Stepwise item selection procedures for Rasch scales using quasi-loglinear models

Two iterative procedures for constructing Rasch scales are presented. A log-likelihood ratio test based on a quasi-loglinear formulation of the Rasch model is given by which one item at a time can be deleted from or added to an initial item set. In the so-called "top-down" algorithm, items are stepwise deleted from a relatively large initial item set, whereas in the "bottom-up" algorithm items are stepwise added to a relatively small initial item set. Both algorithms are evaluated through a simulation study with generated data. Item parameters are given for four generated unidimensional data sets and two generated two-dimensional sets. Abilities were randomly sampled from a multivariate normal distribution with a sample size of 1,000. Results for the top-down algorithm were poor, but results for the bottom-up algorithm were more encouraging. It is suggested that alternating the bottom-up algorithm with one or two iterations of the top-down algorithm would allow the procedure to reject items that were added incorrectly in a previous step

Empirical comparison between factor analysis and item response models

Many multidimensional item response theory (IRT) models have been proposed. A comparison is made between the so-called full information models and the models that use only pairwise information. Three multidimensional models described are: (1) the compensatory model of R. D. Bock and M. Aitken (1981) using the computer program TESTFACT; (2) a model based on R. P. McDonald's (1985) harmonic analysis using the program NOHARM; and (3) the computer program MAXLOG of R. L. McKinley and M. D. Reckase (1983). Five factor analysis procedures for dichotomous items are discussed. A simulation study was conducted to compare the various methods. The item parameters of four different sets of items were used with numbers of subjects set at 250, 500, and 1,000. Ten replications were generated for each set of item parameters and each sample size. All models were compared with respect to estimates of IRT and factor analysis parameters using six criteria in terms of mean squared differences between the known and estimated item parameters. The most striking result of the simulation study was that common factor analysis programs outperformed the more complex programs TESTFACT, MAXLOG, and NOHARM. It was apparent that a common factor analysis in the matrix of tetrachoric correlations yielded the best estimates. A procedure based on the mean squared residuals of the correlation matrix was also presented for assessing the dimensionality of the model. Nine tables present the data from the simulation study

Least-squares approximation of an improper by a proper correlation matrix using a semi-infinite convex program

An algorithm is presented for the best least-squares fitting correlation matrix approximating a given missing value or improper correlation matrix. The proposed algorithm is based on a solution for C. I. Mosier's oblique Procrustes rotation problem offered by J. M. F. ten Berge and K. Nevels (1977). It is shown that the minimization problem belongs to a certain class of convex programs in optimization theory. A necessary and sufficient condition for a solution to yield the unique global minimum of the least-squares function is derived from a theorem by A. Shapiro (1985). A computer program was implemented to yield the solution of the minimization problem with the proposed algorithm. This empirical verification of the condition indicates that the occurrence of non-optimal solutions with the proposed algorithm is very unlikely

Writing information transfers for out-of-hours palliative care : a controlled trial among GPs

Objective: The aim was to evaluate the effect of the implementation of an information handover form regarding patients receiving palliative care. Outcome was the information available for the out-of-hours GP co-operative. Design: We conducted a controlled trial. Setting: All GPs in Amsterdam, The Netherlands. Intervention: The experimental group (N=240) received an information handover form and an invitation for a one-hour training, the control group (N= 186) did not receive a handover form or training. We studied contacts with the GP co-operative concerning patients in palliative care for the presence and quality of information transferred by the patient's own GP. Main outcome measures: Proportion of contacts in which information was available and proportion of adequate information transfer. Results. Overall information was transferred by the GPs in 179 of the 772 first palliative contacts (23.2%). The number of contacts in the experimental group in which information was available increased significantly after intervention from 21% to 30%, compared to a decrease from 23% to 19% in the control group. The training had no additional effect. The content of the transferred information was adequate in 61.5%. There was no significant difference in the quality of the content between the groups. Conclusion: The introduction of a handover form resulted in a moderate increase of information transfers to the GP co-operative. However, the total percentage of contacts in which this information was present remained rather low. GP co-operatives should develop additional policies to improve information transfer. Key points: The out-of-hours period is potentially problematic for the delivery of optimal palliative care, often due to inadequate information transfer. Introduction of a handover form resulted in a moderate increase of transferred information. The percentage of palliative contacts remained low in cases where information was available. Adequate information was transferred in more than half of the cases

Pre- and post-radiotherapy MRI results as a predictive model for response in laryngeal carcinoma

The purpose was to determine if pre-radiotherapy (RT) and/or post-radiotherapy magnetic resonance (MR) imaging can predict response in patients with laryngeal carcinoma treated with RT. Pre- and post-RT MR examinations of 80 patients were retrospectively reviewed and associated with regard to local control. Pre-RT MR imaging parameters such as tumor involvement of specific laryngeal anatomic subsites including laryngeal cartilages and post-RT changes, i.e., complete resolution of the tumor or focal mass/asymmetric obliteration of laryngeal tissue and signal pattern on T2-weighted images, were evaluated. Local control was defined as absence of a recurrence at the primary site for 2 years. Local control rates based on pretreatment MR findings were 73% for low pre- RT risk-profile and 29% for high pre- RT risk-profile patients (p=0.0001). Based on posttreatment MR findings, local control rates were 100% score 1, 64% score 2, and 4% score 3 (p< 0.0001). Using post-RT T2-weighted images, significant association was found between differences in signal pattern and local control: 77% hypointense, 54% isointense and 15% hyperintense lesions (p<0.001). Differences between means of delay of post-MRI examination were significantly associated with regard to local control (p=0.003); recurrent tumors followed 5 months after RT were more easily detectable on MRI than recurrent tumors within 4 months after RT. Sensitivity, specificity, accuracy, negative and positive predictive values of post-RT score 3 were 96%, 76%, 83%, 98% and 66%. Pre- and post-RT MRI evaluation of the larynx can identify patients at high risk for developing local failure

