Surrogate markers in clinical trials—Challenges and opportunities

Initial Reduction in Ulcer Size As a Prognostic Indicator for Complete Wound Healing: A Systematic Review of Diabetic Foot and Venous Leg Ulcers

Significance: Percent area reduction (PAR) is commonly reported in trials including diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs). It is unclear how well PAR performs as a surrogate marker for complete wound closure. This review aimed to summarize all available evidence evaluating PAR as a predictor of complete DFU and VLU healing. Recent Advances: A review searching the CENTRAL, MEDLINE, EMBASE, and EMCARE databases was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Randomized-controlled trials and observational studies reporting PAR and any measure of its predictive ability were included. Outcomes included performance measures of PAR, timing of PAR, outcome measurement, and specific PAR cutoffs. Critical Issues: Meta-analysis was not possible due to high variability in wound duration at study start (2-48 weeks), PAR timing (2-8 weeks), PAR cutoff (-3% to 90%; determined post hoc in most studies), and outcome assessment (10-24 weeks). Six studies (21,430 DFU patients) report PAR as having acceptable to outstanding discriminatory ability (C-statistic 0.720-0.910). Five studies (29,775 VLU patients) report PAR as having poor to excellent discriminatory ability (C-statistic 0.680-0.830). One study (241 DFU and VLU patients) reports PAR sensitivity and specificity of 58.5% and 90.5%, respectively. All studies were determined to have high risk of bias. Future Directions: Despite promising discriminatory ability, most studies report post hoc analysis of patients in randomized trials, are highly heterogenous in study design, and have high risk of bias. There is scant evidence to support PAR in isolation as a surrogate for complete DFU or VLU healing in routine clinical practice.

Pulsed electric field increases the extraction yield of extra virgin olive oil without loss of its biological properties

INTRODUCTION

Pulsed electric field (PEF) has been used for improving extraction of extra virgin olive oil (EVOO). However, the biological changes induced by the consumption of pulsed electric field-obtained extra virgin olive oil (PEFEVOO) have not been studied yet.

MATERIALS AND METHODS

EVOO oils from Empeltre variety were prepared by standard (STD) cold pressure method involving crushing of the olives, malaxation and decanting and by this procedure including an additional step of PEF treatment. Chemical analyses of EVOO oils were done. Male and female Apoe-deficient mice received diets differing in both EVOOs for 12 weeks, and their plasma, aortas and livers were analyzed.

RESULTS

PEF application resulted in a 17% increase in the oil yield and minimal changes in chemical composition regarding phytosterols, phenolic compounds and microRNA. Only in females mice consuming PEF EVOO, a decreased plasma total cholesterol was observed, without significant changes in atherosclerosis and liver steatosis.

CONCLUSION

PEF technology applied to EVOO extraction maintains the EVOO quality and improves the oil yield. The equivalent biological effects in atherosclerosis and fatty liver disease of PEF-obtained EVOO further support its safe use as a food.

Endpoints: types, selection, interpretation of the results obtained on the example of cardiology studies

The importance of high-quality randomized controlled trials cannot be overemphasized. Each such study attempts to answer a specific clinical question. To do this, it is necessary to determine in advance the indicator of achievement of a specific result for a certain period of time. This indicator is the endpoint (EP) of the study, i.e. one or another outcome of the disease or a change in the laboratory and functional characteristics. Its choice directly affects the intended design and sample size of the study. The article provides a classification and hierarchy of EPs (depending on the purpose), describes the features and limitations of the use of important clinical outcomes and surrogate indicators. The reasons why composite EPs are widely used in cardiology studies are described. Special attention should be paid to EP interpretation within secondary analysis, a positive result of which can only be assessed if a treatment effect is demonstrated in terms of the primary indicator of efficacy or safety. The current review is supplemented by clinical examples of cardiology studies.

Genetic Determinants of Visit-to-Visit Lipid Variability: Genome-Wide Association Study in Statin-Naïve Korean Population

Background and Aim

There is a growing evidence that fluctuation in lipid profiles is important in cardiovascular outcomes. We aimed to identify single nucleotide polymorphism (SNP) variants associated with low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C) variability in statin-naïve Korean subjects and evaluate their associations with coronary atherosclerosis.

Methods

In statin-naïve subjects from Gene-Environment of Interaction and phenotype cohort, we performed genome-wide association studies of lipid variability; the discovery (first) and replication (second) sets included 4,287 and 1,086 subjects, respectively. Coronary artery calcium (CAC) score and degree of coronary artery stenosis were used as outcome measures. Cholesterol variability was determined by standard deviation and average successive variability, and significant coronary atherosclerosis was defined as CAC score ≥400 or coronary stenosis ≥70%.

Results

Mean HDL-C and LDL-C level were 54 ± 12 and 123 ± 30 mg/dL in the first set and 53 ± 12 and 126 ± 29 mg/dL in the second set. APOA5 rs662799 and APOA5 rs2266788 were associated with LDL-C variability and PXDNL rs80056520, ALDH2 rs671, HECTD4 rs2074356, and CETP rs2303790 were SNPs associated for HDL-C variability. APOA5 rs662799 passed Bonferroni correction with p-value of 1.789 × 10⁻⁹. Among the SNPs associated with cholesterol variability, rs80056520 and rs2266788 variants were associated with CACS ≥400 and coronary stenosis ≥70% and rs662799 variant was associated with coronary stenosis ≥70%.

Conclusion

Two SNPs associated with LDL-C variability (APOA5 rs662799 and rs2266788) and one SNP associated with HDL-C variability (PXDNL rs80056520) were significantly associated with advanced coronary artery stenosis. Combining GWAS results with imaging parameters, our study may provide a deeper understanding of underlying pathogenic basis of the link between lipid variability and coronary atherosclerosis.

Association of Circulating Cathepsin S and Cardiovascular Disease Among Patients With Type 2 Diabetes: A Cross-Sectional Community-Based Study

BACKGROUND

Cathepsin S, as an adipokine, was reported to play a critical role in various disease, including atherosclerosis and diabetes. The present study aims to elucidate the relationship between circulating cathepsin S and cardiovascular disease (CVD) in patients with type 2 diabetes.

METHODS

A total of 339 type 2 diabetes individuals were enrolled in this cross-sectional community-based study. Basic information, medical and laboratory data were collected. Serum cathepsin S levels were assessed by ELISA.

