ACCLAIM: A randomized trial of abatacept (CTLA4-Ig) for relapsing-remitting multiple sclerosis.

BACKGROUND: Costimulatory blockade of T lymphocytes with the CTLA4-Ig fusion protein abatacept could be an effective treatment for the immune-mediated neuroinflammatory disease relapsing-remitting multiple sclerosis (RRMS). OBJECTIVE: To evaluate efficacy and safety of abatacept in RRMS. METHODS: ACCLAIM (A Cooperative Clinical Study of Abatacept in Multiple Sclerosis) was a Phase II, randomized, double-blind, placebo-controlled, multi-center trial. In all, 65 of 123 planned participants with RRMS were randomized to monthly intravenous infusions of abatacept or placebo for 24 weeks in a 2:1 ratio, switched to the opposite treatment at 28 weeks, and received their final dose of study medication at 52 weeks. Enrollment was closed early due to slow accrual. The primary endpoint was the mean number of new gadolinium-enhancing (Gd+) lesions obtained on magnetic resonance imaging (MRI) scans performed every 4 weeks. RESULTS: No statistically significant differences were observed in mean number of new Gd+ MRI lesions between the abatacept and placebo groups. No statistically significant differences were observed in other MRI and clinical parameters of RRMS disease activity. Abatacept was well tolerated. CONCLUSION: The ACCLAIM study did not demonstrate efficacy of abatacept in reducing the number of new Gd+ MRI lesions, or clinical measures of disease activity in RRMS.

The doubly labeled water method produces highly reproducible longitudinal results in nutrition studies.

The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reproducibility of the DLW method using 2 protocols developed and implemented in a multicenter clinical trial-the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE). To document the longitudinal reproducibility of the DLW method, 2 protocols, 1 based on repeated analysis of dose dilutions over the course of the clinical trial (dose-dilution protocol) and 1 based on repeated but blinded analysis of randomly selected DLW studies (test-retest protocol), were carried out. The dose-dilution protocol showed that the theoretical fractional turnover rates for (2)H and (18)O and the difference between the 2 fractional turnover rates were reproducible to within 1% and 5%, respectively, over 4.5 y. The Bland-Altman pair-wise comparisons of the results generated from 50 test-retest DLW studies showed that the fractional turnover rates and isotope dilution spaces for (2)H and (18)O, and total energy expenditure, were highly reproducible over 2.4 y. Our results show that the DLW method is reproducible in longitudinal studies and confirm the validity of this method to measure energy expenditure, define energy intake prescriptions, and monitor adherence and body composition changes over the period of 2.5-4.4 y. The 2 protocols can be adopted by other laboratories to document the longitudinal reproducibility of their measurements to ensure the long-term outcomes of interest are meaningful biologically. This trial was registered at clinicaltrials.gov as NCT00427193.

Approaches for quantifying energy intake and %calorie restriction during calorie restriction interventions in humans: the multicenter CALERIE study.

Calorie restriction (CR) is a component of most weight loss interventions and a potential strategy to slow aging. Accurate determination of energy intake and %CR is critical when interpreting the results of CR interventions; this is most accurately achieved using the doubly labeled water method to quantify total energy expenditure (TEE). However, the costs and analytical requirements of this method preclude its repeated use in many clinical trials. Our aims were to determine 1) the optimal TEE assessment time points for quantifying average energy intake and %CR during long-term CR interventions and 2) the optimal approach for quantifying short-term changes in body energy stores to determine energy intake and %CR during 2-wk DLW periods. Adults randomized to a CR intervention in the multicenter CALERIE study underwent measurements of TEE by doubly labeled water and body composition at baseline and months 1, 3, and 6. Average %CR achieved during the intervention was 24.9 ± 8.7%, which was computed using an approach that included four TEE assessment time points (i.e., TEE(baseline, months 1, 3, and 6)) plus the 6-mo change in body composition. Approaches that included fewer TEE assessments yielded %CR values of 23.4 ± 9.0 (TEE(baseline,) months 3 and 6), 25.0 ± 8.7 (TEE(baseline,) months 1 and 6), and 20.9 ± 7.1% (TEE(baseline, month 6)); the latter approach differed significantly from approach 1 (P < 0.001). TEE declined 9.6 ± 9.9% within 2-4 wk of CR beginning and then stabilized. Regression of daily home weights provided the most reliable estimate of short-term change in energy stores. In summary, optimal quantification of energy intake and %CR during weight loss necessitates a TEE measurement within the first month of CR to capture the rapid reduction in TEE.

