A modular hybrid simulation framework for complex manufacturing system design

For complex manufacturing systems, the current hybrid Agent-Based Modelling and Discrete Event Simulation (ABM–DES) frameworks are limited to component and system levels of representation and present a degree of static complexity to study optimal resource planning. To address these limitations, a modular hybrid simulation framework for complex manufacturing system design is presented. A manufacturing system with highly regulated and manual handling processes, composed of multiple repeating modules, is considered. In this framework, the concept of modular hybrid ABM–DES technique is introduced to demonstrate a novel simulation method using a dynamic system of parallel multi-agent discrete events. In this context, to create a modular model, the stochastic finite dynamical system is extended to allow the description of discrete event states inside the agent for manufacturing repeating modules (meso level). Moreover, dynamic complexity regarding uncertain processing time and resources is considered. This framework guides the user step-by-step through the system design and modular hybrid model. A real case study in the cell and gene therapy industry is conducted to test the validity of the framework. The simulation results are compared against the data from the studied case; excellent agreement with 1.038% error margin is found in terms of the company performance. The optimal resource planning and the uncertainty of the processing time for manufacturing phases (exo level), in the presence of dynamic complexity is calculated

Predicting Time on Prolonged Benefits for Injured Workers with Acute Back Pain

Introduction Some workers with work-related compensated back pain (BP) experience a troubling course of disability. Factors associated with delayed recovery among workers with work-related compensated BP were explored. Methods This is a cohort study of workers with compensated BP in 2005 in Ontario, Canada. Follow up was 2æyears. Data was collected from employers, employees and health-care providers by the Workplace Safety and Insurance Board (WSIB). Exclusion criteria were: (1) no-lost-time claims, (2) \u3e30ædays between injury and claim filing, (3) 65æyears. Using proportional hazard models, we examined the prognostic value of information collected in the first 4æweeks after injury. Outcome measures were time on benefits during the first episode and time until recurrence after the first episode. Results Of 6,657 workers, 1,442 were still on full benefits after 4æweeks. Our final model containing age, physical demands, opioid prescription, union membership, availability of a return-to-work program, employer doubt about work-relatedness of injury, worker?s recovery expectations, participation in a rehabilitation program and communication of functional ability was able to identify prolonged claims to a fair degree [area under the curve (AUC)æ=æ.79, 95æ% confidence interval (CI) .74?.84]. A model containing age, sex, physical demands, opioid prescription and communication of functional ability was less successful at predicting time until recurrence (AUCæ=æ.61, 95æ% CI .57, .65). Conclusions Factors contained in information currently collected by the WSIB during the first 4æweeks on benefits can predict prolonged claims, but not recurrent claims. Electronic supplementary material The online version of this article (doi:10.1007/s10926-014-9534-5) contains supplementary material, which is available to authorized users

Multidisciplinary outpatient care program for patients with chronic low back pain: design of a randomized controlled trial and cost-effectiveness study [ISRCTN28478651]

<p>Abstract</p> <p>Background</p> <p>Chronic low back pain (LBP) is a major public and occupational health problem, which is associated with very high costs. Although medical costs for chronic LBP are high, most costs are related to productivity losses due to sick leave. In general, the prognosis for return to work (RTW) is good but a minority of patients will be absent long-term from work. Research shows that work related problems are associated with an increase in seeking medical care and sick leave. Usual medical care of patients is however, not specifically aimed at RTW.</p> <p>The objective is to present the design of a randomized controlled trial, i.e. the BRIDGE-study, evaluating the effectiveness in improving RTW and cost-effectiveness of a multidisciplinary outpatient care program situated in both primary and outpatient care setting compared with usual clinical medical care for patients with chronic LBP.</p> <p>Methods/Design</p> <p>The design is a randomized controlled trial with an economic evaluation alongside. The study population consists of patients with chronic LBP who are completely or partially sick listed and visit an outpatient clinic of one of the participating hospitals in Amsterdam (the Netherlands). Two interventions will be compared. 1. a multidisciplinary outpatient care program consisting of a workplace intervention based on participatory ergonomics, and a graded activity program using cognitive behavioural principles. 2. usual care provided by the medical specialist, the occupational physician, the patient's general practitioner and allied health professionals. The primary outcome measure is sick leave duration until full RTW. Sick leave duration is measured monthly by self-report during one year. Data on sick leave during one-year follow-up are also requested form the employers. Secondary outcome measures are pain intensity, functional status, pain coping, patient satisfaction and quality of life. Outcome measures are assessed before randomization and 3, 6, and 12 months later. All statistical analysis will be performed according to the intension-to-treat principle.</p> <p>Discussion</p> <p>Usual care of primary and outpatient health services isn't directly aimed at RTW, therefor it is desirable to look for care which is aimed at RTW. Research shows that several occupational interventions in primary care are aimed at RTW. They have shown a significant reduction of sick leave for employee with LBP. If a comparable reduction of sick leave duration of patients with chronic LBP of who attend an outpatient clinic can be achieved, such reductions will be obviously substantial for the Netherlands and will have a considerable impact.</p> <p>Trial registration</p> <p>ISRCTN28478651</p

“It’s hard to tell”. The challenges of scoring patients on standardised outcome measures by multidisciplinary teams: a case study of Neurorehabilitation

