Alison Pedley

Bezlotoxumab for Prevention of Recurrent Clostridium difficile Infection

Background Clostridium difficile is the most common cause of infectious diarrhea in hospitalized patients. Recurrences are common after antibiotic therapy. Actoxumab and bezlotoxumab are human monoclonal antibodies against C. difficile toxins A and B, respectively. Methods We conducted two double‐blind, randomized, placebo‐controlled, phase 3 trials, MODIFY I and MODIFY II, involving 2655 adults receiving oral standard‐of‐care antibiotics for primary or recurrent C. difficile infection. Participants received an infusion of bezlotoxumab (10 mg per kilogram of body weight), actoxumab plus bezlotoxumab (10 mg per kilogram each), or placebo; actoxumab alone (10 mg per kilogram) was given in MODIFY I but discontinued after a planned interim analysis. The primary end point was recurrent infection (new episode after initial clinical cure) within 12 weeks after infusion in the modified intention‐to‐treat population. Results In both trials, the rate of recurrent C. difficile infection was significantly lower with bezlotoxumab alone than with placebo (MODIFY I: 17% [67 of 386] vs. 28% [109 of 395]; adjusted difference, ‐10.1 percentage points; 95% confidence interval [CI], ‐15.9 to ‐4.3; P<0.001; MODIFY II: 16% [62 of 395] vs. 26% [97 of 378]; adjusted difference, ‐9.9 percentage points; 95% CI, ‐15.5 to ‐4.3; P<0.001) and was significantly lower with actoxumab plus bezlotoxumab than with placebo (MODIFY I: 16% [61 of 383] vs. 28% [109 of 395]; adjusted difference, ‐11.6 percentage points; 95% CI, ‐17.4 to ‐5.9; P<0.001; MODIFY II: 15% [58 of 390] vs. 26% [97 of 378]; adjusted difference, ‐10.7 percentage points; 95% CI, ‐16.4 to ‐5.1; P<0.001). In prespecified subgroup analyses (combined data set), rates of recurrent infection were lower in both groups that received bezlotoxumab than in the placebo group in subpopulations at high risk for recurrent infection or for an adverse outcome. The rates of initial clinical cure were 80% with bezlotoxumab alone, 73% with actoxumab plus bezlotoxumab, and 80% with placebo; the rates of sustained cure (initial clinical cure without recurrent infection in 12 weeks) were 64%, 58%, and 54%, respectively. The rates of adverse events were similar among these groups; the most common events were diarrhea and nausea. Conclusions Among participants receiving antibiotic treatment for primary or recurrent C. difficile infection, bezlotoxumab was associated with a substantially lower rate of recurrent infection than placebo and had a safety profile similar to that of placebo. The addition of actoxumab did not improve efficacy. (Funded by Merck; MODIFY I and MODIFY II ClinicalTrials.gov numbers, NCT01241552 and NCT01513239.)

The ratio of visceral to subcutaneous fat, a metric of body fat distribution, is a unique correlate of cardiometabolic risk

Aims/hypothesisThe anatomic location of excess body fat has an impact on associated cardiometabolic morbidity, and visceral adipose tissue (VAT) is more pathogenic than subcutaneous adipose tissue (SAT). However, VAT or SAT alone provides little information regarding the relative distribution of body fat. We hypothesised that the propensity to store energy in VAT relative to SAT depots may be a correlate of cardiometabolic risk, and tested this hypothesis using the VAT/SAT ratio as a metric of fat distribution.MethodsWe investigated associations of the VAT/SAT ratio with cardiometabolic traits in 3,223 participants (48% women) from the Framingham Heart Study. Fat depots were quantified by multidetector computed tomography (CT) scanning.ResultsIn women and men, higher VAT/SAT ratio was associated (p < 0.05) with most assessed cardiovascular risk factors reflecting blood pressure, dyslipidaemia and insulin resistance. Additional adjustment for BMI did not materially change the findings in women, and generally strengthened associations in men. Further adjustment for VAT attenuated some associations in women, but those with lower HDL-cholesterol, higher triacylglycerol (both p < 0.0001) and higher prevalence of hypertension (p = 0.02), diabetes (p = 0.01) and the metabolic syndrome (p = 0.005) remained significant. Similarly, in men, associations with higher systolic (p = 0.006) and diastolic blood pressure (p = 0.03), higher fasting glucose (p = 0.0005), lower HDL-cholesterol and higher triacylglycerol (both p < 0.0001) and higher prevalence of diabetes (p = 0.006) remained significant.Conclusions/interpretationVAT/SAT ratio is a correlate of cardiometabolic risk, above and beyond BMI and VAT. The propensity to store fat viscerally versus subcutaneously may be a unique risk factor independent of absolute fat volumes.