RESULTS

Compared to the CVD (-) group, levels of serum cathepsin S were significantly higher in the CVD (+) group, with the median 23.68 ng/ml (18.54-28.02) and 26.81 ng/ml (21.19-37.69) respectively (P < 0.001). Moreover, patients with acute coronary syndrome (ACS) had substantially higher levels of serum cathepsin S than those with stable angina pectoris (SAP), with the median 34.65 ng/ml (24.33-42.83) and 25.52 ng/ml (20.53-31.47) respectively (P < 0.01). The spearman correlation analysis showed that circulating cathepsin S was correlated with several cardiovascular risk factors. The univariate and multivariate logistic regression analysis revealed that circulating cathepsin S was an independent risk factor for CVD (all P < 0.001) after adjustment for potential confounders. Restricted cubic spline analysis showed circulating cathepsin S had a linearity association with CVD. In addition, receiver operating characteristic (ROC) curve analysis demonstrated that the area under curve (AUC) values of cathepsin S was 0.80 (95% CI: 0.75-0.84, P < 0.001), with the optimal cutoff value of cathepsin 26.28 ng/ml.

CONCLUSION

Circulating cathepsin S was significantly higher in the CVD (+) group than that in the CVD (-) one among type 2 diabetes. The increased serum cathepsin S levels were associated with increased risks of CVD, even after adjusting for potential confounders. Thus, cathepsin S might be a potential diagnostic biomarker for CVD.

Subclinical atherosclerosis and associated risk factors among HIV-infected adults in Jos, North Central Nigeria: a cross-sectional study

Introduction

human immunodeficiency virus (HIV) is evolving into a leading cause of cardiovascular diseases (CVD) in sub-Saharan Africa (SSA) where the burden of HIV remains high. Atherosclerosis underlie progression to CVD. We therefore examined the prevalence of subclinical atherosclerosis and its association with traditional and non-traditional risk factors for CVD in Nigerian HIV-infected adults.

Methods

this was a cross-sectional study involving randomly selected stable HIV-infected patients with undetectable viral load attending HIV clinics at the Jos University Teaching Hospital and Faith Alive Foundation in Jos, Nigeria. Demographic data, biophysical measurements, cardiovascular risk factors and information regarding HIV-related factors, fasting serum lipid profile, fasting plasma glucose, high-sensitivity C-reactive protein and Carotid-Intima-Media-Thickness (CIMT) were assessed. Subclinical atherosclerosis was defined using a cut-off value of mean CIMT ≥ 0.78 mm. Data were analyzed with the Statistical Package for Social Sciences® (SPSS) software version 23.0 (IBM Corp., Chicago, Illinois, USA). Bivariate analysis and multivariate logistic regression were used to examine the association between risk factors of CVD and subclinical atherosclerosis. The statistical significance level was set at p ≤ 0.05.

Results

a total of 148 HIV adults (70.9% being females) on Anti-Retroviral Therapy (ART) were included in this study. The prevalence of subclinical atherosclerosis was 7.4%. Among subjects with subclinical atherosclerosis (SCA), 63.6% were males and 81.8% were hypertensive. Elevated blood glucose, lipids and high-sensitivity C-reactive protein, body mass index (BMI), HIV-related parameters (duration of HIV infection, antiretroviral regimen, CD4+ cell count), current smoking status, alcohol use, were not significantly associated with subclinical atherosclerosis (p>0.05). Male gender [OR(95%CI=4.91(1.36-17.77)], age [OR(95%CI)=1.14(1.06-1.23)], hypertension [OR(95%CI=14.4(3.03-71.86)] and metabolic syndrome [OR(95%CI=8.34(1.73-40.18)] were significantly associated with SCA at bivariate analysis. After adjusting for age, sex and antiretroviral regimen, only increasing age [Adjusted Odds Ratio (AOR) (95% confidence interval (CI)] = 1.12(1.01-1.25)] and hypertension [AOR (95%CI)=10.67 (1.31-87.18)], remained as independent predictors of subclinical atherosclerosis (SCA).

Conclusion

the prevalence of subclinical atherosclerosis among HIV-infected adults is high in Nigeria. It is significantly associated with increasing age and hypertension. Traditional CVD risk factors such as dyslipidaemia, diabetes mellitus and obesity were not associated with subclinical atherosclerosis in this population.

Clinical evidence on dietary supplementation with chia seed (Salvia hispanica L.): a systematic review and meta-analysis

Context

Chia seed is a popular dietary supplement, taken mainly for its high content of alpha-linolenic acid, vegetable protein, and dietary fiber, yet information about its clinical effects is lacking.

Objective

This review aims to summarize the clinical evidence regarding the use of chia seed for a wide variety of health conditions.

Data Sources

A number of databases, including PubMed and Embase, were searched systematically.

Study Selection

Randomized controlled trials that assessed the clinical effects of chia seed consumption in human participants were included. The quality of trials was assessed using the Cochrane Risk of Bias Tool.

Data Extraction

Data on study design, blinding status, characteristics of participants, chia seed intervention, comparator, clinical assessment, duration of intake, interval of assessment, and study funding status were extracted. Meta-analysis was performed.

Results

Twelve trials were included. Participants included healthy persons, athletes, diabetic patients, and individuals with metabolic syndrome. Pooling of results showed no significant differences except for the following findings of subgroup analysis at higher doses of chia seed: (1) lower postprandial blood glucose level (mean difference [MD] of -33.95 incremental area under the curve [iAUC] [mmol/L × 2 h] [95%CI, -61.85, -6.05] and -51.60 iAUC [mmol/L × 2 h] [95%CI, -79.64, -23.56] at medium doses and high doses, respectively); (2) lower high-density lipoprotein in serum (MD of -0.10 mmol/L [95%CI, -0.20, -0.01]); and (3) lower diastolic blood pressure (MD of -7.14 mmHg [95%CI, -11.08, -3.19]). The quality of all evidence assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was low or very low. All trials employed only surrogate markers as outcomes.

Conclusions

Future trials with improved methodological quality, well-described clinical events, and validated surrogate markers as outcomes are needed to support the potential health benefits of chia seed consumption.

Systematic Review Registration

PROSPERO registration no. CRD42015029990.

The Clinical Significance and Application of Vascular Stiffness Measurements

Increasing evidence points out at vascular stiffness (and in particular aortic stiffness measured by pulse wave velocity) as a reliable biomarker of vascular aging, able to integrate in a single measure the overall burden of cardiovascular (CV) risk factors on the vasculature over time; furthermore, it may be per se a mechanism of disease, by inducing microcirculatory damage and favoring CV events. Increased aortic stiffness has been shown to predict future CV events and improve risk reclassification in those at intermediate risk. However, several questions in this field are still open, limiting the wide use of these tools in the clinical practice. This article will review the basic aspects of physiology of large artery stiffness, as well as current evidence about its possible clinical applications.

