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Results for “Surrogate variables analysis”

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PubMed2005

Serum hepatocyte growth factor levels predict long-term clinical outcome after percutaneous coronary revascularization.

AIMS: To evaluate, in patients referred for elective percutaneous coronary revascularization (PCR) without heparin pre-treatment, the relationship between baseline serum levels of the angiogenic growth factors, vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF), and clinical outcome. METHODS AND RESULTS: In 488 consecutive patients undergoing elective coronary angioplasty, hsC-reactive protein, HGF, and VEGF levels were measured before heparin administration. The primary endpoint, a composite of death and myocardial infarction, occurred in 44 patients at a median follow-up of 14.9 months. At baseline, VEGF levels were related to C-reactive protein levels and inversely related to age; HGF levels were related to C-reactive protein levels, diabetes, and recent clinical instability. In the univariate analysis, HGF had a significant positive relationship (P=0.003) with the primary endpoint. A similar trend was observed for VEGF (P=0.11). The only three variables significantly associated with the primary endpoint in the multivariable Cox model were HGF (P=0.004), C-reactive protein (P=0.007), and diabetes (P=0.04). CONCLUSION: Our results demonstrate that in patients, without heparin pre-treatment, referred for PCR, a high serum level of HGF is an independent predictor of clinical events during follow-up and is correlated with other surrogate measures of the activity of atherosclerosis.

Aged↗

PubMed2005

Is 24-hour urinary calcium a surrogate marker for dietary calcium intake?

OBJECTIVES: To determine whether the 24-hour urinary excretion of calcium was a reliable surrogate marker for dietary calcium intake. Although dietary calcium intake has been negatively correlated with the risk of recurrent calcium-based stones, detailed dietary histories are not routinely evaluated in most patients with recurrent stone formation. METHODS: The dietary records and corresponding 24-hour urine collections of 68 randomly selected women with a history of calcium-based renal stones and two or more outpatient clinic visits were studied. Subjects were excluded if they had conditions or took medications affecting calcium absorption or excretion. Multivariate regression analysis was performed on the most recent set of data per patient with 24-hour urinary calcium as the dependent variable. Independent variables included age, weight, and dietary calcium, sodium, potassium, magnesium, fiber, and animal protein. Regression analysis was performed on the differences between the first and last visits for dietary and urinary data. Using tertiles, the positive predictive value of 24-hour urinary calcium for the respective dietary intake tertiles was calculated. RESULTS: The regression model on absolute values showed all dietary parameters to have squared partial correlation coefficients of less than 0.3 (P = 0.015, R2 = 0.264). In the second regression analysis, the model did not significantly explain the variance (P = 0.656). The positive predictive value of a mean 24-hour urinary calcium level less than 3.75 mmol/L for calcium intake less than 585 mg/day was 45%. CONCLUSIONS: The results of the present study revealed that the 24-hour urinary calcium cannot be used as a surrogate marker for dietary intake of calcium. A detailed dietary history is needed for all women with recurrent stone formation for proper assessment and potential modification of calcium intake to reduce recurrences.

Biomarkers↗

PubMed1997

The informed consent process in older patients who developed delirium: a clinical epidemiologic study.

PURPOSE: Delirium, defined as an acute, fluctuating disorder of attention and cognition, is a serious and increasingly common problem for hospitalized older persons. Delirium poses unique ethical challenges for the informed consent process, notably the preservation of patient autonomy in the face of potentially fluctuating decision-making capacity. To clarify these issues, we examined the informed consent process in a group of hospitalized older patients who developed delirium. PATIENTS: Eighty-four hospitalized patients aged >70 years who developed delirium during hospitalization at a large urban teaching hospital. METHODS: We conducted a clinical epidemiologic investigation of informed consent in 173 medical and surgical procedures performed in 84 patients. Clinical researchers carried out detailed cognitive evaluation of patients on or near the consent date. A separate blinded researcher extracted medical record information on the procedures and informed consent process variables. RESULTS: Of 173 procedures, 33 (19%) had no documentation of any consent, and 34 (20%) used surrogate consent. There were no documented assessments of competency/ decisional capacity; cognitive assessments were done in 7 (4%) cases, and legal consults in 2 (1%) cases. Discussion of potential risks of the procedure with patient or surrogate were documented in 61 (35%) cases. In multivariable analysis, independent predictors for failure to obtain consent were presence of delirium (adjusted odds ratio [OR] = 2.7, 95% confidence interval [CI] 1.3, 5.3) and less invasive procedure (OR = 5.0, CI 2.0, 12.8). Although cognitive impairment predicted surrogate use, we found that 47% of cases with substantial impairment did not involve use of a surrogate, whereas surrogates signed for 4% of cases with normal mental status near the time of consent. CONCLUSIONS: Our results highlight the ethical challenges that delirium poses for the informed consent process, including the high rate of no consent, lack of cognitive and decisional capacity assessment, and inconsistent surrogate use.

