A dynamic analysis of disability and labour force participation in Ireland 1995-2000

This paper aims to analyse the effect of disability on participation in the labour force, using the Irish component of the European Community Household Panel Survey 1995-2000. A range of panel models are considered, but to allow for any unobserved influences or state dependence in labour force participation, our preferred model is a dynamic panel model. We show how the estimates of current disability are changed once we control for the effect of past disability and previous participation. We compare base estimates of disability with those controlling for unobserved heterogeneity and past participation. The results suggest that the base effect of disability is overestimated by between 40-60% for men and by 5-10% for women.     

Not of one mind: mental models of clinical practice guidelines in the Veterans Health Administration

OBJECTIVE: The purpose of this paper is to present differences in mental models of clinical practice guidelines (CPGs) among 15 Veterans Health Administration (VHA) facilities throughout the United States. DATA SOURCES: Two hundred and forty-four employees from 15 different VHA facilities across four service networks around the country were invited to participate. Participants were selected from different levels throughout each service setting from primary care personnel to facility leadership. STUDY DESIGN: This qualitative study used purposive sampling, a semistructured interview process for data collection, and grounded theory techniques for analysis. DATA COLLECTION: A semistructured interview was used to collect information on participants' mental models of CPGs, as well as implementation strategies and barriers in their facility. FINDINGS: Analysis of these interviews using grounded theory techniques indicated that there was wide variability in employees' mental models of CPGs. Findings also indicated that high-performing facilities exhibited both (a) a clear, focused shared mental model of guidelines and (b) a tendency to use performance feedback as a learning opportunity, thus suggesting that a shared mental model is a necessary but not sufficient step toward successful guideline implementation. CONCLUSIONS: We conclude that a clear shared mental model of guidelines, in combination with a learning orientation toward feedback are important components for successful guideline implementation and improved quality of care.     

Mathematical Modeling and Pharmaceutical Pricing: Analyses Used to Inform In-Licensing and Developmental Go/No-Go Decisions

In the face of significant real healthcare cost inflation, pressured budgets, and ongoing launches of myriad technology of uncertain value, payers have formalized new valuation techniques that represent a barrier to entry for drugs. Cost-effectiveness analysis predominates among these methods, which involves differencing a new technological interventions marginal costs and benefits with a comparators, and comparing the resulting ratio to a payers willingness-to-pay threshold. In this paper we describe how firms are able to model the feasible range of future product prices when making in-licensing and developmental Go/No-Go decisions by considering payers use of the cost-effectiveness method. We illustrate this analytic method with a simple deterministic example and then incorporate stochastic assumptions using both analytic and simulation methods. Using this strategic approach, firms may reduce product development and in-licensing risk.The FDA in the United States or the EMEA in Europe. Coverage and reimbursement decision making for new technology entering European markets occurs at the country-level     

Addiction and its brain science

AIMS: To illustrate how modern neurobiological approaches will help to identify the neurocircuits and genes involved in addictive behavior. BACKGROUND: The current disorder concept of addiction includes neurobiological foundations and neurobiological research assuming irreversible molecular and structural changes within the brain dopamine reinforcement system, constituting the 'molecular and structural switch' from controlled drug intake to compulsive drug abuse. However, those irreversible changes have not so far been identified and it is suggested that in addition to the mesolimbic dopamine system, other brain systems including the mesocortical and nigrostriatal pathways as well as their non-dopaminergic feedback-loops might be involved in addictive behavior. NEUROBIOLOGICAL APPROACH: A three-step neurobiological approach is described that allows in a first step via novel animal models and imaging techniques to identify the neuroanatomical sites mediating voluntary drug intake, reinstatement of drug-seeking behavior, relapse, loss of control and drug intake despite negative consequences. In a subsequent step, forward genetic approaches including quantitative trait loci (QTL)-analysis and gene expression profiling are helpful in identifying so-called candidate genes. In a final step, conditional animal mutants and selective pharmacological tools are used to functionally validate candidate genes. Following this validation process, the transfer to the human situation has to be made and candidate genes have to be verified further in well-phenotyped cohorts of addicted patients. CONCLUSION: This three-step neurobiological approach, that must involve an interdisciplinary team including experimental psychologists, geneticists, molecular biologists and finally clinical addiction researchers, will allow us to understand where and how the addicted brain goes awry.     

Those Who Think They Look Worst Respond Best: Self-observer Discrepancy Predicts Response to Video Feedback Following a Speech Task

Recent evidence suggests that video feedback helps improve the accuracy of self-ratings of performance in speech-anxious participants (e.g., Rapee & Hayman, 1996. Behaviour Research and Therapy, 34, 315–322.). Evidence also suggests that this effect is stronger for participants who have a more negatively distorted impression of their performance (self-observer discrepancy; Rodebaugh & Chambless, 2002. Cognitive Therapy and Research, 26, 629–644.). Data collected in Rapee and Hayman’s study were analyzed to determine if similar results would be found in this independent sample. Evidence was found for moderating effects of self-observer discrepancy comparable to those shown in Rodebaugh and Chambless. The self-observer discrepancy itself showed relatively weak relationships with general indices of social anxiety, but a very strong relationship with initial self-rating of performance. The results suggest that self-observer discrepancy is a predictor of response to video feedback, and that clinicians may be able to estimate the discrepancy by examining self-rating in conjunction with behavior.     