Bone Marrow Mononuclear Cells Transfer for Patients after ST-Elevated Myocardial Infarction: A Meta-Analysis of Randomized Control Trials

PURPOSE

Results on the clinical utility of cell therapy for ST-elevated myocardial infarction (STEMI) are controversial. This study sought to analyze the efficacy of treatment with intracoronary bone marrow mononuclear cells (BMMC) on left ventricular (LV) function and remodeling and LV diastolic and systolic function in patients with STEMI.

MATERIALS AND METHODS

Literature search of PubMed and EMBASE databases between 2004 and 2017 was performed for randomized controlled trials in STEMI patients who underwent successful percutaneous coronary intervention and received intracoronary BMMC therapy. The defined end points were left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV). Also, sensitivity analysis and several subgroup analyses based on follow-up duration, timing of injection, doses of cells, and imaging modalities were conducted to strengthen the statistic power of the study.

RESULTS

A total of 22 trials with 1360 patients were available for the current meta-analysis. The pooled statistics showed a significant improvement in LVEF {2.58 [95% confidence interval (CI), 1.32, 3.84]; p<0.001}, LVEDV [-3.73, (95% CI, -6.94, -0.52), p=0.02], and LVESV [?4.67, (95% CI, -7.07, -2.28), p<0.001] in the BMMC group, compared with the control group. However, in sensitivity analysis, a significant reduction in LVEDV disappeared, while the outcomes of LVEF and LVESV remained unchanged. The same results were presented in the subgroup analysis adjusting for imaging modalities and timing of cells injection.

CONCLUSION

BMMC transplantation in patients with STEMI was found to lead to improvement in LVEF, LVEDV, and LVESV parameters, indicating that cell therapy has a potential beneficial effect on LV remodeling and function.

Carotid Intima-Media Thickness as a Cardiovascular Risk Factor and Imaging Pathway of Atherosclerosis

Assessment of carotid intima-media thickness (IMT) has emerged as a simple and noninvasive technique for measuring atherosclerotic burden. Although serum biomarkers have been linked to the risk of developing atherosclerosis, carotid IMT has the theoretical advantage of directly visualizing a final consequence of the disease itself, namely atherosclerosis in the vessel wall. The current widespread application of carotid IMT measurements has been based on the validity, standardization, and reproducibility of the measurement and the evidence that an increased carotid IMT can be regarded as an attractive biomarker of atherosclerosis and of increased cardiovascular risk, potentially useful as a therapeutic target in those at increased cardiovascular risk. The utilization of carotid IMT measurements as a surrogate end point in clinical trials evaluating a specific drug intervention may result in considerably smaller efforts and costs than when using a hard end point such as myocardial infarction, stroke, or death. In addition, the use of carotid IMT measurement as a screening tool in clinical practice in association with traditional risk factors may improve risk classification and decisions regarding therapeutic interventions. However, although carotid IMT may be correlated with clinical outcomes, changes in surrogate end points over time that result from a particular therapy may not necessarily be predictive of future cardiovascular events. Therefore, it is necessary to perform more clinical studies to clearly define the relationship between the modifications in carotid IMT and the changes in cardiovascular events. In an era of economic burden, when there is a clear combination of limited resources with high expense of innovation in drug development, carotid IMT represents a reasonable, worthwhile surrogate trial end point with a history of nearly 30 years of technical progress and clinical research. Current data strongly suggest that carotid IMT will continue to successfully be used as a valuable tool in clinical atherosclerosis research.

Doing it hard in the bush: Aligning what gets measured with what matters

What gets measured gets managed. Funding of health services is substantially determined by operational activity and specific outcome indicators. In day-to-day clinical decision-making, surrogate markers, such as glycosylated haemoglobin and blood pressure, are commonly used to modify risks of 'hard' outcomes that include kidney failure, ischaemic cardiac events, stroke and all-cause mortality. In many settings, surrogates are all we have to go on. As a consequence, current health funding models heavily rely on surrogate-based key performance indicators [KPIs]. While surrogates are convenient and provide immediate information, there is an obligation to ensure that they are appropriate, reliable and validated in context. In contrast, hard outcomes, the real consequences of illness, are usually realised over an extended timeframe. Additionally, and for a host of reasons, hard endpoints have the greatest social, emotional and economic impact for people at the far end of the health system; those in rural and remote settings - 'in the bush' - especially Indigenous Australians. We propose a health service assessment approach that aligns short-term decision-making with patient-centred and longer term hard outcomes, one that takes into account community, cultural and environmental factors, especially remoteness. Communities should have a major say in determining what health indicators are measured and managed.

Use of Surrogate Outcomes in Nephrology Research

Clinical trials are large and expensive and could require exceedingly long-term follow-up for subjects to reach clinically meaningful end points. To combat these methodologic issues, researchers sometimes use biomarkers as surrogate end points. A biomarker is an objectively measured characteristic that is indicative of some underlying phenomenon or process, while a surrogate is a biomarker that "takes the place" of a clinically meaningful outcome, usually earlier in the disease process. This paper reviews the history, strengths, and weaknesses of surrogate outcome use in clinical research and then discusses potential surrogate outcomes in nephrology research.

High serum Aspartate transaminase levels on day 3 postliver transplantation correlates with graft and patient survival and would be a valid surrogate for outcome in liver transplantation clinical trials

Aspartate transaminase, a liver specific enzyme released into serum following acute liver injury, is used in experimental organ preservation studies as a measure of liver IR injury. Whether post-operative serum transaminases are a good indicator of IR injury and subsequent graft and patient survival in human liver transplantation remains controversial. A single centre prospectively collected liver transplant database was analysed for the period 1988-2012. All patients were followed up for 5 years or until graft failure. Transaminase levels on the 1st, 3rd and 7th post-operative days were correlated with the patient demographics, operative outcomes, post-operative complications and both graft and patient survival via a binary logistic regression analysis. Graft and patient survival at 3 months was 80.3% and 87.5%. AST levels on the 3rd (P = 0.005) and 7th (P = 0.001) post-operative days correlated with early graft loss. Patients were grouped by their AST level (day 3): <107iU, 107-1213iU, 1213-2744iU and >2744iU. The incidence of graft loss at 3 months was 10%, 12%. 27% and 59% and 1-year patient mortality was 12%, 14%, 27% and 62%. Day 3 AST levels correlate with patient and graft outcome post-liver transplantation and would be a suitable surrogate endpoint for clinical trials in liver transplantation.