Aged↗

PubMed2005

Cardiac baroreceptor sensitivity: a prognostic marker in predialysis chronic kidney disease patients?

BACKGROUND: Small, uncontrolled studies of dialysis-dependent chronic kidney disease (CKD) patients have demonstrated abnormalities of cardiovascular autonomic control and vascular compliance, which may contribute to adverse cardiovascular morbidity in this population. However, there is little information utilizing newer, noninvasive techniques in predialysis patients with increasing degrees of uremia. METHODS: One hundred and five nondialysis CKD patients with a median GFR of 23 mL/min/1.73 m(2) (range: 6 to 102) at baseline were studied. Cardiac baroreceptor sensitivity (BRS) was recorded by time- and frequency-domain techniques, and its relationship with increasing degrees of uremia studied. During a mean follow-up period of 42 months (range: 3 to 70), primary (death, dialysis, transplantation) and secondary (fatal and nonfatal cardiovascular events) outcome measures were recorded. The importance of cardiac BRS in comparison to other important renal and cardiovascular prognostic variables in predicting outcome was assessed. RESULTS: Median cardiac BRS by time domain analysis at baseline was 8.85 msec/mm Hg (interquartile range: 6.85), and impaired cardiac BRS was related to reduced GFR, increasing age, and hypertension on quantile regression analysis. 'Impaired' cardiac BRS was associated with a trend toward increased likelihood of both primary and secondary outcomes, and may act as a surrogate measure of other cardiovascular risk factors, including age, hyperlipidemia, hypertension, previous cardiovascular disease, and doubling of creatinine. CONCLUSION: Nondialysis-dependent CKD patients have impaired cardiac BRS, and this was related to decreasing GFR. There was a trend toward poorer prognosis in patients with impaired cardiac BRS that requires further study. Cardiac BRS may provide a simple, bedside, noninvasive assessment of overall cardiovascular risk in this population.

Adult↗

PubMedDate not supplied

[Functional variability of the autocorrelation structure of the EEG].

On an example of records EEG of 39 healthy subjects, the quantitative analysis of variability of the autocorrelation structure of one-second EEG segments was carried out on the basis of comparison of structural functions constructed for these segments. It was shown that more than 30% of cases, statistically significant sifferences were observed between the structural functions of successive one-second EEG segments shifted by 1-3 s, as compared to surrogate EEGs formed with the tangled random sequence of count points. On the basis of the obtained data, the index of nonstationarity of the EEG autocorrelation structure was proposed. This index can be used for the objective quantitative evaluation of the functional states of the human brain.

Brain↗

PubMed2002

Fractal dimensions of laser doppler flowmetry time series.

Laser Doppler flowmetry (LDF) provides a non-invasive method of assessing cutaneous perfusion. As the microvasculature under the probe is not defined the measured flux cannot be given absolute units, but the technique has nevertheless proved valuable for assessing relative changes in perfusion in response to physiological stress. LDF signals normally show pronounced temporal variability, both as a consequence of the pulsatile nature of blood flow and local changes in dynamic vasomotor activity. The aim of the present study was to investigate the use of methods of nonlinear analysis in characterizing temporal fluctuations in LDF signals. Data were collected under standardised conditions from the forearm of 16 normal subjects at rest, during exercise and on recovery. Surrogate data was then generated from the original time series by phase randomization. Dispersional analysis demonstrated that the LDF data was fractal with two distinct scaling regions, thus allowing the calculation of a fractal dimension which decreased significantly from 1.23 +/- 0.09 to 1.04 +/- 0.02 during exercise. By contrast, dispersional analysis of the surrogate data showed no scaling region.

Adolescent↗

PubMed2003

Estimating long-term average particulate air pollution concentrations: application of traffic indicators and geographic information systems.