Limited contribution of common genetic variants to risk for liver injury due to a variety of drugs.

BACKGROUND AND AIMS: Drug-induced liver injury (DILI) is a serious adverse drug event that is suspected to have a heritable component. We carried out a genome-wide association study of 783 individuals of European ancestry who experienced DILI due to more than 200 implicated drugs. METHODS: DILI patients from the US-based Drug-Induced Liver Injury Network (n=401) and three international registries (n=382) were genotyped with the Illumina 1Mduo BeadChip and compared with population controls (n=3001). Potential associations were tested in 307 independent Drug-Induced Liver Injury Network cases. RESULTS: After accounting for known major histocompatibility complex risk alleles for flucloxacillin-DILI and amoxicillin/clavulanate-DILI, there were no genome-wide significant associations, including in the major histocompatibility complex region. Stratification of DILI cases according to clinical phenotypes (injury type, latency, age of onset) also did not show significant associations. An analysis of hepatocellular DILI (n=285) restricted to 193 single-nucleotide polymorphisms previously associated with autoimmune disease showed a trend association for rs7574865, in the vicinity of signal transducer and activator of transcription 4 (STAT4) (P=4.5×10(-4)). This association was replicated in an independent cohort of 168 hepatocellular DILI cases (P=0.011 and 1.5×10(-5) for combined cohorts). No significant associations were found with stratification by other clinical or demographic variables. CONCLUSION: Although not significant at the genome-wide level, the association between hepatocellular DILI and STAT4 is consistent with the emerging role of the immune system in DILI. However, the lack of genome-wide association study findings supports the idea that strong genetic determinants of DILI may be largely drug-specific or may reflect rare genetic variations, which were not assessed in our study.

Clinical and histopathologic features of fluoroquinolone-induced liver injury.

BACKGROUND & AIMS: Fluoroquinolone-induced liver injury is rare; no prospective studies of well-characterized case series have been published. We studied patients with fluoroquinolone-induced hepatotoxicity from the Drug-Induced Liver Injury Network (DILIN) to characterize injury patterns, outcomes, and associated features. METHODS: We identified subjects with fluoroquinolone hepatotoxicity enrolled in the DILIN from September 2004 to January 2010. Demographic, clinical, and laboratory data were analyzed by descriptive statistical methods. RESULTS: Of the 679 registrants in the DILIN prospective study, 12 had fluoroquinolone hepatotoxicity (6 ciprofloxacin, 4 moxifloxacin, 1 levofloxacin, and 1 gatifloxacin). Seven were women; median age was 57 years (range, 23-80 years), and median time from fluoroquinolone start to symptoms was only 4 days (range, 1-39 days). Nine patients developed symptoms on medication; 3 did so 2, 8, and 32 days after stopping the medication. Cases were equally distributed among hepatocellular injury (predominantly increased levels of alanine aminotransferase), cholestatic injury (predominantly increased levels of alkaline phosphatase), and both. Seven patients had immunoallergic features. Patients with mixed hepatocellular and cholestatic injury had mild disease without jaundice; all recovered. In contrast, 2 of 4 patients with hepatocellular injury and jaundice died, 1 of acute liver failure. One patient with cholestatic injury developed vanishing bile duct syndrome and required liver transplantation; another had a persistently increased serum level of alkaline phosphatase. CONCLUSIONS: Fluoroquinolone liver injury is rapid in onset and often has immunoallergic features, indicating a hypersensitivity reaction. The pattern of injury can be hepatocellular, cholestatic, or mixed; mixed cases are the least severe. Acute and chronic liver failure can occur.

Causality assessment in drug-induced liver injury using a structured expert opinion process: comparison to the Roussel-Uclaf causality assessment method.