Visceral and Subcutaneous Fat Quality and Cardiometabolic Risk

OBJECTIVES The aim of this study was to evaluate whether computed tomography (CT) attenuation, as a measure of fat quality, is associated with cardiometabolic risk factors above and beyond fat quantity. BACKGROUND Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) are pathogenic fat depots associated with cardiometabolic risk. Adipose tissue attenuation in CT images is variable, similar to adipose tissue volume. However, whether the quality of abdominal fat attenuation is associated with cardiometabolic risk independent of the quantity is uncertain. METHODS Participants were drawn from the Framingham Heart Study CT substudy. The VAT and SAT volumes were acquired by semiquantitative assessment. Fat quality was measured by CT attenuation and recorded as mean Hounsfield unit (HU) within each fat depot. Sex-specific linear and logistic multivariable regression models were used to assess the association between standard deviation (SD) decrease in HU and each risk factor. RESULTS Lower CT attenuation of VAT and SAT was correlated with higher body mass index levels in both sexes. Risk factors were generally more adverse with decreasing HU values. For example, in women, per 1 SD decrease in VAT HU, the odds ratio (OR) was increased for hypertension (OR: 1.80), impaired fasting glucose (OR: 2.10), metabolic syndrome (OR: 3.65), and insulin resistance (OR: 3.36; all p < 0.0001). In models that further adjusted for VAT volume, impaired fasting glucose, metabolic syndrome, and insulin resistance remained significant. Trends were similar but less pronounced for SAT and for men. There was evidence of an interaction between HU and fat volume among both women and men. CONCLUSIONS Lower CT attenuation of VAT and SAT is associated with adverse cardiometabolic risk above and beyond total adipose tissue volume. Qualitative indices of abdominal fat depots may provide insight regarding cardiometabolic risk independent of fat quantity.

Association Between Visceral and Subcutaneous Adipose Depots and Incident Cardiovascular Disease Risk Factors

Background— Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) vary in volume and quality. We evaluated whether fat volume or attenuation (indirect measure of quality) predicts metabolic risk factor changes. Methods and Results— Framingham Heart Study Multi-detector Computed Tomography Substudy participants (n=1730, 45% women) were followed up over a mean of 6.2 years. Baseline VAT and SAT volume (in cm3) and attenuation (in Hounsfield units) were assessed. Outcomes included blood pressure, lipids, and glucose. We constructed multivariable regression models predicting change from baseline to follow-up. Baseline VAT was associated with metabolic risk factors at follow-up. Per 500-cm3 increase in baseline VAT, glucose was 2.34 mg/dL higher (95% confidence interval, 1.71–2.97) and high-density lipoprotein was 1.62 mg/dL lower (95% confidence interval, 0.97–2.28) in women (P<0.0001 for both). These findings remained significant after adjustment for body mass index. Results for SAT were similar although less striking. Lower (more negative) fat attenuation was associated with more adverse metabolic profiles at follow-up. For example, per 5-unit decrease in baseline VAT Hounsfield units, log triglycerides increased by 0.08 mg/dL (95% confidence interval, 0.05–0.12; P=0.005), which remained significant after adjustment for baseline VAT. Among men, VAT and SAT Hounsfield units were associated with changes in cardiovascular disease risk factors but were mostly attenuated after baseline volume adjustment. Conclusions— VAT volume and SAT volume are associated with incident metabolic risk factors beyond overall adiposity. Decreases in fat attenuation are also associated with incident risk factors. These findings suggest that both volume and quality of VAT and SAT contribute to metabolic risk.

Association of Female Reproductive Factors with Body Composition: The Framingham Heart Study