BACKGROUND: As part of a multicenter study relating traffic-related air pollution with incidence of asthma in three birth cohort studies (TRAPCA), we used a measurement and modelling procedure to estimate long-term average exposure to traffic-related particulate air pollution in communities throughout the Netherlands; in Munich, Germany; and in Stockholm County, Sweden. METHODS: In each of the three locations, 40-42 measurement sites were selected to represent rural, urban background and urban traffic locations. At each site and fine particles and filter absorbance (a marker for diesel exhaust particles) were measured for four 2-week periods distributed over approximately 1-year periods between February 1999 and July 2000. We used these measurements to calculate annual average concentrations after adjustment for temporal variation. Traffic-related variables (eg, population density and traffic intensity) were collected using Geographic Information Systems and used in regression models predicting annual average concentrations. From these models we estimated ambient air concentrations at the home addresses of the cohort members. RESULTS: Regression models using traffic-related variables explained 73%, 56% and 50% of the variability in annual average fine particle concentrations for the Netherlands, Munich and Stockholm County, respectively. For filter absorbance, the regression models explained 81%, 67% and 66% of the variability in the annual average concentrations. Cross-validation to estimate the model prediction errors indicated root mean squared errors of 1.1-1.6 microg/m for PM(2.5) and 0.22-0.31 *10(-5) m for absorbance. CONCLUSIONS: A substantial fraction of the variability in annual average concentrations for all locations was explained by traffic-related variables. This approach can be used to estimate individual exposures for epidemiologic studies and offers advantages over alternative techniques relying on surrogate variables or traditional approaches that utilize ambient monitoring data alone.

Air Pollutants↗

PubMed2005

Predictors of wound infection in ventral hernia repair.

BACKGROUND: Postoperative wound infection is a significant risk factor for recurrence after ventral hernia repair (VHR). The current study examines patient- and procedure-specific variables associated with wound infection. METHODS: A cohort of subjects undergoing VHR from 13 regional Veterans Health Administration (VHA) sites was identified. Patient-specific risk variables were obtained from National Surgical Quality Improvement Program (NSQIP) data. Operative variables were obtained from physician-abstracted operative notes. Univariate and multivariable logistic regression analysis was used to model predictors of postoperative wound infection. RESULTS: A total of 1505 VHR cases were used for analysis; wound infection occurred in 5% (n = 74). Best-fit logistic regression models demonstrated that steroid use, smoking, prolonged operative time, and use of absorbable mesh, acting as a surrogate marker for a more complex procedure, were significant independent predictors of wound infection. CONCLUSION: Permanent mesh placement was not associated with postoperative wound infection. Smoking was the only modifiable risk factor and preoperative smoking cessation may improve surgical outcomes in VHR.

Adult↗

PubMed2002

Increased dispersion of ventricular repolarization during head-up tilt test late after orthotopic heart transplantation in humans.

Sympathetic reinnervation after heart transplantation may be regionally heterogeneous. It remains undetermined if such heterogeneous reinnervation will result in increased ventricular repolarization dispersion. To determine the changes of ventricular repolarization after transplantation, a 15-minute, 80-degree head-up tilt test was prospectively performed with isoproterenol provocation in 30 patients who were studied within 5 months after transplantation (early group) and 30 patients who were studied > or =12 months (late group). Holter monitor was initiated to evaluate heart rate variability, which was a surrogate of cardiac reinnervation. JT dispersion was defined as the difference between maximal and minimal JT interval measurements occurring among any of the 12 leads on a standard electrocardiogram. No subject had fewer than nine measurable leads. Compared with patients in the early group, the patients in the late group had higher low frequency activity, indicating partial sympathetic reinnervation. Analysis of the electrocardiogram showed that there were significant differences in the corrected JT dispersion in the late group compared with the early group and controls (74+/-18 vs 56+/-15 and 55+/-14 ms, both P <0.05) during isoproterenol infusion. Head-up tilt test is a useful tool to unmask the increased dispersion of ventricular repolarization, particularly during states of isoproterenol infusion. Early after cardiac transplantation, neither postural changes nor isoproterenol infusion caused a significant increase of corrected JT dispersion. Late after transplantation, heterogeneous sympathetic reinnervation may result in increased corrected JT dispersion. However, whether increased dispersion of ventricular repolarization is related to cardiac death late after operation warrants further investigation in a large and long-term trial.

Adult↗

PubMed2006

Pharmacokinetics of oncolytic measles virotherapy: eventual equilibrium between virus and tumor in an ovarian cancer xenograft model.