UNLABELLED: Drug-induced liver injury (DILI) is largely a diagnosis of exclusion and is therefore challenging. The US Drug-Induced Liver Injury Network (DILIN) prospective study used two methods to assess DILI causality: a structured expert opinion process and the Roussel-Uclaf Causality Assessment Method (RUCAM). Causality assessment focused on detailed clinical and laboratory data from patients with suspected DILI. The adjudication process used standardized numerical and descriptive definitions and scored cases as definite, highly likely, probable, possible, or unlikely. Results of the structured expert opinion procedure were compared with those derived by the RUCAM approach. Among 250 patients with suspected DILI, the expert opinion adjudication process scored 78 patients (31%) as definite, 102 (41%) as highly likely, 37 (15%) as probable, 25 (10%) as possible, and 8 (3%) as unlikely. Among 187 enrollees who had received a single implicated drug, initial complete agreement was reached for 50 (27%) with the expert opinion process and for 34 (19%) with a five-category RUCAM scale (P = 0.08), and the two methods demonstrated a modest correlation with each other (Spearman's r = 0.42, P = 0.0001). Importantly, the RUCAM approach substantially shifted the causality likelihood toward lower probabilities in comparison with the DILIN expert opinion process. CONCLUSION: The structured DILIN expert opinion process produced higher agreement rates and likelihood scores than RUCAM in assessing causality, but there was still considerable interobserver variability in both. Accordingly, a more objective, reliable, and reproducible means of assessing DILI causality is still needed.

Development of adherence metrics for caloric restriction interventions.

BACKGROUND: objective measures are needed to quantify dietary adherence during caloric restriction (CR) while participants are freeliving. One method to monitor adherence is to compare observed weight loss to the expected weight loss during a prescribed level of CR. Normograms (graphs) of expected weight loss can be created from mathematical modeling of weight change to a given level of CR, conditional on the individual's set of baseline characteristics. These normograms can then be used by counselors to help the participant adhere to their caloric target. PURPOSE: (1) To develop models of weight loss over a year of caloric restriction-given demographics, and well-defined measurements of body mass index, total daily energy expenditure (TDEE) and %CR. (2) To utilize these models to develop normograms, given the level of caloric restriction prescribed, and measures of these variables. METHODS: Seventy-seven individuals completing a 6-12-month caloric restriction intervention (CALERIE) at three sites (Pennington Biomedical Research Center, Tufts University, and Washington University) and had body weight and body composition measured frequently. Energy intake (and %CR) was estimated from TDEE (by doubly labeled water) and body composition (by DXA) at baseline and months 1, 3, 6, and 12. Bodyweight was modeled to determine the predictors and distribution of the expected trajectory of percent weight change over 12 months of CR. RESULTS: As expected, CR was related to change in body weight. Controlling for time-varying measures, initially simple models of the functional form indicated that the trajectory of percent weight change was predicted by a nonlinear function of age, TDEE, %CR, and sex. Using these estimates, normograms for the weight change were developed. Our model estimates that the mean weight loss (% change from baseline weight) for an individual adherent to a 25% CR regimen is -10.9 ± 6.3% for females and -13.9 + 6.4% for men after 12 months. LIMITATIONS: There are several limitations. Sample sizes are small (n = 77), and, by design, the protocols, including prescribed CR, for the interventions differed by site, and not all subjects completed a year of follow-up. In addition, the inclusion of subjects by age and initial BMI was constricted, so that these results may not generalize to other populations including older and obese subjects. CONCLUSIONS: The trajectory of percent weight change during CR interventions in the presence of well-measured covariates can be modeled using simple nonlinear functions, and is related level of CR, the percent change in TDEE, gender, and age. Displayed on a normogram, individually tailored trajectories can be used by counselors and participants to monitor weight loss and adherence to a CR regimen.

Causes, clinical features, and outcomes from a prospective study of drug-induced liver injury in the United States.

BACKGROUND & AIMS: Idiosyncratic drug-induced liver injury (DILI) is among the most common causes of acute liver failure in the United States, accounting for approximately 13% of cases. A prospective study was begun in 2003 to recruit patients with suspected DILI and create a repository of biological samples for analysis. This report summarizes the causes, clinical features, and outcomes from the first 300 patients enrolled. METHODS: Patients with suspected DILI were enrolled based on predefined criteria and followed up for at least 6 months. Patients with acetaminophen liver injury were excluded. RESULTS: DILI was caused by a single prescription medication in 73% of the cases, by dietary supplements in 9%, and by multiple agents in 18%. More than 100 different agents were associated with DILI; antimicrobials (45.5%) and central nervous system agents (15%) were the most common. Causality was considered to be definite in 32%, highly likely in 41%, probable in 14%, possible in 10%, and unlikely in 3%. Acute hepatitis C virus (HCV) infection was the final diagnosis in 4 of 9 unlikely cases. Six months after enrollment, 14% of patients had persistent laboratory abnormalities and 8% had died; the cause of death was liver related in 44%. CONCLUSIONS: DILI is caused by a wide array of medications, herbal supplements, and dietary supplements. Antibiotics are the single largest class of agents that cause DILI. Acute HCV infection should be excluded in patients with suspected DILI by HCV RNA testing. The overall 6-month mortality was 8%, but the majority of deaths were not liver related.

