Yaling Yang

A review of studies mapping (or cross walking) non-preference based measures of health to generic preference-based measures

Clinical studies use a wide variety of health status measures to measure health related quality of life, many of which cannot be used in cost-effectiveness analysis using cost per quality adjusted life year (QALY). Mapping is one solution that is gaining popularity as it enables health state utility values to be predicted for use in cost per QALY analysis when no preference-based measure has been included in the study. This paper presents a systematic review of current practice in mapping between non-preference based measures and generic preference-based measures, addressing feasibility and validity, circumstances under which it should be considered and lessons for future mapping studies. This review found 30 studies reporting 119 different models. Performance of the mappings functions in terms of goodness-of-fit and prediction was variable and unable to be generalised across instruments. Where generic measures are not regarded as appropriate for a condition, mapping does not solve this problem. Most testing in the literature occurs at the individual level yet the main purpose of these functions is to predict mean values for subgroups of patients, hence more testing is required.

Localization of Deformations Within the Amygdala in Individuals With Psychopathy

CONTEXT Despite the repeated findings of impaired fear conditioning and affective recognition in psychopathic individuals, there has been a paucity of brain imaging research on the amygdala and no evidence suggesting which regions within the amygdala may be structurally compromised in individuals with psychopathy. OBJECTIVE To detect global and regional anatomical abnormalities in the amygdala in individuals with psychopathy. DESIGN Cross-sectional design using structural magnetic resonance imaging. SETTING Participants were recruited from high-risk communities (temporary employment agencies) in the Los Angeles, California, area and underwent imaging at a hospital research facility at the University of Southern California. PARTICIPANTS Twenty-seven psychopathic individuals as defined by the Hare Psychopathy Checklist-Revised and 32 normal controls matched on age, sex, and ethnicity. MAIN OUTCOME MEASURES Amygdala volumes were examined using traditional volumetric analyses and surface-based mesh modeling methods were used to localize regional surface deformations. RESULTS Individuals with psychopathy showed significant bilateral volume reductions in the amygdala compared with controls (left, 17.1%; right, 18.9%). Surface deformations were localized in regions in the approximate vicinity of the basolateral, lateral, cortical, and central nuclei of the amygdala. Significant correlations were found between reduced amygdala volumes and increased total and facet psychopathy scores, with correlations strongest for the affective and interpersonal facets of psychopathy. CONCLUSIONS Results provide the first evidence, to our knowledge, of focal amygdala abnormalities in psychopathic individuals and corroborate findings from previous lesion studies. Findings support prior hypotheses of amygdala deficits in individuals with psychopathy and indicate that amygdala abnormalities contribute to emotional and behavioral symptoms of psychopathy.

Abnormal temporal and prefrontal cortical gray matter thinning in psychopaths

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Sex differences in orbitofrontal gray as a partial explanation for sex differences in antisocial personality

Attention is increasingly being given to understanding sex difference in psychopathology to better understand the etiology of disorders. This study tests the hypothesis that sex differences in ventral and middle frontal gray volume contribute to sex differences in antisocial personality disorder (APD) and crime. Participants were recruited from temporary employment agencies, consisting of normal controls, substance/alcohol-dependent controls, axis I/II psychiatric controls and individuals with APD. An independent sample of female volunteers was also recruited. Magnetic resonance imaging volumes of superior frontal, middle frontal, inferior frontal, orbital frontal and rectal gyral frontal gray matter, and dimensional scores of APD and criminal behavior were assessed. APD males when compared with male controls showed an 8.7% reduction in orbitofrontal gray volume, a 17.3% reduction in middle frontal gray and a 16.1% reduction in right rectal gray. Reduced middle and orbitofrontal volumes were significantly associated with increased APD symptoms and criminal offending in both males and females. Males as a whole had reduced orbitofrontal and middle frontal gray volume when compared with females, and controlling for these brain differences reduced the gender difference in the antisocial personality/behavior by 77.3%. Findings were not a function of psychiatric comorbidity, psychosocial risk factors, head injury or trauma exposure. Findings implicate structural differences in the ventral and middle frontal gray as both a risk factor for APD and as a partial explanation for sex differences in APD.

Neurodevelopmental marker for limbic maldevelopment in antisocial personality disorder and psychopathy

BACKGROUND Antisocial personality disorder and psychopathy have been hypothesised to have a neurodevelopmental basis, but this proposition has not been formally tested. AIMS This study tests the hypothesis that individuals with cavum septum pellucidum (CSP), a marker of limbic neural maldevelopment, will show higher levels of psychopathy and antisocial personality. METHOD Cavum septum pellucidum was assessed using anatomical magnetic resonance imaging in a community sample. Those with CSP (n = 19) were compared with those lacking CSP (n = 68) on antisocial personality, psychopathy and criminal offending. RESULTS Those with CSP had significantly higher levels of antisocial personality, psychopathy, arrests and convictions compared with controls. The pervasiveness of this association was indicated by the fact that those lacking a diagnosis of antisocial personality disorder, but who were charged or convicted for an offence, had a more extensive CSP than non-antisocial controls. Results could not be attributed to prior trauma exposure, head injury, demographic factors or comorbid psychiatric conditions. CONCLUSIONS Our findings appear to be the first to provide evidence for a neurodevelopmental brain abnormality in those with antisocial personality disorder and psychopathy, and support the hypothesis that early maldevelopment of limbic and septal structures predisposes to the spectrum of antisocial behaviours.