Because of their ability to replicate, the dose-response relationships of oncolytic viruses cannot easily be predicted. To better understand the pharmacokinetics of virotherapy in relation to viral dose and schedule, we administered MV-CEA intraperitoneally in an orthotopic mouse model of ovarian cancer. MV-CEA is an attenuated oncolytic measles virus engineered to express soluble human carcinoembryonic antigen (CEA), and the virus is currently undergoing phase I clinical testing in patients with ovarian cancer. Plasma CEA levels correlate with numbers of virus-infected tumor cells at a given time, and were used as a surrogate to monitor the profiles of viral gene expression over time. The antineoplastic activity of single- or multiple-dose MV-CEA was apparent over a wide range of virus doses (10(3)-10(8) TCID(50)), with little reduction in observed antitumor efficacy, even at the lowest tested dose. However, analysis of CEA profiles of treated mice was highly informative, illustrating the variability in virus kinetics at different dose levels. The highest doses of virus were associated with higher initial levels of tumor cell killing, but the final outcome of MV-CEA therapy at all dose levels was a partial equilibrium between virus and tumor, resulting in significant slowing of tumor growth and enhanced survival of the mice.

Animals↗

PubMed2005

Statistical analysis of antigen receptor spectratype data.

MOTIVATION: The effectiveness of vertebrate adaptive immunity depends crucially on the establishment and maintenance of extreme diversity in the antigen receptor repertoire. Spectratype analysis is a method used in clinical and basic immunological settings in which antigen receptor length diversity is assessed as a surrogate for functional diversity. The purpose of this paper is to describe the systematic derivation and application of statistical methods for the analysis of spectratype data. RESULTS: The basic probability model used for spectratype analysis is the multinomial model with n, the total number of counts, indeterminate. We derive the appropriate statistics and statistical procedures for testing hypotheses regarding differences in antigen receptor distributions and variable repertoire diversity in different treatment groups. We then apply these methods to spectratype data obtained from several healthy donors to examine the differences between normal CD4+ and CD8+ T cell repertoires, and to data from a thymus transplant patient to examine the development of repertoire diversity following the transplant.

Algorithms↗

PubMed1993

Prostate-specific antigen as a measure of disease outcome in metastatic hormone-refractory prostate cancer.

PURPOSE: To evaluate the prognostic significance of pretreatment parameters and posttherapy declines in prostate-specific antigen (PSA) in relation to the survival of patients with hormone-refractory prostate cancer. PATIENTS AND METHODS: One hundred ten assessable patients treated on seven sequential protocols at Memorial Sloan-Kettering Cancer Center (MSKCC) for hormone-refractory prostate cancer were evaluated for 29 different pretherapy and posttherapy parameters, including a posttherapy decline in PSA of 50% and 80% from baseline. RESULTS: In the univariate analysis, initial Karnofsky performance status (KPS) > or = 80% was associated with a favorable outcome (P = .005), while age, extent of disease on bone scan, and individual sites of metastatic disease were not significant. No difference in survival was observed between patients with measurable or assessable (bone only) disease. Initial hemoglobin (HGB; P = .0012), alkaline phosphatase (ALK; P = .0015), and lactate dehydrogenase (LDH; P = .0002) levels were significant discriminators, while the initial PSA was not. Using a landmark analysis, a significantly longer median survival rate was observed for patients with a > or = 50% decline in PSA (median not reached) versus patients with a less than 50% decline in PSA (median, 8.6 months; P = .0001). Multivariate analysis using the Cox proportional hazards model showed that a > or = 50% decline in PSA (P = .0004) and the natural log of LDH (P = .0001) were the two most significant variables predicting survival. The model was confirmed on an independent data set from the Norwegian Radium Hospital (NRH) in Oslo, Norway. CONCLUSION: The results suggest that posttherapy PSA declines can be used as a surrogate end point to evaluate new agents in hormone-refractory prostate cancer. The criteria for response need prospective validation in phase III trials.

Aged↗

PubMed2000

Association of patients' perception of health status and exercise electrocardiogram, myocardial perfusion imaging, and ventricular function measures.

