procedures were entered and approximately a third of the patients had already had attempts at surgical revascularisation or interventional radiology. The maximum tolerated dose up to 2 ng/kg/min was determined during the first three days and then continued as a six-hourly intravenous infusion every day for two to four weeks, depending on the study. Pooled results showed a significant overall 21% increase in ulcer healing rate due to iloprost (p less than 0.001) compared with placebo. The improvement was greater in the three studies when treatment was continued for four weeks. The very hard end point of a major amputation or death during a 3 to 6 month follow up was available in three of the studies. Analysis of these together demonstrated a significantly lower incidence of major amputations after iloprost treatment (p less than 0.05). Thus the existing weight of evidence from a large number of patients suggests that a course of intravenous iloprost is useful in the management of patients with CLI and trophic skin changes, who are unsuitable for reconstructive surgery or catheter procedures.

[Correlation between the results of Doppler velocimetry with spectral analysis and the viscosity of cord blood]

The contribution of rheological factors to be impedance of blood flow in the umbilical artery as determined by continuous wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55 p. cent of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placenta arterioles are a more important determinant of umbilical artery impedance.