Estimating a Preference-Based Index for a 5-Dimensional Health State Classification for Asthma Derived from the Asthma Quality of Life Questionnaire

Background: This article presents a valuation study to estimate a preference-based index for a 5-dimensional health state classification for asthma (AQL-5D) derived from the Asthma Quality of Life Questionnaire (AQLQ). Methods: A sample of 307 members of the UK general population valued 99 asthma health states selected from the AQL-5D using the time tradeoff technique. Models were estimated to predict all possible 3125 health states defined by the AQL-5D, and the models were compared in terms of their ability to predict mean values for the 99 states. Results: Mean health state values ranged from 0.39 to 0.94 based on an average of 22 valuations per state. A main effects model estimated on mean health state values and adjusted for consistency had the best predictive ability (mean absolute error of 0.047 and only 9/98 states with errors >0.1) and the most logical consistency with levels of the AQL-5D. The low number of valuations per state may have resulted in unreliable estimates for the models. Preference-based condition specific measures are limited in their ability to make cross-disease comparisons. Conclusion: This is the first study to derive a condition-specific preference-based measure from an existing measure of health-related quality of life in asthma for use in economic evaluation.

The first stage of developing preference-based measures: constructing a health-state classification using Rasch analysis.

ObjectiveTo set out the methodological process for using Rasch analysis alongside classical psychometric methods in the development of a health-state classification that is amenable to valuation.MethodsThe overactive bladder questionnaire is used to illustrate a five step process for deriving a reduced health-state classification from an existing non-preference-based health-related quality-of-life instrument. Step I uses factor analysis to establish instrument dimensions, step II excludes items that do not meet the initial validation process and step III uses criteria based on Rasch analysis and other psychometric testing to select the final items for the health-state classification. In step IV, item levels are examined and Rasch analysis is used to explore the possibility of reducing the number of item levels. Step V repeats steps I–IV on alternative data sets in order to validate the selection of items for the health-state classification.ResultsThe techniques described enable the construction of a five-dimension health-state classification, the OAB-5D, amenable to valuation tasks that will allow the derivation of preference weights.ConclusionsThe health-related quality of life of patients with conditions like overactive bladder can be valued and quality adjustment weights estimated for calculation of quality-adjusted life years.

The Use of Rasch Analysis in Reducing a Large Condition-Specific Instrument for Preference Valuation The Case of Moving from AQLQ to AQL-5D

The majority of health-related quality-of-life instruments are not preference-based measures and so cannot be used within cost utility analysis. The Asthma Quality of Life Questionnaire (AQLQ) is one such instrument. The aim of this study was to develop a health state classification that was amenable to valuation from the AQLQ, this being the 1st stage in developing a condition-specific preference-based measure for asthma patients. Rasch models were applied to samples of responders to the AQLQ with the aim of selecting a number of items for a preference-based utility measure (AQL-5D). Selection of items for the evaluation survey was supported with classical psychometric criteria for item selection (feasibility, internal consistency, floor and ceiling effects, and responsiveness). Rasch analysis proved to be a useful tool in assisting in the initial process of selecting items from an existing health-related quality-of-life instrument in the construction of the AQL-5D. The method is recommended for use alongside classical psychometric testing to aid in the development of preference-based measures.

Determination of estrogens in human urine by high-performance liquid chromatography/diode array detection with ultrasound-assisted cloud-point extraction.

A novel and efficient analytical methodology is proposed for extracting and preconcentrating three kinds of estrogens (17β-estradiol (βE2), estrone (E1), and diethylstilbestrol (DES)) in human urine prior to high-performance liquid chromatography (HPLC) analysis. It is based on the induction of micellar organized medium by using a nonionic surfactant (Tergitol TMN-6) to extract the target estrogens. Ultrasound was applied to enhance the extraction efficiency. Parameters affecting the extraction of target analytes including the concentration of surfactant, temperature, extraction time, sample pH, ionic strength, and centrifuging time were investigated. Under the optimum conditions, the linear range of βE2, E1, and DES was from 5.0 to 1000 ng/ml. All correlation coefficients of the calibration curves were higher than 0.997. The relative standard deviations (RSD, n=5) were 2.36-5.27% and the limits of detection (LOD) were 0.1, 0.2, and 0.1 ng/ml for βE2, E1, and DES in human urine, respectively. The results indicated that the method was successfully applied for analyzing βE2, E1, and DES in human urine.

Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid–liquid ultrasonic extraction

An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al(3+)) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N)=3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.