Improvement in non-alcoholic fatty liver disease severity is associated with a reduction in carotid intima-media thickness progression

BACKGROUND AND AIMS

n-3 polyunsaturated fatty acid (PUFA) treatment may decrease liver fat in non-alcoholic fatty liver disease (NAFLD), but uncertainty exists whether this treatment also decreases cardiovascular disease (CVD) risk in NAFLD. We tested whether 15-18 months n-3 PUFA [docosahexaenoic acid (DHA) and eicosapentaenoic acid] (Omacor/Lovaza, 4 g/day) vs placebo decreased carotid intima-media thickness (CIMT) progression, a surrogate marker of CVD risk. We also evaluated if improvement in markers of NAFLD severity was associated with decreased CIMT progression over time.

METHODS

In a pre-specified sub-study of the WELCOME (Wessex Evaluation of fatty Liver and Cardiovascular markers in NAFLD with OMacor thErapy) trial (NCT00760513), CIMT was measured using B-mode ultrasound while NAFLD severity was assessed by measuring liver fat percentage (magnetic resonance spectroscopy) and hepatic necro-inflammation (serum cytokeratin-18 (CK-18) concentration), at baseline and end of study.

RESULTS

92 patients (age 51.5 ± 10.7 years, 57.6% men) completed the study. In the treatment group (n = 45), CIMT progressed by 0.012 mm (IQR 0.005-0.020 mm) compared to 0.015 mm (IQR 0.007-0.025 mm) in the placebo group (n = 47) (p = 0.17). Reduced CIMT progression in the entire cohort was independently associated with decreased liver fat (standardized β-coefficient 0.32, p = 0.005), reduced CK-18 levels (standardized β-coefficient 0.22, p = 0.04) and antihypertensive usage (standardized β-coefficient -0.31, p = 0.009) in multivariable regression analysis after adjusting for all potential confounders. Decreased weight (standardized β-coefficient 0.30, p < 0.001) and increased DHA tissue enrichment during the 18-month study (standardized β-coefficient -0.19, p = 0.027) were both independently associated with decreased liver fat, but not with CK-18.

CONCLUSION

Improvement in two markers of NAFLD severity is independently associated with reduced CIMT progression.

Carotid Intima Media Thickness in Mainly Female HIV-Infected Subjects in Rural South Africa: Association With Cardiovascular but Not HIV-Related Factors

BACKGROUND

In sub-Saharan Africa, the number of persons living with human immunodeficiency virus (HIV) has increased immensely. In parallel, rates of noncommunicable diseases, especially cardiovascular disease, are rising rapidly in resource-limited settings. This study aims to evaluate the relation between subclinical atherosclerosis and HIV-related and traditional cardiovascular risk factors in HIV-infected patients in rural South Africa.

METHODS

A cross-sectional study was performed among HIV-infected patients visiting a health center in Limpopo, South Africa. Demographic and HIV-related information was collected, and cardiovascular risk was assessed. Carotid intima media thickness (CIMT) was measured and the prevalence of subclinical atherosclerosis (CIMT >0.78 mm) was calculated. The association between cardiovascular or HIV-related determinants with CIMT was analyzed using linear and logistic regression models adjusted for age and sex.

RESULTS

The median CIMT in 866 subjects (median age [interquartile range], 41 [35-48] years; 69% female) was 0.589 mm (interquartile range, 0.524-0.678 mm), and values seemed higher than in healthy Western reference populations. In fact 12% of subjects (106 of 866) had subclinical atherosclerosis. Hypertension, high body mass index, previous cardiovascular event, diabetes mellitus, total and low-density lipoprotein cholesterol, estimated glomerular filtration rate, metabolic syndrome, and the Framingham Heart Risk score were independently associated with CIMT. No HIV-related determinants were associated with CIMT.

CONCLUSIONS

In a predominantly female HIV-infected population in South Africa, CIMT values are considerably high and associated with cardiovascular risk factors, rather than HIV-related factors. This finding emphasizes the need to screen for cardiovascular disease among persons with HIV infection in resource-limited settings. Ideally, this screening would be integrated into care for chronic HIV infection, posing a major challenge for the future.

Secondary prevention of new vascular events with lifestyle intervention in patients with noncardioembolic mild ischemic stroke: a single-center randomized controlled trial

BACKGROUND

Lifestyle modification is associated with a substantially decreased risk of cardiovascular events. However, the role of lifestyle intervention for secondary prevention in patients with noncardioembolic ischemic stroke is inadequately defined. We assessed the hypothesis that lifestyle intervention can reduce the onset of new vascular events in patients with noncardioembolic mild ischemic stroke.

METHODS

We conducted an observer-blind randomized controlled trial that enrolled 70 patients (48 men, mean age 63.5 years) with acute noncardioembolic mild ischemic stroke. The patients were allocated in equal numbers to a lifestyle intervention group or a control group. We performed lifestyle interventions, which comprised exercise training, salt restriction and nutrition advice for 24 weeks. Then all patients were prospectively followed up for occurrence of the primary endpoints, including hospitalization due to stroke recurrence and the onset of other vascular events. We also evaluated systolic blood pressure (SBP) at the clinic and at home, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), hemoglobin A1c (HbA1c) and high-sensitivity C-reactive protein (hs-CRP) to compare the efficacy of the lifestyle interventions.

RESULTS

This trial was terminated earlier than expected because of the prespecified early stopping rule for efficacy. After the 24-week intervention period, the intervention group showed a significant increase in daily physical activity and a significant decrease in salt intake (physical activity, p = 0.012; salt intake, p < 0.001), with a significant difference between the randomized groups (physical activity, p < 0.001; salt intake, p = 0.018). Similarly, blood pressure was decreased and the HDL-C levels were increased in the intervention group (SBP, p < 0.001; HDL-C, p = 0.018), with significant differences between the randomized groups (SBP, p < 0.001; HDL-C, p = 0.022). In contrast, LDL-C, HbA1c and hs-CRP tended to decrease in the intervention group, but this decrease did not achieve significance. After a median follow-up period of 2.9 years, 12 patients allocated to the control group and 1 patient in the lifestyle intervention group experienced at least 1 vascular event. A sequential plans analysis indicated the superiority of the lifestyle intervention in interim analysis. Kaplan-Meier survival curves after the log-rank test showed a significant prognostic difference between the randomized groups (p = 0.005).