Reliability of the Roussel Uclaf Causality Assessment Method for assessing causality in drug-induced liver injury.

UNLABELLED: The Roussel Uclaf Causality Assessment Method (RUCAM) was developed to quantify the strength of association between a liver injury and the medication implicated as causing the injury. However, its reliability in a research setting has never been fully explored. The aim of this study was to determine test-retest and interrater reliabilities of RUCAM in retrospectively-identified cases of drug induced liver injury. The Drug-Induced Liver Injury Network is enrolling well-defined cases of hepatotoxicity caused by isoniazid, phenytoin, clavulanate/amoxicillin, or valproate occurring since 1994. Each case was adjudicated by three reviewers working independently; after an interval of at least 5 months, cases were readjudicated by the same reviewers. A total of 40 drug-induced liver injury cases were enrolled including individuals treated with isoniazid (nine), phenytoin (five), clavulanate/amoxicillin (15), and valproate (11). Mean +/- standard deviation age at protocol-defined onset was 44.8 +/- 19.5 years; patients were 68% female and 78% Caucasian. Cases were classified as hepatocellular (44%), mixed (28%), or cholestatic (28%). Test-retest differences ranged from -7 to +8 with complete agreement in only 26% of cases. On average, the maximum absolute difference among the three reviewers was 3.1 on the first adjudication and 2.7 on the second, although much of this variability could be attributed to differences between the enrolling investigator and the external reviewers. The test-retest reliability by the same assessors was 0.54 (upper 95% confidence limit = 0.77); the interrater reliability was 0.45 (upper 95% confidence limit = 0.58). Categorizing the RUCAM to a five-category scale improved these reliabilities but only marginally. CONCLUSION: The mediocre reliability of the RUCAM is problematic for future studies of drug-induced liver injury. Alternative methods, including modifying the RUCAM, developing drug-specific instruments, or causality assessment based on expert opinion, may be more appropriate.

Drug-Induced Liver Injury Network (DILIN) prospective study: rationale, design and conduct.

BACKGROUND: Drug-induced liver injury (DILI) is an uncommon adverse drug reaction of increasing importance to the medical community, pharmaceutical industry, regulatory agencies and the general public. OBJECTIVES: The Drug-Induced Liver Injury Network (DILIN) was established to advance understanding and research into DILI by initiating a prospective registry of patients with bona fide DILI for future studies of host clinical, genetic, environmental and immunological risk factors. The DILIN was also charged with developing standardized nomenclature, terminology and causality assessment instruments. METHODS: Five clinical sites, a data coordinating centre and senior scientists from the National Institute of Diabetes and Digestive and Kidney Diseases initiated the DILIN prospective study in September 2004. Eligible patients are required to meet minimal laboratory or histological criteria within 6 months of DILI onset and have other competing causes of liver injury excluded. Patients in the general community setting with pre-existing HIV, hepatitis B virus or hepatitis C virus infections and/or abnormal baseline liver biochemistries are eligible for enrollment. In addition, subjects with liver injury due to herbal products are eligible to participate. Control patients without DILI are also to be recruited in the future. RESULTS: All referred subjects undergo an extensive review of available laboratory, pathology and imaging studies. Subjects who meet pre-defined eligibility criteria at the 6-month study visit are followed for 2 years to better define the natural history of chronic DILI. Causality assessment is determined by a panel of three hepatologists who independently assign a causality score ranging from 1 (definite) to 5 (unlikely) as well as a severity score ranging from 1 (mild) to 5 (fatal). During the first 3 years, 367 subjects were enrolled into the DILIN prospective study. CONCLUSION: DILIN is a multicentre research network charged with improving our understanding of the aetiologies, risk factors and outcomes of DILI in the US. The network is meeting the targeted enrollment of ten patients per month and is developing a repository of clinical data and biological samples for future studies of DILI pathogenesis and outcome.

2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial.