BACKGROUND: Patients' viewpoint of their health status is increasingly used as an important outcome measure of the success of treatments. Because clinicians rarely formally measure patients' health-related quality of life, the question arises whether noninvasive testing for ischemia can provide similar information regarding physical functioning and general health perception. METHODS: We measured physical functioning and general health status with the Medical Outcomes Study Short Form (SF-36) survey in 195 consecutive patients (68% male, mean age 55.6 +/- 11.1 years) referred for exercise testing with myocardial perfusion imaging. The survey was completed immediately before the exercise test. RESULTS: In the multivariate analysis, the strongest predictor of physical functioning and general health perception was metabolic equivalents. However, the best model, including demographic, clinical, and test variables, predicted only 14% of the variation in physical functioning and 10% of the variability in general health perception. CONCLUSIONS: The variation in physical functioning and general health perception, as measured by the SF-36, among patients referred for exercise testing is not predicted well by the results of the test. As expected, several test results are significantly associated with physical functioning and general health perception; however, there was substantial overlap among individual patients, suggesting that the parameters are poor surrogates for the actual assessment of the domains. If these domains are deemed important to tracking patient outcomes, then they should supplement the current assessments of these patients.

Adult↗

PubMed2002

Dissociation between hemodynamic changes and symptom improvement in patients with advanced congestive heart failure.

BACKGROUND: Changes in hemodynamic measures often serve as surrogate end points in efficacy trials for advanced heart failure, although there are few objective data to support this practice. AIMS: We compared changes in hemodynamic variables vs. changes in symptoms of decompensated heart failure in patients enrolled in a randomized trial. METHODS: We studied 201 patients with New York Heart Association (NYHA) class IIIb or IV heart failure and ejection fraction < or = 25% for > or = 3 months. Patients underwent continuous monitoring by pulmonary-artery catheter during inpatient drug administration. We assessed the relations of changes in hemodynamic variables (baseline minus final measure) to changes at 2 weeks in congestive heart failure symptoms, NYHA class, Yale Dyspnea-Fatigue Index (YDFI) score, and distance achieved in a 6-min walk. RESULTS: No hemodynamic measure significantly predicted either symptom score or NYHA classification. Mean pulmonary artery pressure and pulmonary capillary wedge pressure did show some relation to change in YDFI score in univariable, but not multivariable, analysis. No hemodynamic measure correlated significantly with changes in distance achieved in the 6-min walk test. CONCLUSION: We noted no significant association between improved hemodynamics and improved symptoms in patients with advanced heart failure. Other measures may need to be evaluated as surrogate end points in future trials.

Aged↗

PubMed2004

New developments in medical clinical trials.

This paper reviews several new developments and long-standing good practices for conducting clinical trials. Discussion starts with the need for clear statements of study objectives, proceeds to clarify target and sample population, and elaborates on primary vs. secondary variables with the need for alpha adjustment in the presence of multiple outcomes. Here we also review the issue of surrogate endpoints. Study design issues--including blinding, randomization, and multicenter studies--come next. Then we discuss the current trend of the replacement of placebo-controlled trials by active controlled non-inferiority trials, the increasing use of Independent Data Monitoring Committees, the prominence of analysis on Intention-to-Treat samples, and the importance of imputation of missing data. We close with a brief discussion of the unit of analysis, the role of newer statistical analysis methods, safety issues, subset analysis, and, most importantly, clinical significance.

Clinical Trials Data Monitoring Committees↗

PubMed2004

HRCT lung abnormalities are not a surrogate for exercise limitation in bronchiectasis.

In paediatric bronchiectasis, there has been limited work on the relationship between disease severity as assessed by exercise limitation and high resolution computed tomography (HRCT). An observational study was performed on 36 children who completed a questionnaire, physical examination, spirometry and sputum analysis, followed by a low dose of radiation protocol chest computed tomography (CT) scan and cycle ergometry incremental exercise test. A modified Bhalla score was used to score the HRCT abnormalities. The exercise variables used to assess functional status were heart rate, oxygen consumption, oxygen saturations and time of exercise. The results were compared with established normal paediatric values. The median (range) age of the children was 13 yrs (10.6-17.1). Age, sex, height, weight or pubertal status were equally distributed between the children with cystic fibrosis (CF) or non-CF bronchiectasis. The children with non-CF bronchiectasis had a lower median forced expiratory volume in one second % predicted than the children with CF (69% versus 76%, respectively). The distribution of lung disease differed between the two groups. The children with CF bronchiectasis had predominantly right upper lobe disease, and scored higher for the presence and extent of bronchiectasis. Otherwise, there was no statistical difference in the overall CT score or the individual CT parameters between the groups. There was evidence of exercise limitation in both CF and non-CF bronchiectasis compared to normal children. No consistent relationships were identified between the lung function parameters, HRCT findings or exercise parameters in either disease group. In this study, high resolution computed tomography features were not found to be markers of exercise capacity. As spirometry, high resolution computed tomography features and exercise testing give different information in children with cystic fibrosis and non-cystic fibrosis bronchiectasis, the current authors suggest all three may be required for the comprehensive assessment of respiratory status.