CONCLUSIONS

Lifestyle intervention with appropriate medication is beneficial for reducing the incidence of new vascular events and improving vascular risk factors in patients with noncardioembolic mild ischemic stroke.

Carotid intima-media thickness studies: study design and data analysis

BACKGROUND

Carotid intima-media thickness (CIMT) measurements have been widely used as primary endpoint in studies into the effects of new interventions as alternative for cardiovascular morbidity and mortality. There are no accepted standards on the use of CIMT measurements in intervention studies and choices in the design and analysis of a CIMT study are generally based on experience and expert opinion. In the present review, we provide an overview of the current evidence on several aspects in the design and analysis of a CIMT study on the early effects of new interventions.

SUMMARY OF ISSUES

A balanced evaluation of the carotid segments, carotid walls, and image view to be used as CIMT study endpoint; the reading method (manual or semi-automated and continuously or in batch) to be employed, the required sample size, and the frequency of ultrasound examinations is provided. We also discuss the preferred methods to analyse longitudinal CIMT data and address the possible impact of, and methods to deal with missing and biologically implausible CIMT values.

CONCLUSIONS

Linear mixed effects models are the preferred way to analyse CIMT data and do appropriately handle missing and biologically implausible CIMT values. Furthermore, we recommend to use extensive CIMT designs that measure CIMT at regular points during the multiple carotid sites as such approach is likely to increase the success rates of CIMT intervention studies designed to evaluate the effects of new interventions on atherosclerotic burden.

Circulating cathepsin K as a potential novel biomarker of coronary artery disease

BACKGROUND

Cathepsin K (CatK) is one of the most potent mammalian collagenases involved in atherosclerosis-based vascular disease. We investigated whether circulating CatK is associated with the prevalence of coronary artery disease (CAD).

METHODS

Two-hundred fifty-two consecutive subjects were enrolled from among patients who underwent coronary angiography and intravascular ultrasound analyses. One-hundred thirty-two age-matched subjects served as controls. Plasma CatK, intact procollagen type I N-terminal propeptide (I-PINP), and linked carboxy-terminal telopeptide of collagen type I (ICTP) were measured.

RESULTS

Patients with CAD had higher CatK levels (44.0 ± 31.2 versus 15.5 ± 8.3 ng/mL, P < 0.001) and ICTP/I-PINP ratios (0.2 ± 0.1 versus 0.04 ± 0.03, P < 0.001) than the controls. Patients with acute coronary syndrome had higher CatK levels than those with stable angina pectoris. Overall, linear regression analysis showed that the CatK levels correlated positively with ICTP/I-PINP ratios (r = 0.41, P < 0.001). Multiple logistic regression analysis showed that CatK levels were independent predictors of CAD (odds ratio, 1.15; 95% CI, 1.07 to 1.23; P < 0.01). Furthermore, CatK levels were also correlated positively with percent plaque volumes and inversely with percent fibrous volumes by intravascular ultrasound.

CONCLUSIONS

These data indicated that high levels of CatK are closely linked with the presence of CAD and that CatK serves as a novel biomarker for CAD.

Lessons from the past and promises for the future for carotid intima-media thickness

Carotid intima-media thickness (CIMT) measurements have been used in cardiovascular research for more than 2 decades. There is a wealth of evidence showing that CIMT can be assessed in a reproducible manner and that increased CIMT relates to unfavorable risk factor levels and atherosclerosis elsewhere in the arterial system and to the risk of vascular events. Change in CIMT over time can be readily assessed, and trials showed that the rate of change is modifiable by treatment. Several issues important for the cardiovascular research community and its application in clinical practice are still outstanding. Promising future areas for CIMT measurements are: 1) application in studies among children and adolescents; 2) use of CIMT trials positioned decisively before the start of a morbidity and mortality trial; and 3) the use of CIMT measurement in risk stratification in those with an intermediate 10-year risk estimate.

Clinical trial design in the neurocritical care unit

Clinical trials provide a robust mechanism to advance science and change clinical practice across the widest possible spectrum. Fundamental in the Neurocritical Care Society's mission is to promote Quality Patient Care by identifying and implementing best medical practices for acute neurological disorders that are consistent with the current scientific knowledge. The next logical step will be to foster rapid growth of our scientific body of evidence, to establish and disseminate these best practices. In this manuscript, five invited experts were impaneled to address questions, identified by the conference organizing committee as fundamental issues for the design of clinical trials in the neurological intensive care unit setting.

C-reactive protein, statins and the risk of vascular events: a better understanding

The association between C-reactive protein (CRP) and cardiovascular disease has been under investigation for more than sixty years. Lately, findings from the Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) trial opened a new frontier: that of prescribing statins for vascular events risk reduction based upon the baseline CRP levels in otherwise healthy adults. Although the results from the JUPITER were impressive, ambiguities and arguments about this association have remained. Moreover, the results of a report by Heart Protection Study investigators have added to the complexities of the correlation between CRP levels and the risk of vascular events. In this review, a summary of the structural and functional properties of CRP and findings from various randomized controlled trials and observational studies is provided. This may lead to a better understanding of the intricate link between CRP levels and the risk of ensuing vascular events and the intermediary role of statins in reducing the vascular risk beyond what is justified by the lipocentric theory, by reducing the levels of CRP.

Algorithms to measure carotid intima-media thickness in trials: a comparison of reproducibility, rate of progression and treatment effect

BACKGROUND

Current ultrasound protocols to measure carotid intima-media thickness (CIMT) in trials differ considerably. The best CIMT protocol would be one that combines high reproducibility, a large and precise estimate of the rate of CIMT progression and a large and precise estimate of the treatment effect. We performed a post-hoc analysis to determine the best algorithm for determining CIMT using data from the METEOR study, a randomized double-blind, placebo-controlled study of the effect of rosuvastatin on CIMT progression in 984 low coronary heart disease risk individuals with increased CIMT.

METHODS

CIMT information was collected from two walls (near and far wall), three segments (common carotid, bifurcation and internal carotid artery), five different angles (for the right carotid artery - 60, 90, 120, 150, and 180 degrees on the Meijer's carotid arc; for the left - 300, 270, 240, 210, and 180 degrees) of two sides (left and right carotid artery), resulting in possibly (2 × 3 × 5 × 2 =) 60 measurements. On the basis of combinations of these measurements, we built 66 different ultrasound protocols to estimate a CIMT for each individual (22 protocols for mean common CIMT, 44 protocols for mean maximum CIMT). For each protocol we assessed reproducibility [intraclass correlation (ICC), mean difference of duplicate scans], 2-year progression rate in the placebo group with its corresponding standard error and treatment effect (difference in CIMT progression between rosuvastatin and placebo) and its corresponding standard error.