BACKGROUND: For several cardiometabolic risk factors, values considered within normal range are associated with an increased risk of cardiovascular morbidity and mortality. We aimed to investigate the short-term and long-term effects of calorie restriction with adequate nutrition on these risk factors in healthy, lean, or slightly overweight young and middle-aged individuals. METHODS: CALERIE was a phase 2, multicentre, randomised controlled trial in young and middle-aged (21-50 years), healthy non-obese (BMI 22·0-27·9 kg/m2) men and women done in three clinical centres in the USA. Participants were randomly assigned (2:1) to a 25% calorie restriction diet or an ad libitum control diet. Exploratory cardiometabolic risk factor responses to a prescribed 25% calorie restriction diet for 2 years were evaluated (systolic, diastolic, and mean blood pressure; plasma lipids; high-sensitivity C-reactive protein; metabolic syndrome score; and glucose homoeostasis measures of fasting insulin, glucose, insulin resistance, and 2-h glucose, area-under-the curve for glucose, and insulin from an oral glucose tolerance test) analysed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00427193. FINDINGS: From May 8, 2007, to Feb 26, 2010, of 238 participants that were assessed, 218 were randomly assigned to and started a 25% calorie restriction diet (n=143, 66%) or an ad libitum control diet (n=75, 34%). Individuals in the calorie restriction group achieved a mean reduction in calorie intake of 11·9% (SE 0·7; from 2467 kcal to 2170 kcal) versus 0·8% (1·0) in the control group, and a sustained mean weight reduction of 7·5 kg (SE 0·4) versus an increase of 0·1 kg (0·5) in the control group, of which 71% (mean change in fat mass 5·3 kg [SE 0·3] divided by mean change in weight 7·5 kg [0·4]) was fat mass loss. Calorie restriction caused a persistent and significant reduction from baseline to 2 years of all measured conventional cardiometabolic risk factors, including change scores for LDL-cholesterol (p<0·0001), total cholesterol to HDL-cholesterol ratio (p<0·0001), and systolic (p<0·0011) and diastolic (p<0·0001) blood pressure. In addition, calorie restriction resulted in a significant improvement at 2 years in C-reactive protein (p=0·012), insulin sensitivity index (p<0·0001), and metabolic syndrome score (p<0·0001) relative to control. A sensitivity analysis revealed the responses to be robust after controlling for relative weight loss changes. INTERPRETATION: 2 years of moderate calorie restriction significantly reduced multiple cardiometabolic risk factors in young, non-obese adults. These findings suggest the potential for a substantial advantage for cardiovascular health of practicing moderate calorie restriction in young and middle-aged healthy individuals, and they offer promise for pronounced long-term population health benefits. FUNDING: National Institute on Aging and National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

Effects of Two Years of Calorie Restriction on Aerobic Capacity and Muscle Strength.

PURPOSE: Calorie restriction (CR) improves health span and delays age-related diseases in many species. The multicenter Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) study was the first randomized controlled trial of CR in nonobese humans. The aim of this investigation was to determine the effects of CR on V˙O2max and muscle strength in the CALERIE trial. METHODS: Healthy, normal-weight, and mildly overweight women and men (n = 218, mean ± SE age = 37.9 ± 0.5 yr) were randomized to 25% CR or an ad libitum (AL) control condition in a 2:1 allocation (143 CR, 75 AL). V˙O2max was determined with an incremental treadmill test; the strength of the knee flexors and extensors was assessed by dynamometry at baseline, 1 yr, and 2 yr. RESULTS: The CR group achieved an average 11.9% ± 0.7% CR during the 2-yr intervention. Body weight decreased in CR (-7.7 ± 0.4 kg), but not AL (+0.2 ± 0.5 kg). Absolute V˙O2max (L·min) decreased at 1 and 2 yr with CR, whereas V˙O2max expressed relative to body mass increased at both time points (1 yr: +2.2 ± 0.4; 2 yr: +1.9 ± 0.5 mL·kg·min) and relative to AL. The CR group increased their treadmill test time and workload at 1 and 2 yr. Strength results in CR were similar, with decreases in absolute flexor and extensor strength, but increases when expressed relative to body mass. No changes were observed for V˙O2max expressed relative to lean body mass or leg lean mass. CONCLUSIONS: Two years of modest CR without a structured exercise component did not appear to compromise aerobic capacity in healthy nonobese adults. The clinical implications of the observed changes in V˙O2max and muscle strength will be important to explore in future studies.

Application of the Marginal Structural Model to Account for Suboptimal Adherence in a Randomized Controlled Trial.