Adolescent↗

PubMed2007

Surrogate estimates of insulin sensitivity in subjects with hypertension.

The purpose of the study is to compare surrogate estimates of insulin sensitivity with a directly measured insulin sensitivity index, steady-state plasma glucose (SSPG) from insulin suppression test (IST), in subjects with hypertension. Two hundred and twenty-eight hypertensive patients who received IST for SSPG were included for analysis. Estimates from fasting measurements alone, homeostasis model assessment for insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI)), and indices from fasting and/or 2 h samples (ISI(0,120) and ISI(TX)) were calculated. In addition to Pearson and partial correlations, variance-component models were used to test the relationship between surrogate estimates of insulin sensitivity and SSPG. A large proportion of variance owing to covariates in the variance-component models indicated the goodness of model fit, irrespective of the independence among variables. SSPG was positively correlated with logarithmic transformation (Log) (HOMA-IR) and negatively correlated with QUICKI, Log (ISI(0,120)) and ISI(TX) (all P<0.0001). Log (ISI(0,120)) seemed to have a better correlation with SSPG (r=-0.72) than other measures in partial correlation. The proportion of variance owing to all covariates of Log (ISI(0,120)) and ISI(TX) were larger than those of Log (HOMA-IR) and QUICKI in the variance-component models. After adjustments for demographic and obesity covariates, the proportion of variance explained by Log (ISI(0,120)) were largest among the surrogate measures in the variance-component models. Our results showed that ISI(0,120) and ISI(TX) correlated better with SSPG than those used fasting measures alone (HOMA-IR and QUICKI). Log (ISI(0,120)) currently showing the strongest association with SSPG than other estimates is adaptable for use in large studies of hypertension.

Adult↗

PubMed2004

Comparative evaluation of simple indices of insulin resistance.

Various surrogate methods for the quantification of insulin sensitivity have been proposed. A comparative evaluation is lacking and is relevant for the standardization of investigative methods and comparability of results. The aims of the study were to perform a comparative validation of fasting insulin, homeostasis model assessment (HOMA), Quantitative Insulin Sensitivity Check Index (QUICKI), and revised-QUICKI (R-QUICKI) against minimal model derived estimates of insulin sensitivity (SI(MM)) in nondiabetic people and to carry out a comparative evaluation of the ability of these indices as means for the identification of individuals with the metabolic syndrome (MS) on a population basis. We used 2 data sets defined as "validation sample" and "prevalence sample". Validation sample: a total of 162 healthy men and women aged 30 to 65 years were studied by frequently sampled intravenous glucose tolerance test (FSIVGTT). SI(MM) was calculated with the Minmod program. Prevalence sample: a total of 2,731 nondiabetic men and women aged 35 to 65 years were studied. In both samples, anthropometry, blood pressure, fasting glucose, insulin, triglycerides, high-density lipoprotein (HDL) cholesterol, and free fatty acid (FFA) were measured. HOMA, QUICKI, and R-QUICKI were calculated. The MS was defined according to the Adult Treatment Panel III. Validation sample: insulin, HOMA, QUICKI, and R-QUICKI significantly correlated with SI(MM) (r = -0,53, -0.52, 0.41, 0.33; all P < .001). The finding was confirmed in obese (body mass index [BMI] > or =25 kg/m(2)), but in the normal weight, the correlation coefficient for QUICKI was significantly smaller than for the other indices. Receiver operator characteristic (ROC) curve analysis performed with SI(MM) below or above the lowest 25th percentile (ie, insulin resistance yes, no) as the outcome variable and each of the 4 indices as the test variable showed no significant differences in the areas under the curve. Prevalence sample: prevalence of the MS progressively increased across quartiles of insulin resistance as evaluated by any of the 4 indices, with no significant differences between them. The novel indices QUICKI and R-QUICKI do not perform better than HOMA and fasting insulin as surrogate measures of insulin resistance or means for the identification of people with MS in the general population.

Adult↗