The problem of analysing the relationship between change and initial value in oral health research

The relationship between initial disease status and subsequent change following treatment has attracted great interest in dental research. However, medical statisticians have repeatedly warned against correlating/regressing change with baseline because of two methodological concerns known as mathematical coupling and regression to the mean. In general, mathematical coupling occurs when one variable directly or indirectly contains the whole or part of another, and the two variables are then analyzed by using correlation or regression. Consequently, the statistical procedure of testing the null hypothesis - that the coefficient of correlation or the slope of regression is zero - may become inappropriate. Regression to the mean occurs with any variable that fluctuates within an individual or a population, either owing to measurement error and/or to physiological variation. The aim of this article was to clarify the conceptual confusion around mathematical coupling and regression to the mean within the statistical literature, and to correct a popular misconception about the correct analysis of the relationship between change and initial value. As examples that use inappropriate methods to analyze the relationship between change and baseline are still found in leading dental journals, this article seeks to help oral health researchers understand these problems and explain how to overcome them.     

Survival after spinal cord injury in Australia

OBJECTIVE: To assess survival after spinal cord injury (SCI) in Australia. DESIGN: Cohort study of incident cases from 1986 to 1997, with follow-up to the end of 1998. SETTING: Cases registered by 6 Australian treatment centers for the acute care and rehabilitation of SCI patients. PARTICIPANTS: Subjects (N=2892), age 15 years and older, from a national population-based SCI register. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Cumulative and relative survival proportions and hazard ratios. RESULTS: The all-cases cumulative survival proportion was 94% at 1 year and 86% at 10 years; the relative survival proportions were 95% and 92%, respectively. Significant predictors of survival were: age at injury, sex, neurologic level, and extent of lesion. Cox regression modeling revealed a statistically significant reduction in the 2-month (36% reduction, P=.01) and 1-year (27% reduction, P=.04) hazard ratio from 1986 to 1991 to 1992 to 1997. Benchmarking analysis revealed no statistically significant difference in survival experience between the 6 spinal treatment units. CONCLUSIONS: Further improvement in survival rates can be achieved through better understanding of the predictors, temporal patterns, and causes of death, and by benchmarking. Early deaths have an important impact on overall survival rates, and warrant further study. International standardization of methods is strongly recommended.     

A comparison of two hospitalist models with traditional care in a community teaching hospital

PURPOSE: Many studies have documented significant length of stay reduction and cost savings when hospitalist care is compared with traditional care. However, less is known about the concurrent performance of more than one hospitalist model in a single site. SUBJECTS AND METHODS: This retrospective cohort study of 10595 patients was conducted between July 2001 and June 2002 in a tertiary care community-based teaching hospital. Risk-adjusted length of stay, variable costs, 30-day readmission rates, and in-hospital and 30-day mortality were measured for patients treated by Community Physicians, Private Hospitalists and Academic Hospitalists. RESULTS: There was a 20% reduction in length of stay on the Academic Hospitalist service (p <.0001) and 8% on the Private Hospitalist service (P = .049) compared with Community Physicians. Similarly, total costs were 10% less on the Academic (P <.0001) and 6% less on the Private Hospitalist (P = .02) services compared with Community Physicians. The length of stay of Academic Hospitalists was 13% shorter than that of Private Hospitalists (P = .002); differences in costs between hospitalist groups were not statistically significant. Differences in in-hospital and 30-day mortality and 30-day readmission rates among the 3 physician groups were also not statistically significant. CONCLUSIONS: The impact on patient outcomes and resource utilization may vary with the hospitalist model used. Future studies should examine the specific organizational characteristics of hospitalists that contribute to improved patient care and resource utilization.     

Validation of ECG indices of ventricular repolarization heterogeneity: a computer simulation study

INTRODUCTION: Repolarization heterogeneity (RH) is functionally linked to dispersion in refractoriness and to arrhythmogenicity. In the current study, we validate several proposed electrocardiogram (ECG) indices for RH: T-wave amplitude, -area, -complexity, and -symmetry ratio, QT dispersion, and the Tapex-end interval (the latter being an index of transmural dispersion of the repolarization (TDR)). METHODS AND RESULTS: We used ECGSIM, a mathematical simulation model of ECG genesis in a human thorax, and varied global RH by increasing the standard deviation (SD) of the repolarization instants from 20 (default) to 70 msec in steps of 10 msec. T-wave amplitude, -area, -symmetry, and Tapex-end depended linearly on SD. T-wave amplitude increased from 275 +/- 173 to 881 +/- 456 muV, T-wave area from 34 x 10(3)+/- 21 x 10(3) to 141 x 10(3)+/- 58 x 10(3)muV msec, T-wave symmetry decreased from 1.55 +/- 0.11 to 1.06 +/- 0.23, and Tapex-end increased from 84 +/- 17 to 171 +/- 52 msec. T-wave complexity increased initially but saturated at SD = 50 msec. QT dispersion increased modestly until SD = 40 msec and more rapidly for higher values of SD. TDR increased linearly with SD. Tapex-end increased linearly with TDR, but overestimated it. CONCLUSION: T-wave complexity did not discriminate between differences in larger RH values. QT dispersion had low sensitivity in the transitional zone between normal and abnormal RH. In conclusion, T-wave amplitude, -area, -symmetry, and, with some limitations, Tapex-end and T-wave complexity reliably reflect changes in RH.     

An Optimal control approach to marketing-production planning

The problem of finding an optimal advertising and production policy in a firm is analysed using a recently proposed model of a marketing-production system. First, it is shown that the optimal control problem underlying the proposed model is a partially singular control problem. Then, a reverse-time parametric solution procedure is designed to determine the optimal advertising and production policy for the proposed model. Finally, it is shown that the results derived from the new model are applicable to problems of capacity expansion in a firm.