BACKGROUND Identifying reproductive risk factors in women offers a life course approach to obesity and cardiovascular disease prevention. The association of female reproductive factors with measures of regional body fat distribution has not been comprehensively studied. METHODS We examined the association of female reproductive factors (age at menarche, parity, age at natural menopause, menopausal status) in association with body composition data from women who participated in the Offspring and the Third Generation Framingham Heart Study cohorts. Visceral adipose tissue (VAT) and sc adipose tissue (SAT) were measured volumetrically by multidetector computerized tomography. We modeled the relationship between each fat depot and female reproductive factors after adjusting for various factors such as age, smoking status, alcohol intake, physical activity index, hormone replacement therapy, and menopausal status. RESULTS Earlier age at menarche was associated with increased body mass index (BMI), waist circumference (WC), VAT, and SAT (P < 0.0001). This association of earlier menarche with adiposity measures was attenuated after adjusting for BMI (all P > 0.70). We observed no association between parity and all parameters of adiposity measurements (all P > 0.24). Similarly, age at natural menopause was not associated with measures of body composition. Despite higher mean BMI among the post- (BMI 27.3 kg/m(2)) compared with the premenopausal women (BMI 25.9 kg/m(2)) in an age-matched analysis, mean VAT was not different between the two groups (P = 0.30). CONCLUSIONS Earlier menarche is associated with overall obesity but not with VAT or SAT after accounting for measures of generalized adiposity. Parity and menopausal age were not associated with adiposity measures. Although postmenopausal women had increased BMI, VAT, and SAT, the association was predominantly due to age.

Intramuscular Fat and Associations With Metabolic Risk Factors in the Framingham Heart Study

Objective—Intramuscular fat accumulates between muscle fibers or within muscle cells. We investigated the association of intramuscular fat with other ectopic fat deposits and metabolic risk factors. Approach and Results—Participants (n=2945; 50.2% women; mean age 50.8 years) from the Framingham Heart Study underwent multidetector computed tomography scanning of the abdomen. Regions of interest were placed on the left and right paraspinous muscle, and the muscle attenuation (MA) in Hounsfield units was averaged. We examined the association between MA and metabolic risk factors in multivariable models, and additionally adjusted for body mass index (BMI) and visceral adipose tissue (VAT) in separate models. MA was associated with dysglycemia, dyslipidemia, and hypertension in both sexes. In women, per standard deviation decrease in MA, there was a 1.34 (95% confidence interval, 1.10–1.64) increase in the odds of diabetes mellitus, a 1.40 (95% confidence interval, 1.22–1.61) increase in the odds of high triglycerides, and a 1.29 (95% confidence interval, 1.12–1.48) increase in the odds of hypertension. However, none of these associations persisted after adjustment for BMI or VAT. In men, we observed similar patterns for most risk factors. The exception was metabolic syndrome, which retained association in women even after adjustment for BMI and VAT, and low high density lipoprotein and high triglycerides in men, whose associations also persisted after adjustment for BMI and VAT. Conclusions—MA was associated with metabolic risk factors, but most of these associations were lost after adjustment for BMI or VAT. However, a unique association remained for metabolic syndrome in women and lipids in men.

Fat Quality and Incident Cardiovascular Disease, All-Cause Mortality, and Cancer Mortality

CONTEXT Cellular characteristics of fat quality have been associated with cardiometabolic risk and can be estimated by computed tomography (CT) attenuation. OBJECTIVE The aim was to determine the association between CT attenuation (measured in Hounsfield units [HU]) and clinical outcomes. METHODS This was a prospective community-based cohort study using data from the Framingham Heart Study (n = 3324, 48% women, mean age 51 years) and Cox proportional hazard models. MAIN OUTCOMES The primary outcomes of interest were incident cardiovascular disease (CVD) and all-cause mortality. The secondary outcomes of interest were incident cancer, non-CVD death, and cancer death. RESULTS There were 111 incident CVD events, 137 incident cancers, 85 deaths including 69 non-CVD deaths, and 45 cancer deaths in up to 23 047 person-years of follow-up. A 1-SD increment in visceral adipose tissue (VAT) HU was inversely associated with incident CVD in the age- and sex-adjusted model (hazard ratio [HR] 0.78, P = .02) but not after multivariable adjustment (HR 0.83, P = .11). VAT HU was directly associated with all-cause mortality (multivariable HR 1.40, P = .003), which maintained significance after additional adjustment for body mass index (HR 1.53, P < .001) and VAT volume (HR 1.99, P < .001). Non-CVD death remained significant in all 3 models, including after adjustment for VAT volume (HR 1.97, P < .001). VAT HU was also associated with cancer mortality (HR 1.93, P = .002). Similar results were obtained for sc adipose tissue HU. CONCLUSIONS Fat quality, as estimated by CT attenuation, is associated with all-cause mortality, non-CVD death, and cancer death. These associations highlight how indirect indices of fat quality can potentially add to a better understanding of obesity-related complications.