Randomised controlled trial of integrated care to reduce disability from chronic low back pain in working and private life

Objective To evaluate the effectiveness of an integrated care programme, combining a patient directed and a workplace directed intervention, for patients with chronic low back pain

School functioning in 8- to 18-year-old children born after in vitro fertilization

The aim of this study was to examine the school functioning of 8- to 18-year-old children born after in vitro fertilization (IVF). We compared 233 children born after IVF to 233 matched control children born spontaneously from parents with fertility problems on measures of education level, general cognitive ability, school performance (need for extra help, repeating a grade, special education), and rates of learning and developmental disorders. No differences were found between IVF and control children on these measures of school functioning. More than 60% of adolescents at secondary school attended high academic levels (with access to high school or university). We conclude that children and adolescents born after IVF show good academic achievement and general cognitive ability. They do not experience any more educational limitations than the naturally conceived children and adolescents of the control group. The tendency of reassuring school functioning already found in younger IVF children has been shown to continue at secondary school age

Caregivers' understanding of dementia predicts patients' comfort at death: a prospective observational study

Background: Patients with dementia frequently do not receive adequate palliative care which may relate to poor understanding of the natural course of dementia. We hypothesized that understanding that dementia is a progressive and terminal disease is fundamental to a focus on comfort in dementia, and examined how family and professional caregivers' understanding of the nature of the disease was associated with patients' comfort during the dying process. Methods: We enrolled 372 nursing home patients from 28 facilities in The Netherlands in a prospective observational study (2007 to 2010). We studied both the families and the physicians (73) of 161 patients. Understanding referred to families' comprehension of complications, prognosis, having been counseled on these, and perception of dementia as "a disease you can die from" (5-point agreement scale) at baseline. Physicians reported on this perception, prognosis and having counseled on this. Staff-assessed comfort with the End-of-Life in Dementia - Comfort Assessment in Dying (EOLD-CAD) scale. Associations between understanding and comfort were assessed with generalized estimating equations, structural equation modeling, and mediator analyses. Results: A family's perception of dementia as "a disease you can die from" predicted higher patient comfort during the dying process (adjusted coefficient -0.8, 95% confidence interval (CI): -1.5; -0.06 point increment disagreement). Family and physician combined perceptions (-0.9, CI: -1.5; -0.2; 9-point scale) were also predictive, including in less advanced dementia. Forty-three percent of the families perceived dementia as a disease you can die from (agreed completely, partly); 94% of physicians did. The association between combined perception and higher comfort was mediated by the families' reporting of a good relationship with the patient and physicians' perception that good care was provided in the last week. Conclusions: Awareness of the terminal nature of dementia may improve patient comfort at the end of life. Educating families on the nature of dementia may be an important part of advance care planning

Cost-effectiveness of a workplace intervention for sick-listed employees with common mental disorders: design of a randomized controlled trial

Background. Considering the high costs of sick leave and the consequences of sick leave for employees, an early return-to-work of employees with mental disorders is very important. Therefore, a workplace intervention is developed based on a successful return-to-work intervention for employees with low back pain. The objective of this paper is to present the design of a randomized controlled trial evaluating the cost-effectiveness of the workplace intervention compared with usual care for sick-listed employees with common mental disorders. Methods. The study is designed as a randomized controlled trial with a follow-up of one year. Employees eligible for this study are on sick leave for 2 to 8 weeks with common mental disorders. The workplace intervention will be compared with usual care. The workplace intervention is a stepwise approach that aims to reach consensus about a return-to-work plan by active participation and strong commitment of both the sick-listed employee and the supervisor. Outcomes will be assessed at baseline, 3, 6, 9 and 12 months. The primary outcome of this study is lasting return-to-work, which will be acquired from continuous registration systems of the companies after the follow-up. Secondary outcomes are total number of days of sick leave during the follow-up, severity of common mental disorders, coping style, job content, and attitude, social influence, and self-efficacy determinants. Cost-effectiveness will be evaluated from the societal perspective. A process evaluation will also be conducted. Discussion. Return-to-work is difficult to discuss in the workplace for sick-listed employees with mental disorders and their supervisors. Therefore, this intervention offers a unique opportunity for the sick-listed employee and the supervisor to discuss barriers for return-to-work. Results of this study will possibly contribute to improvement of disability management for sick-listed employees with common mental disorders. Results will become available in 2009. Trial registration. ISRCTN92307123. © 2008 van Oostrom et al; licensee BioMed Central Ltd