BACKGROUND: There is considerable interest in adjusting for suboptimal adherence in randomized controlled trials. A per-protocol analysis, for example removes individuals who fail to achieve a minimal level of adherence. One can also reassign non-adherers to the control group, censor them at the point of non-adherence, or cross them over to the control. However, there are biases inherent in each of these methods. Here, we describe an application of causal modeling to address this issue. METHODS: The marginal structural model with inverse-probability weighting was implemented using a weighted generalized estimating equation model. Two ancillary models were developed to derive the weights. First, stepwise linear regression was used to model the observed percent weight loss, while stepwise logistic regression model was applied to model early discontinuation from the intervention. From these, participant- and time-specific weights were calculated. DISCUSSION: This model is complicated and requires careful attention to detail. Which variables to force into the ancillary models, how to construct interaction terms, and how to address time-dependent covariates must be considered. Nevertheless, it can be used to great effect to predict intervention effects at full adherence. Moreover, by contrasting these results against intention-to-treat results, insights can be gained into the intrinsic physiologic effect of the intervention. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00427193.

Safety of two-year caloric restriction in non-obese healthy individuals.

BACKGROUND: The extent to which sustained caloric restriction (CR) in healthy non-obese adults is safe has not been previously investigated. OBJECTIVE: Assess the safety and tolerability of sustained two-year CR intervention in healthy, non-obese adults. DESIGN: A multi-center, randomized controlled trial. Participants were randomized using a 2:1 allocation in favor of 25% CR vs. Ad-Libitum intake (AL). Adverse and serious adverse events (AE, SAE), safety laboratory tests, and other safety parameters were closely monitored. RESULTS: Three participants were withdrawn from the CR intervention because of the safety concerns. No deaths and one SAE was reported by participants in the CR group. Although the difference in AE between AL and CR groups was not significant, within the CR group, the incidence of nervous system (p = 0.02), musculoskeletal (p = 0.02) and reproductive system (p = 0.002) disorders was significantly higher in the normal-weight than in the overweight participants. At months 12 and 24, bone mineral densities at the lumbar spine, total hip, and femoral neck of participants in the CR group were significantly lower than in those in the AL group. CONCLUSIONS: Two-years of CR at levels achieved in CALERIE was safe and well tolerated. Close monitoring for excessive bone loss and anemia is important.

Effect of Two-Year Caloric Restriction on Bone Metabolism and Bone Mineral Density in Non-Obese Younger Adults: A Randomized Clinical Trial.

Although caloric restriction (CR) could delay biologic aging in humans, it is unclear if this would occur at the cost of significant bone loss. We evaluated the effect of prolonged CR on bone metabolism and bone mineral density (BMD) in healthy younger adults. Two-hundred eighteen non-obese (body mass index [BMI] 25.1 ± 1.7 kg/m(2) ), younger (age 37.9 ± 7.2 years) adults were randomly assigned to 25% CR (CR group, n = 143) or ad libitum (AL group, n = 75) for 2 years. Main outcomes were BMD and markers of bone turnover. Other outcomes included body composition, bone-active hormones, nutrient intake, and physical activity. Body weight (-7.5 ± 0.4 versus 0.1 ± 0.5 kg), fat mass (-5.3 ± 0.3 versus 0.4 ± 0.4 kg), and fat-free mass (-2.2 ± 0.2 versus -0.2 ± 0.2 kg) decreased in the CR group compared with AL (all between group p < 0.001). Compared with AL, the CR group had greater changes in BMD at 24 months: lumbar spine (-0.013 ± 0.003 versus 0.007 ± 0.004 g/cm(2) ; p < 0.001), total hip (-0.017 ± 0.002 versus 0.001 ± 0.003 g/cm(2) ; p < 0.001), and femoral neck (-0.015 ± 0.003 versus -0.005 ± 0.004 g/cm(2) ; p = 0.03). Changes in bone markers were greater at 12 months for C-telopeptide (0.098 ± 0.012 versus 0.025 ± 0.015 µg/L; p < 0.001), tartrate-resistant acid phosphatase (0.4 ± 0.1 versus 0.2 ± 0.1 U/L; p = 0.004), and bone-specific alkaline phosphatase (BSAP) (-1.4 ± 0.4 versus -0.3 ± 0.5 U/L; p = 0.047) but not procollagen type 1 N-propeptide; at 24 months, only BSAP differed between groups (-1.5 ± 0.4 versus 0.9 ± 0.6 U/L; p = 0.001). The CR group had larger increases in 25-hydroxyvitamin D, cortisol, and adiponectin and decreases in leptin and insulin compared with AL. However, parathyroid hormone and IGF-1 levels did not differ between groups. The CR group also had lower levels of physical activity. Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ∼31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span. Further long-term studies are needed to determine if CR-induced bone loss in healthy adults contributes to fracture risk and if bone loss can be prevented with exercise.

