Missing item responses in latent growth analysis: Item response theory versus classical test theory

In medical research, repeated questionnaire data is often used to measure and model latent variables across time. Through a novel imputation method, a direct comparison is made between latent growth analysis under classical test theory and item response theory, while also including effects of missing item responses. For classical test theory and...

Long-term Sickness Absence in a Working Population: Development and Validation of a Risk Prediction Model in a Large Dutch Prospective Cohort

Background: Societal expenditures on work-disability benefits is high in most Western countries. As a precursor of long-term work restrictions, long-term sickness absence (LTSA) is under continuous attention of policy makers. Different healthcare professionals can play a role in identification of persons at risk of LTSA but are not well trained....

Development of Prediction Models for Sick Leave Due to Musculoskeletal Disorders

Purpose The aim of this study was to develop prediction models to determine the risk of sick leave due to musculoskeletal disorders (MSD) in non-sick listed employees and to compare models for short-term (i.e., 3 months) and long-term (i.e., 12 months) predictions. Methods Cohort study including 49,158 Dutch employees who participated in...

Comparison of logistic-regression based methods for simple mediation analysis with a dichotomous outcome variable

BACKGROUND: Logistic regression is often used for mediation analysis with a dichotomous outcome. However, previous studies showed that the indirect effect and proportion mediated are often affected by a change of scales in logistic regression models. To circumvent this, standardization has been proposed. The aim of this study was to show the...

Passive imputation and parcel summaries are both valid to handle missing items in studies with many multi-item scales

Previous studies showed that missing data in multi-item scales can best be handled by multiple imputation of item scores. However, when many scales are used, the number of items will become too large for the imputation model to reliably estimate imputations. A solution is to use passive imputation or a parcel summary score that combine and...

Analysing outcome variables with floor effects due to censoring: A simulation study with longitudinal trial data

Background: Randomised controlled trials (RCTs) are the gold standard to estimate treatment effects. When patients receive effective treatment over time they may reach the limit of a certain measurement scale. This phenomenon is known as censoring and leads to skewed distributions of the outcome variable with an excess of either low (floor...

Methods for significance testing of categorical covariates in logistic regression models after multiple imputation: power and applicability analysis

Background. Multiple imputation is a recommended method to handle missing data. For significance testing after multiple imputation, Rubin’s Rules (RR) are easily applied to pool parameter estimates. In a logistic regression model, to consider whether a categorical covariate with more than two levels significantly contributes to the model,...

Effectiveness of phone and e-mail lifestyle counseling for long term weight control among overweight employees

OBJECTIVES: To determine the effectiveness of a weight-management program with personal counseling by phone or e-mail. METHODS: A randomized controlled trial of a 6-month program comparing two modes of intervention delivery (phone, n = 462; Internet, n = 464) with self-directed materials (control, n = 460), among overweight employees. Change in...

The cost-effectiveness of a lifestyle physical activity intervention in addition to a work style intervention on recovery from neck and upper limb symptoms and pain reduction in computer workers

Objectives: To evaluate the cost-effectiveness of a work style (WS) intervention and a work style plus physical activity (WSPA) intervention in computer workers with neck and upper limb symptoms compared with usual care. Methods: An economic evaluation was conducted from an employer's perspective and alongside a randomised controlled trial in...

The prognosis of chronic low back pain is determined by changes in pain and disability in the initial period

Background context: The recovery of patients with chronic low back pain (LBP) is slow. Furthermore, it is recently proposed that chronic LBP needs a prognostic approach to determine who will develop clinically significant back pain. Therefore, it is imperative to identify prognostic factors that are mostly seen in chronic LBP patients at an...

Potential savings of a program to prevent ankle sprain recurrence: Economic evaluation of a randomized controlled trial

Background: The most common ankle injury is the lateral ankle sprain. Dutch annual sports-related ankle sprain costs can roughly be estimated at 187,200,000. Research has shown that proprioceptive training accounts for an approximated overall 50% reduction in ankle sprain recurrence rate. Hypothesis: An unsupervised proprioceptive training...

Return to work in a cohort of low back pain patients: Development and validation of a clinical prediction rule

Background From the viewpoint of cost prevention, it is necessary to identify patients that are of high risk for long-term work disability, production loss and sick-leave. Methods Secondary data analysis in a cohort of 628 workers on sick-leave between 3 and 6 weeks due to low back pain (LBP). The association of a broad set of demographic, work,...

Variable selection under multiple imputation using the bootstrap in a prognostic study

Background. Missing data is a challenging problem in many prognostic studies. Multiple imputation (MI) accounts for imputation uncertainty that allows for adequate statistical testing. We developed and tested a methodology combining MI with bootstrapping techniques for studying prognostic variable selection. Method. In our prospective cohort...

Workers' beliefs and expectations affect return to work over 12 months

Background: Successful management of workers on sick leave due to low back pain depends on the identification by the occupational physician of modifiable prognostic factors in the early phase of sick-leave. The prognostic value of factors which influence the course of low back pain and return to work in occupational health care is unclear....

The effectiveness of high-intensity versus low-intensity back schools in an occupational setting: A pragmatic randomized controlled trial

Study Design. Randomized controlled trial. Objectives. To compare high- and low-intensity back schools with usual care in occupational health care. Summary of Background Data. The content and intensity of back schools vary widely and the methodologic quality of randomized controlled trials is generally weak. Until now, no back school has proven...

Prognostic factors for duration of sick leave in patients sick listed with acute low back pain: A systematic review of the literature

Background: The percentages of patients with acute low back pain (LBP) that go on to a chronic state varies between studies from 2% to 34%. In some of these cases low back pain leads to great costs. Aims: To evaluate the evidence for prognostic factors for return to work among workers sick listed with acute LBP. Methods: Systematic literature...

Back schools in occupational health care: Design of a randomized controlled trial and cost-effectiveness study

To describe the design of a randomized controlled trial (RCT), including a cost-effectiveness analysis, comparing high-intensity and low-intensity back schools with usual care in occupational health care. RCT and cost-effectiveness analysis. Employees sick-listed for a period of 3 to 6 weeks because of nonspecific low back pain. High-intensity...

Terugkeer naar het werk in een cohort van werknemers met lage rugpijn: Ontwikkeling en validatie van een klinische predictieregel