Background Interest is increasing in the application of standardised outcome measures in clinical practice. Measures designed for use in research may not be sufficiently precise to be used in monitoring individual patients. However, little is known about how clinicians and in particular, multidisciplinary teams, score patients using these measures. This paper explores the challenges faced by multidisciplinary teams in allocating scores on standardised outcome measures in clinical practice. Methods Qualitative case study of an inpatient neurorehabilitation team who routinely collected standardised outcome measures on their patients. Data were collected using non participant observation, fieldnotes and tape recordings of 16 multidisciplinary team meetings during which the measures were recited and scored. Eleven clinicians from a range of different professions were also interviewed. Data were analysed used grounded theory techniques. Results We identified a number of instances where scoring the patient was 'problematic'. In 'problematic' scoring, the scores were uncertain and subject to revision and adjustment. They sometimes required negotiation to agree on a shared understanding of concepts to be measured and the guidelines for scoring. Several factors gave rise to this problematic scoring. Team members' knowledge about patients' problems changed over time so that initial scores had to be revised or dismissed, creating an impression of deterioration when none had occurred. Patients had complex problems which could not easily be distinguished from each other and patients themselves varied in their ability to perform tasks over time and across different settings. Team members from different professions worked with patients in different ways and had different perspectives on patients' problems. This was particularly an issue in the scoring of concepts such as anxiety, depression, orientation, social integration and cognitive problems. Conclusion From a psychometric perspective these problems would raise questions about the validity, reliability and responsiveness of the scores. However, from a clinical perspective, such characteristics are an inherent part of clinical judgement and reasoning. It is important to highlight the challenges faced by multidisciplinary teams in scoring patients on standardised outcome measures but it would be unwarranted to conclude that such challenges imply that these measures should not be used in clinical practice for decision making about individual patients. However, our findings do raise some concerns about the use of such measures for performance management

A Prospective Study of Return to Work Across Health Conditions: Perceived Work Attitude, Self-efficacy and Perceived Social Support

Background The aim of the present study was to conduct subgroup-analyses in a prospective cohort of workers on long-term sickness absence to investigate whether associations between perceived work attitude, self-efficacy and perceived social support and time to RTW differ across different health conditions. Methods The study was based on a sample of 926 workers on sickness absence (6–12 weeks). The participants filled out a baseline questionnaire and were subsequently followed until the tenth month after listing sick. Perceived work attitude was measured with a Dutch language version of the Work Involvement Scale. Perceived social support was measured with a self-constructed standardized scale reflecting a person’s perception of social support regarding RTW. Self-efficacy was measured with the standardised Dutch version of the General self-efficacy scale, assessing the subjects’ expectations of their general capacities. The sample was divided into three subgroups: musculoskeletal health conditions, other physical health conditions and mental health conditions. Anova analyses and Cox proportional hazards regression analyses were used to identify differences in association between the three factors and the time to RTW between different subgroups. Results The associations between the perceived work attitude, self-efficacy and perceived social support and the time to RTW vary across different health condition subgroups, not only with regard to the strength of the association but also for the type of factor. In the multivariate model, hazard ratios (HRs) of 1.33 (95% CI 1.01–1.75) in the musculoskeletal subgroup, and 1.26 (95% CI 0.89–1.78) in the other physical subgroup were found in perceived work attitude. With regard to perceived social support HRs of 1.39 (95% CI 1.12–1.99) respectively 1.51 (1.05–2.17) in the same subgroups were found. Only self-efficacy remained in the multivariate model in all subgroups with HRs of 1.49 (95% CI 1.12–1.99) in the musculoskeletal subgroup, 1.53 (95% CI 1.07–2.18) in the other physical subgroup and 1.60 (1.07–2.40) in the mental subgroup. Conclusions The results of this study show that perceived work attitude, self-efficacy and perceived social support are relevant predictors with regard to the time to RTW in all types of health conditions, but that important differences are observed in type of factor and strengths of the relationships between physical and mental health conditions

An intervention program with the aim to improve and maintain work productivity for workers with rheumatoid arthritis: design of a randomized controlled trial and cost-effectiveness study

<p>Abstract</p> <p>Background</p> <p>Workers with rheumatoid arthritis (RA) often experience restrictions in functioning at work and participation in employment. Strategies to maintain work productivity exist, but these interventions do not involve the actual workplace. Therefore the aim of this study is to investigate the (cost)effectiveness of an intervention program at the workplace on work productivity for workers with RA.</p> <p>Methods/design</p> <p>This study is a randomized controlled trial (RCT) in specialized rheumatology treatment centers in or near Amsterdam, the Netherlands. Randomisation to either the control or the intervention group is performed at patient level. Both groups will receive care as usual by the rheumatologist, and patients in the intervention group will also take part in the intervention program. The intervention program consists of two components; integrated care, including a participatory workplace intervention. Integrated care involves a clinical occupational physician, who will act as care manager, to coordinate the care. The care manager has an intermediate role between clinical and occupational care. The participatory workplace intervention will be guided by an occupational therapist, and involves problem solving by the patient and the patients’ supervisor. The aim of the workplace intervention is to achieve consensus between patient and supervisor concerning feasible solutions for the obstacles for functioning at work. Data collection will take place at baseline and after 6 and 12 months by means of a questionnaire. The primary outcome measure is work productivity, measured by hours lost from work due to presenteeism. Secondary outcome measures include sick leave, quality of life, pain and fatigue. Cost-effectiveness of the intervention program will be evaluated from the societal perspective.</p> <p>Discussion</p> <p>Usual care of primary and outpatient health services is not aimed at improving work productivity. Therefore it is desirable to develop interventions aimed at improving functioning at work. If the intervention program will be (cost)effective, substantial improvements in work productivity might be obtained among workers with RA at lower costs. Results are expected in 2015.</p> <p>Trial registration number</p> <p>NTR2886</p