Effects of 2-year calorie restriction on circulating levels of IGF-1, IGF-binding proteins and cortisol in nonobese men and women: a randomized clinical trial.

Young-onset calorie restriction (CR) in rodents decreases serum IGF-1 concentration and increases serum corticosterone levels, which have been hypothesized to play major roles in mediating its anticancer and anti-aging effects. However, little is known on the effects of CR on the IGF-1 system and cortisol in humans. To test the sustained effects of CR on these key hormonal adaptations, we performed a multicenter randomized trial of a 2-year 25% CR intervention in 218 nonobese (body mass index between 22 and 27.8 kg m(-2) ) young and middle-aged (20-50 years age range) men and women. Average CR during the first 6 months was 19.5 ± 0.8% and 9.1 ± 0.7% over the next 18 months of the study. Weight loss averaged 7.6 ± 0.3 kg over the 2-years period of which 71% was fat mass loss (P < 0.0001). Average CR during the CR caused a significant 21% increase in serum IGFBP-1 and a 42% reduction in IGF-1:IGFBP-1 ratio at 2 years (P < 0.008), but did not change IGF-1 and IGF-1:IGFBP-3 ratio levels. Serum cortisol concentrations were slightly but significantly increased by CR at 1 year only (P = 0.003). Calorie restriction had no effect on serum concentrations of PDGF-AB and TGFß-1. We conclude, on the basis of the present and previous findings, that, in contrast to rodents, humans do not respond to CR with a decrease in serum IGF-1 concentration or with a sustained and biological relevant increase in serum cortisol. However, long-term CR in humans significantly and persistently increases serum IGFBP-1 concentration.

The Study of the Effects of Diet on Metabolism and Nutrition (STEDMAN) weight loss project: Rationale and design.

This paper outlines the rationale and design of the Study of the Effects of Diet on Metabolism and Nutrition (STEDMAN) weight loss project, in which detailed biologic profiling of three hundred and fifty obese individuals (body mass index (BMI): 30-50 kg/m(2)) will be conducted as they lose weight via seven distinct interventions. These profiles will be compared to those of fifty normal, healthy, control participants (BMI: 18.5-24.9 kg/m(2)). The interventions include the following: Roux-en-Y gastric bypass surgery, dietary interventions of differing macronutrient composition and diverse pharmacologic interventions. Outcome variables include eight conventional metabolites and CRP measured by standard clinical chemistry techniques, twenty hormones of energy balance and fuel homeostasis measured by radioimmunoassay (RIA) or by enzyme-linked Immunosorbent assay (ELISA), ten pro- and anti-inflammatory cytokines measured using Luminex xMAP technology, one hundred and one intermediary metabolites measured by targeted mass-spectrometry-based methods, and physiologic variables such as body composition measured by dual energy X-ray absorptiometry (DEXA), air displacement plethysmography, and abdominal computerized tomography (CT), insulin sensitivity measured by intravenous glucose tolerance test (IV-GTT) and metabolic rate measured by indirect calorimetry. Results from this study will expand our knowledge of the biology of obesity and weight regulation and may lead to targeted strategies for its treatment and control.

A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity.

BACKGROUND: Caloric restriction (CR), energy intake reduced below ad libitum (AL) intake, increases life span in many species. The implications for humans can be clarified by randomized controlled trials of CR. METHODS: To determine CR's feasibility, safety, and effects on predictors of longevity, disease risk factors, and quality of life in nonobese humans aged 21-51 years, 218 persons were randomized to a 2-year intervention designed to achieve 25% CR or to AL diet. Outcomes were change from baseline resting metabolic rate adjusted for weight change ("RMR residual") and core temperature (primary); plasma triiodothyronine (T3) and tumor necrosis factor-α (secondary); and exploratory physiological and psychological measures. RESULTS: Body mass index averaged 25.1 (range: 21.9-28.0 kg/m(2)). Eighty-two percent of CR and 95% of AL participants completed the protocol. The CR group achieved 11.7±0.7 %CR (mean ± standard error) and maintained 10.4±0.4% weight loss. Weight change in AL was negligible. RMR residual decreased significantly more in CR than AL at 12 months (p = .04) but not 24 months (M24). Core temperature change differed little between groups. T3 decreased more in CR at M12 and M24 (p < .001), while tumor necrosis factor-α decreased significantly more only at M24 (p = .02). CR had larger decreases in cardiometabolic risk factors and in daily energy expenditure adjusted for weight change, without adverse effects on quality of life. CONCLUSIONS: Sustained CR is feasible in nonobese humans. The effects of the achieved CR on correlates of human survival and disease risk factors suggest potential benefits for aging-related outcomes that could be elucidated by further human studies.