RESULTS

Data of duplicate ultrasound examinations at baseline and end of study were available for 688 participants (70% of 984). The ICC based on duplicate baseline examinations ranged from 0.81 to 0.95. CIMT progression rates in the placebo group ranged from 0.0046 to 0.0177 mm/year, with SE ranging from 0.00134 to 0.00337. Treatment effects ranged from 0.0141 to 0.0388 mm/year. The protocols with highest reproducibility, highest CIMT progression/precision ratio and highest treatment effect/precision ratio were those measuring both near and far wall for at least two angles.

CONCLUSION

Ultrasound protocols that include CIMT measurements at multiple angles of both near and far wall give the best balance between reproducibility, rate of CIMT progression, treatment effect and their associated precision in this low-risk population with subclinical atherosclerosis.

Prevalence and risk factors of carotid vessel wall inflammation in coronary artery disease patients: FDG-PET and CT imaging study

OBJECTIVES

We investigated the prevalence and clinical risk factors of carotid vessel wall inflammation by means of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in a population consisting of coronary artery disease (CAD) patients.

BACKGROUND

The atherosclerotic disease process is characterized by infiltration and retention of oxidized lipids in the artery wall, triggering a disproportionate inflammatory response. Efforts have been made to use noninvasive imaging to quantify this inflammatory response in the vessel wall. Recently, carotid FDG-PET has been shown to reflect the metabolic rate of glucose, a process known to be enhanced in inflamed tissue.

METHODS

Carotid inflammation was quantified in 82 CAD patients (age 62 ± 10 years) as the maximum target-to-background ratio ((wholevessel)TBR(max)). Furthermore, we assessed the maximal standardized uptake value values ((wholevessel)SUV(max)), the single hottest segment (SHS), and the percent active segments (PAS) of the FDG uptake in the artery wall, measured by FDG-PET.

RESULTS

Whole-vessel TBR(max) >1.8 was present in 67%, >2.0 in 39%, >2.2 in 23%, and >2.4 in 12% of the population. Multiple linear regression analysis with backward elimination revealed that body mass index (BMI) ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.01), smoking (p = 0.02), and hypertension (p = 0.01) were associated with (wholevessel)TBR(max). The number of components of the metabolic syndrome was also associated with (wholevessel)TBR(max) (p = 0.02). In similar analyses, (wholevessel)SUV(max) was associated with BMI ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.004), male gender (p = 0.02), and hypertension (p = 0.04); SHS with BMI ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.02), smoking (p = 0.04), and hypertension (p = 0.05); PAS with BMI ≥30 kg/m2 (p = 0.001), smoking (p = 0.03), and hypertension (p = 0.01).

CONCLUSIONS

Carotid inflammation as revealed by FDG-PET is highly prevalent in the CAD population and is associated with obesity, age over 65 years, history of hypertension, smoking, and male gender. Artery wall FDG uptake increased when components of the metabolic syndrome clustered.

Surrogate end points in secondary analyses of cardiovascular trials

A surrogate end point is one that is used as a substitute for a clinical end point of more direct interest, usually for reasons of practicality, and that is expected to predict clinical benefit. Surrogate end points play a critical role in the advancement of all medical research, and cardiovascular (CV) research in particular. However, the relationship between a surrogate end point and its clinical end point is usually complex, and there are many examples where results based on surrogates have proved to be misleading. Secondary analyses of existing clinical trial data are likely to involve surrogate end points, if only because clinical end points will have been extensively studied as part of the primary analysis of a trial large enough to collect useful clinical end point data. Validation of a surrogate end point is a laudable goal for a secondary analysis of a large clinical end point trial (or meta-analysis of multiple smaller trials), and the result may be an important new tool for further study of a class of compounds in a particular disease context. Secondary analyses using surrogate end points may also provide new insight into disease or treatment mechanism, but as with any surrogate end point analysis, the results can mislead, and the existing literature is heavy on application and light on methodology. Surrogate end points often substitute efficiency for clarity, and while many interesting and potentially informative secondary analyses of CV trials will involve surrogates, results are likely to be ambiguous and should be interpreted with care.

Effects of telmisartan and losartan on cardiovascular protection in Japanese hypertensive patients

The Telmisartan and Losartan Cardiac Evaluation Trial, a multicenter, prospective, randomized, open-labeled, blinded-endpoint trial, was designed to compare the effects of two angiotensin II receptor blockers (ARBs), telmisartan and losartan, on cardiovascular protection in Japanese patients with mild to moderate essential hypertension. We compared the effects of telmisartan and losartan on left ventricular (LV) hypertrophy, cardiac function, atherosclerosis of carotid arteries and surrogate markers related to the actions of peroxisome proliferator-activated receptor-γ. A total of 58 patients were enrolled in the present trial and the follow-up period was 1 year. There were no significant differences in blood pressure (BP) levels between the telmisartan group and the losartan group throughout the trial. The percentage of the patients treated with ARB monotherapy was significantly higher in the telmisartan group compared with the losartan group. In addition, the progression of intima-media thickness of common carotid artery was significantly inhibited in the telmisartan group compared with the losartan group. Neither group experienced significant changes in cardiac function and LV mass index. There were no differences between the groups with respect to changes in surrogate markers such as serum adiponectin, creatinine, homeostasis model assessment index, plasminogen activator inhibitor-1 and high sensitivity C-reactive protein. Although BP levels were equal and well controlled in both groups, telmisartan showed more protective vascular effects than losartan.