Prevalence, Distribution, and Risk Factor Correlates of High Thoracic Periaortic Fat in the Framingham Heart Study

Background Thoracic periaortic adipose tissue (TAT) is associated with atherosclerosis and cardiovascular disease (CVD) risk factors and may play a role in obesity‐mediated vascular disease. We sought to determine the prevalence, distribution, and risk factor correlates of high TAT. Methods and Results Participants from the Framingham Heart Study (n=3246, 48% women, mean age 51.1 years) underwent multidetector computed tomography; high TAT and visceral adipose tissue (VAT) were defined on the basis of sex‐specific 90th percentiles in a healthy referent sample. The prevalence of high TAT was 38.1% in women and 35.7% in men. Among individuals without high VAT, 10.1% had high TAT. After adjustment for age and VAT, both women and men with high TAT in the absence of high VAT were older and had a higher prevalence of CVD (P<0.0001) compared with those without high TAT. In addition, men in this group were more likely to be smokers (P=0.02), whereas women were more likely to have low high‐density lipoprotein cholesterol (P=0.005). Conclusions Individuals in our community‐based sample with high TAT in the absence of high VAT were characterized by an adverse cardiometabolic profile. This adipose tissue phenotype may identify a subset of individuals with distinct metabolic characteristics.

Phase 2, Dose-Ranging Study of Relebactam with Imipenem/Cilastatin in Subjects with Complicated Intra-Abdominal Infection

ABSTRACT Relebactam (REL [MK-7655]) is a novel class A/C β-lactamase inhibitor intended for use with imipenem for the treatment of Gram-negative bacterial infections. REL restores imipenem activity against some resistant strains of Klebsiella and Pseudomonas. In this multicenter, double-blind, controlled trial (NCT01506271), subjects who were ≥18 years of age with complicated intra-abdominal infection were randomly assigned (1:1:1) to receive 250 mg REL, 125 mg REL, or placebo, each given intravenously (i.v.) with 500 mg imipenem-cilastatin (IMI) every 6 h (q6h) for 4 to 14 days. The primary efficacy endpoint was the proportion of microbiologically evaluable (ME) subjects with a favorable clinical response at discontinuation of i.v. therapy (DCIV). A total of 351 subjects were randomized, 347 (99%) were treated, and 255 (73%) were ME at DCIV (55% male; mean age, 49 years). The most common diagnoses were complicated appendicitis (53%) and complicated cholecystitis (17%). Thirty-six subjects (13%) had imipenem-resistant Gram-negative infections at baseline. Both REL doses plus IMI were generally well tolerated and demonstrated safety profiles similar to that of IMI alone. Clinical response rates at DCIV were similar in subjects who received 250 mg REL plus IMI (96.3%) or 125 mg REL plus IMI (98.8%), and both were noninferior to IMI alone (95.2%; one-sided P < 0.001). The treatment groups were also similar with respect to clinical response at early and late follow-up and microbiological response at all visits. Pharmacokinetic/pharmacodynamic simulations show that imipenem exposure at the proposed dose of 500 mg IMI with 250 mg REL q6h provides coverage of >90% of carbapenem-resistant bacterial strains.

Association of Fat Density With Subclinical Atherosclerosis

Background Ectopic fat density is associated with cardiovascular disease (CVD) risk factors above and beyond fat volume. Volumetric measures of ectopic fat have been associated with CVD risk factors and subclinical atherosclerosis. The aim of this study was to investigate the association between fat density and subclinical atherosclerosis. Methods and Results Participants were drawn from the Multi‐Detector Computed Tomography (MDCT) substudy of the Framingham Heart Study (n=3079; mean age, 50.1 years; 49.2% women). Fat density was indirectly estimated by computed tomography attenuation (Hounsfield Units [HU]) on abdominal scan slices. Visceral fat (VAT), subcutaneous fat (SAT), and pericardial fat HU and volumes were quantified using standard protocols; coronary and abdominal aortic calcium (CAC and AAC, respectively) were measured radiographically. Multivariable‐adjusted logistic regression models were used to evaluate the association between adipose tissue HU and the presence of CAC and AAC. Overall, 17.1% of the participants had elevated CAC (Agatston score [AS]>100), and 23.3% had elevated AAC (AS>age‐/sex‐specific cutoffs). Per 5‐unit decrement in VAT HU, the odds ratio (OR) for elevated CAC was 0.76 (95% confidence interval [CI], 0.65 to 0.89; P=0.0005), even after adjustment for body mass index or VAT volume. Results were similar for SAT HU. With decreasing VAT HU, we also observed an OR of 0.79 (95% CI, 0.67 to 0.92; P=0.004) for elevated AAC after multivariable adjustment. We found no significant associations between SAT HU and AAC. There was no significant association between pericardial fat HU and either CAC or AAC. Conclusions Lower VAT and SAT HU, indirect estimates of fat quality, are associated with a lower risk of subclinical atherosclerosis.