Interaction and intervention modeling: predicting and extrapolating the impact of multiple interventions.

PURPOSE: Methods called interaction and intervention modeling are presented. Interaction modeling examines the interactions between variables as the basis for predicting the impact of multiple variables on a target population and on populations with difference distributions of risk factors. Intervention modeling incorporates these interactions and aims to extrapolate the impact of multiple interventions to new populations. The aim is to develop methods that will be useful for modeling and comparing intervention strategies using existing data and standard statistical methods. METHODS: Traditional hypothesis testing methods used for randomized clinical trials and cohort studies and extrapolating the results to new populations are compared with interaction and intervention modeling methods. Interaction and intervention modeling utilizes the same data as the traditional approach but examines the impact of multiple simultaneous interactions and allows extrapolation of the results to populations with different prevalences and distributions of risk factors. An example using real data demonstrates the potential of interaction and intervention modeling to predict the impact of multiple interacting variables and to compare the impact of alternative interventions. RESULTS: The methods outlined take into account the impact of the magnitude of the relative risks, prevalence of risk factors, and interaction of risk variables when predicting the impact on a new population or extrapolating the results of one or more interventions on a new population. Traditional methods that do not take into account interactions are shown to produce different conclusions from the intervention modeling approach that incorporates interactions. The impact of the intervention modeling approach compared with the traditional approach will be quite variable depending on the prevalence of the risk factors and their extent of interaction. CONCLUSIONS: Studies designed to test a hypothesis treat most variables as potential confounding variables adjusting for their impact and their interactions as part of the analysis using traditional regression methods. Interaction and intervention modeling focuses on the interactions themselves and allows comparison of the effectiveness of alternative interventions.

Validity and reliability of activity measures in African-American girls for GEMS.

PURPOSE: To determine the reliability and validity of physical activity monitors and self-report instruments suitable for young African-American girls. METHODS: A validation study was conducted by the Girls health Enrichment Multi-site Studies (GEMS) research team to compare an accelerometer with a pedometer and two self-report instruments for assessing physical activity in African-American girls, age 8-9 yr. Girls (N= 68) attended two clinic visits spaced 4 d apart. Each girl wore a MTI/CSA accelerometer (used as the criterion standard for validity) and a pedometer simultaneously for four consecutive days. Girls completed on two occasions a 24-h physical activity checklist of yesterday and usual activities, including sedentary activities (GEMS Activity Questionnaire, GAQ), and a 3-d computerized self-report instrument (Activitygram). RESULTS: Girls were (mean +/- SD) 9.0 +/- 0.6 yr old and had a body mass index of 19.4 kg x m. Reliability measured by intraclass correlations (ICC) and Pearson correlation coefficients (r) were calculated for the MTI/CSA (ICC = 0.37, P< 0.0001), pedometer (ICC = 0.08, = 0.094), Activitygram (ICC = 0.24) (P = 0.005), and GAQ for physical (r = 0.80, P< 0.0001) and sedentary (r = 0.3-0.5, P< 0.005) activities. Significant Pearson correlations between the MTI/CSA and the other instruments, as a measure of validity, were observed for the 4-d average pedometer score (r = 0.47, P< 0.0001), 3-d average Activitygram score (r = 0.37, P= 0.002), and the average of the two yesterday and two usual GAQ activity scores for a subset of 18 physical activities questions (r = 0.27, = 0.03; and r = 0.29,P = 0.02, respectively). The MTI/CSA was uncorrelated with single day scores from the three other instruments. CONCLUSION: The reliability of the instruments tested was acceptable, except the pedometer. Validity correlations were significant when more than one day was used. Self-report instruments need further development for improved reliability and validity.