A preclinical algorithm of soluble surrogate biomarkers that correlate with therapeutic inhibition of the MET oncogene in gastric tumors

The MET oncogene is amplified in a fraction of human gastric carcinoma cell lines, with consequent overexpression and constitutive activation of the corresponding protein product, the Met tyrosine kinase receptor. This genetically driven hyperactivation of Met is necessary for cancer cell growth and survival, so that Met pharmacological blockade results in cell-cycle arrest or apoptosis (oncogene addiction). MET gene amplification also occurs in vivo in a number of human gastric carcinomas, and clinical trials are now ongoing to assess the therapeutic efficacy of Met inhibitors in this type of malignancy. The aim of our study was to identify a preclinical algorithm of soluble surrogate biomarkers indicative of response to Met inhibition in gastric tumors, as a potential tool to integrate imaging criteria during patient follow-up. We started from a survey of candidate molecules based on antibody proteomics and gene expression profiling; after ELISA validation and analytical quantification, four biomarkers were identified that appeared to be strongly and consistently modulated by Met inhibition in a panel of Met-addicted gastric carcinoma cell lines, but not in Met-independent cell lines. Pharmacologic blockade of Met using specific small-molecule inhibitors led to reduced secretion of IL-8, GROα and the soluble form of uPAR and to increased production of IL-6 both in vitro (in culture supernatants) and in vivo (in the plasma of xenografted mice). If confirmed in patients, this information might prove useful to monitor clinical response to Met-targeted therapies in MET-amplified gastric carcinomas.

Potential benefits of aliskiren beyond blood pressure reduction

There is now clear evidence that reducing blood pressure (BP) with a broad range of agents, including angiotensin converting enzyme inhibitors and angiotensin receptor blockers, improves cardiovascular and renal outcomes. There is also evidence suggesting that these drugs have beneficial effects that are independent of BP lowering. Aliskiren is a direct renin inhibitor that interrupts the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step. Unlike angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, aliskiren produces a sustained reduction in plasma renin activity and reduces plasma levels of angiotensin II and aldosterone. Preclinical data and clinical trials in high-risk patients using surrogate markers increasingly suggest that aliskiren can reduce the progression of end-organ damage beyond that afforded by BP control. With its unique mechanism of action, combining aliskiren with another RAAS-blocking agent that has a different mechanism of action may provide more comprehensive blockade of the RAAS, potentially conferring additional clinical benefits. Evaluation of these end-organ effects in humans is underway in clinical trials designed to assess the effects of aliskiren alone and in combination with other antihypertensive agents on cardiovascular and renal outcomes.

Carotid MRI: a tool for monitoring individual response to cardiovascular therapy?

Stroke remains a leading cause of morbidity and mortality. While stroke-related mortality has declined over the past four decades, data indicate that the mortality rate has begun to plateau. This change in trend may be attributable to variation in individual response to therapies that were derived from population-based studies. Further reductions in stroke mortality may require individualized care governed by directly monitoring the effects of cardiovascular therapy. In this article, carotid MRI is considered as a tool for monitoring in vivo carotid atherosclerotic disease, a principal etiology of stroke. Carotid MRI has been previously utilized to identify specific plaque features beyond luminal stenosis that are predictive of transient ischemic attack and stroke. To gain perspective on the possibility of monitoring plaque change within the individual, clinical trials and natural history studies that have used serial carotid MRI are considered. Data from these studies indicate that patients with a lipid-rich necrotic core with or without intraplaque hemorrhage may represent the desired phenotype for monitoring treatment effects in the individual. Advances in tissue-specific sequences, acquisition resolution, scan time, and techniques for monitoring inflammation and mechanical forces are expected to enable earlier detection of response to therapy. In so doing, cost-effective multicenter studies can be conducted to confirm the anticipated positive effects on outcomes of using carotid MRI for individualized care in patients with carotid atherosclerosis. In accordance, carotid MRI is poised to emerge as a powerful clinical tool for individualized management of carotid atherosclerotic disease to prevent stroke.

Predicting visual outcomes for macular disease using optical coherence tomography

In recent years, the management of macular disease has undergone radical changes, in part because of new therapeutic approaches, but also due to the introduction of a new imaging modality - optical coherence tomography (OCT). The application of OCT imaging has clarified many aspects of chorioretinal disease pathophysiology and elucidated many hitherto unrecognized disease characteristics. From an early stage in its development, OCT has also been revolutionary in attempting to extract clinically useful measurements from image data in an automated fashion. As a result, OCT-derived measurements of retinal thickness have been rapidly embraced in clinical and research settings. However, as knowledge of OCT image analysis has developed, it has become increasingly clear that even accurate measurements of retinal thickness may fail to predict visual outcomes for many diseases. As a result, the focus of much current clinical imaging research is on the identification of other OCT-derived anatomic biomarkers predictive of visual outcomes - such biomarkers could serve as surrogate endpoints in clinical trials and provide prognostic information in clinical practice. In this review, we begin by highlighting the importance of accurate visual function assessment and describing the fundamentals of OCT image evaluation, before describing the current state-of-the-art with regard to predicting visual outcomes, for a variety of macular diseases, using OCT.

Cardiovascular risk-benefit profile of sibutramine

Sibutramine is a combined norepinephrine and serotonin reuptake inhibitor used as an antiobesity agent to reduce appetite and promote weight loss in combination with diet and exercise. At a daily dose of 10-20 mg, it was initially considered to have a good safety profile, as it does not induce primary pulmonary hypertension or adverse effects on cardiac valves, in contrast to previous reports relating to some other antiobesity agents. However, it exerts disparate effects on cardiovascular risk factors. On the one hand, sibutramine may have antiatherogenic activities, as it improves insulin resistance, glucose metabolism, dyslipidemia, and inflammatory markers, with most of these effects resulting from weight loss rather than from an intrinsic effect of the drug. On the other hand, because of its specific mode of action, sibutramine exerts a peripheral sympathomimetic effect, which induces a moderate increase in heart rate and attenuates the reduction in BP attributable to weight loss or even slightly increases BP. It may also prolong the QT interval, an effect that could induce arrhythmias. Because of these complex effects, it is difficult to conclude what the final impact of sibutramine on cardiovascular outcomes might be. Sibutramine has been shown to exert favorable effects on some surrogate cardiovascular endpoints such as reduction of left ventricular hypertrophy and improvement of endothelial dysfunction. A good cardiovascular safety profile was demonstrated in numerous 1- to 2-year controlled trials, in both diabetic and nondiabetic well selected patients, as well as in several observational studies. However, since 2002, several cardiovascular adverse events (hypertension, tachycardia, arrhythmias, and myocardial infarction) have been reported in sibutramine-treated patients. This led to a contraindication of the use of this antiobesity agent in patients with established coronary heart disease, previous stroke, heart failure, or cardiac arrhythmias. SCOUT (Sibutramine Cardiovascular and Diabetes Outcome Study) was designed to prospectively evaluate the efficacy/safety ratio of sibutramine in a high-risk population. The efficacy/safety results of the first 6-week lead-in open period of treatment with sibutramine 10 mg/day were reassuring in 10 742 overweight/obese high-risk subjects (97% had cardiovascular disease, 88% had hypertension, and 84% had type 2 diabetes mellitus). However, the final results of SCOUT showed that long-term (5 years') treatment with sibutramine (10-15 mg/day) exposed subjects with pre-existing cardiovascular disease to a significantly increased risk for nonfatal myocardial infarction and nonfatal stroke, but not cardiovascular death or all-cause mortality. Because the benefit of sibutramine as a weight-loss aid seems not to outweigh the cardiovascular risks, the European Medicines Agency recommended the suspension of marketing authorizations for sibutramine across the EU. The US FDA stated that the drug should carry a 'black box' warning due to an increased risk of stroke and heart attack in patients with a history of cardiovascular disease. In conclusion, concern still persists about the safety profile of sibutramine regarding cardiovascular outcomes, and the drug should not be prescribed for overweight/obese patients with a high cardiovascular risk profile.

Are changes in carotid intima-media thickness related to risk of nonfatal myocardial infarction? A critical review and meta-regression analysis

BACKGROUND

Carotid intima-media thickness (CIMT) is increasingly being used as a surrogate end point in randomized control trials (RCTs) of novel cardiovascular therapies. However, it remains unclear whether changes in CIMT that result from these therapies correlate with nonfatal myocardial infarction (MI).

METHODS

We performed a literature search of RCTs from 1990-2009 that used CIMT. Eligible RCTs (1) included quantitative and sequential assessments in CIMT at least 1 year apart and (2) reported nonfatal MI. Across RCTs, random-effects metaregression was employed to correlate differences in mean change in CIMT between treatment and control groups over time with the log odds ratios of developing nonfatal MI during follow-up.

RESULTS

Overall, we identified 28 RCTs with 15,598 patients. Differences in mean change in CIMT over time between treatment and control groups correlated with developing nonfatal MI during follow-up: for each 0.01 mm per year smaller rate of change in CIMT, the odds ratio for MI was 0.82 (95% CI, 0.69 to 0.96; P = .018). Results were similar in subgroups of RCTs with >1 year follow-up (P = .018) and those with at least 50 subjects in the treatment group (P = .019). However, there was no significant relationship between mean change in CIMT and nonfatal MI in RCTs evaluating statin therapy or those with high CIMTs at baseline (P > .20 in both instances).

CONCLUSIONS

Less progression in CIMT over time is associated with a lower likelihood of nonfatal MI in selected RCTs; however, these findings were inconsistent at times, suggesting caution in using CIMT as a surrogate end point.

Effects of retinal morphology on contrast sensitivity and reading ability in neovascular age-related macular degeneration

PURPOSE

To investigate the effect of changes in retinal morphology on contrast sensitivity and reading ability in patients with neovascular age-related macular degeneration (AMD) in the Avastin (bevacizumab; Genentech, South San Francisco, CA) for choroidal neovascularization (ABC) Trial.

METHODS

Contrast sensitivity obtained with Pelli-Robson charts, reading ability assessed with Minnesota Reading charts, and Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity (VA) obtained by protocol refraction, were recorded. Raw Stratus optical coherence tomography (OCT; Carl Zeiss Meditec, Inc., Dublin, CA) images were analyzed with the publicly available software OCTOR, which allows precise delineation of any retinal compartment of interest. Thickness and volume were calculated for neurosensory retina, subretinal fluid (SRF), subretinal tissue, and pigment epithelium detachment, and the resulting measurements were correlated with each visual function parameter.

RESULTS

One hundred twenty-two patients with newly diagnosed neovascular AMD and enrolled in the ABC Trial, were evaluated. Increased subretinal tissue volume correlated with decreased contrast sensitivity (Pearson's correlation coefficient, r = -0.4944, P = 0.001). A modest correlation was detected between SRF volume and contrast sensitivity (r = -0.2562, P = 0.004). Increased retinal thickness at the foveal center also correlated with decreased visual function (ETDRS VA: r = -0.4530, P < 0.001).

CONCLUSIONS

The strongest correlation detected between the functional parameters assessed and any of the OCT-derived morphologic parameters was that between decreased contrast sensitivity and increased subretinal tissue. In the future, assessment of contrast sensitivity and reading ability, in combination with quantitative subanalysis of retinal compartments, may lead to the identification of parameters relevant to functional improvement and ultimate prognosis in patients with newly diagnosed neovascular AMD (www.controlled-trials.com number, ISRCTN83325075).

Impact of waist circumference versus adiponectin level on subclinical atherosclerosis: a cross-sectional analysis in a sample from the general population

OBJECTIVE

Waist circumference is a clinical marker of obesity and an established risk factor for cardiovascular (CV) disease. Adiponectin, an adipocyte-derived hormone and new biomarker of obesity, was recently proposed as the missing link between obesity and increased cardiovascular risk. We evaluated waist and adiponectin in a middle-aged population-based cohort to compare the impact of both obesity-markers on subclinical atherosclerosis, in relation to other CV risk factors. DESIGN, SETTING & SUBJECTS: Seven noninvasive measurements of atherosclerosis (NIMA), as surrogate markers of (subclinical) atherosclerosis, were determined in 1517 participants of the Nijmegen Biomedical Study, aged 50-70 years, who were drawn from the Dutch community.

RESULTS

Both men and women with a high waist (M >104 cm; F >95 cm) showed increased pulse wave velocity (PWV) (M: +9.4%; F: +8.3%) and thicker intima-media thickness (IMT) (M: +7.3%; F: +4.3%) and women also showed increased plaque thickness (+16.6%). After adjustment for other CV risk factors both men and women showed increased IMT (M: +4.8%; F: +2.8%) and men also showed increased PWV (+9.6%). Both men and women with a low adiponectin level (M <2.2 mg L(-1); F <3.5 mg L(-1)) showed a decreased ankle-brachial index after exercise (M: -9.5%; F: -3.9%) and increased IMT (M: +3.7%; F: +3.6%) and women also showed increased PWV (+6.8%), but after adjustment for other CV risk factors low adiponectin level was no longer associated with deteriorated outcomes of NIMA.

CONCLUSIONS

Waist circumference showed independent associations with noninvasive measurements of subclinical atherosclerosis, whereas the association of adiponectin level with subclinical atherosclerosis was not independent of other CV risk factors. Prospective studies are needed to elucidate, if the atherogenic effect of a low adiponectin level is mediated by other CV risk factors and not by low adiponectin level intrinsically.